💥💥💥 What is k-epsilon model in Ansys Fluent and what is used for ?

 The k-epsilon model is a type of turbulence model that is used in computational fluid dynamics (CFD) simulations. It is based on two transport equations for the turbulence kinetic energy (k) and its dissipation rate (epsilon). The k-epsilon model can capture the effects of mean velocity gradients, buoyancy, compressibility, and heat and mass transfer on the turbulent flow. It is one of the most widely used turbulence models in engineering applications because of its robustness, economy, and reasonable accuracy for a wide range of flows¹².

Ansys Fluent is a software package that allows users to perform CFD simulations using various turbulence models, including the k-epsilon model. Ansys Fluent provides three variants of the k-epsilon model: the standard, the RNG, and the realizable k-epsilon models. Each variant has different methods of calculating the turbulent viscosity, the turbulent Prandtl numbers, and the generation and destruction terms in the epsilon equation³. The k-epsilon model in Ansys Fluent can be used for modeling internal and external flows, separated flows, jets, flows with high-pressure gradients, and flows through curved geometries⁴⁵.

Source:

(1) ANSYS FLUENT 12.0 User's Guide - 33.3.3 Viscous Model Dialog Box - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node1022.htm.

(2) 12.4.1 Standard k Model Overview - University of Washington. https://courses.washington.edu/mengr544/handouts-10/Fluent-k-epsilon.pdf.

(3) ANSYS FLUENT 12.0 User's Guide - 12.4 Steps in Using a Turbulence Model. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node411.htm.

(4) Difference between K-epsilon and K-omega Turbulence Model - Ansys .... https://forum.ansys.com/forums/topic/difference-between-k-epsilon-and-k-omega-turbulence-model/.

(5) k-epsilon and Laminar differrence - Ansys Learning Forum. https://forum.ansys.com/forums/topic/k-epsilon-and-laminar-differrence/.

What are the limitations of k-epsilon model?

The k-epsilon model is a popular and widely used turbulence model, but it also has some limitations that affect its accuracy and applicability. Some of the limitations are:

- It assumes that the turbulence is isotropic, which means that the ratio between Reynolds stress and mean rate of deformation is the same in all directions. This is not true for flows with strong anisotropy, such as swirling, rotating, or curved flows²³.

- It requires a high Reynolds number, which means that the inertial forces are much larger than the viscous forces. This is not true for flows near the wall, where the viscous effects are important. Therefore, the k-epsilon model needs a near-wall treatment, such as wall functions or low-Reynolds number corrections, to account for the wall effects¹².

- It does not capture the effects of history and rapid distortion on the turbulence. This means that the model cannot handle flows with large adverse pressure gradients, boundary layer separation, or shock waves. Therefore, the k-epsilon model may under-predict the extent of recirculation zones or over-predict the turbulent kinetic energy at stagnation points¹⁴⁵.

These limitations can be overcome by using more advanced turbulence models, such as Reynolds stress models, large eddy simulation, or detached eddy simulation, which can account for the effects of anisotropy, compressibility, history, and distortion on the turbulence. However, these models are also more complex, computationally expensive, and sensitive to initial and boundary conditions. Therefore, the choice of the turbulence model depends on the trade-off between accuracy and efficiency for a given flow problem.

Source: 

(1) The k-ε Turbulence Model - COMSOL Multiphysics. https://doc.comsol.com/5.5/doc/com.comsol.help.cfd/cfd_ug_fluidflow_single.06.088.html.

(2) OpenFOAM: User Guide: k-epsilon. https://www.openfoam.com/documentation/guides/latest/doc/guide-turbulence-ras-k-epsilon.html.

(3) K-epsilon turbulence model - Wikipedia. https://en.wikipedia.org/wiki/K-epsilon_turbulence_model.

(4) Validation and analysis of turbulence modeling in pipe elbow under .... https://link.springer.com/article/10.1007/s40430-022-03899-9.

(5) Limitations and empirical extensions of the k-epsilon model as applied .... https://ntrs.nasa.gov/search.jsp?R=19840035309.

Is k-epsilon model good for low quality meshes ?

The k-epsilon model is not very suitable for low quality meshes, especially near the wall regions. This is because the k-epsilon model requires a high Reynolds number, which means that the inertial forces are much larger than the viscous forces. This is not true for flows near the wall, where the viscous effects are important. Therefore, the k-epsilon model needs a near-wall treatment, such as wall functions or low-Reynolds number corrections, to account for the wall effects¹². However, these treatments are sensitive to the mesh quality and resolution, and may not work well for coarse or skewed meshes³⁴.

A better alternative for low quality meshes is the k-omega model, which is more robust and accurate for near-wall flows. The k-omega model does not require a high Reynolds number, and can handle flows with large adverse pressure gradients, boundary layer separation, or shock waves. The k-omega model is also good in resolving internal flows, separated flows and jets and flows with high-pressure gradient and also internal flows through curved geometries³. However, the k-omega model may be more computationally expensive and sensitive to initial and boundary conditions than the k-epsilon model². Therefore, the choice of the turbulence model depends on the trade-off between accuracy and efficiency for a given flow problem.

Source: 

(1) K-epsilon Turbulence Model | Global Settings | SimScale. https://www.simscale.com/docs/simulation-setup/global-settings/k-epsilon/.

(2) K-epsilon turbulence model - Wikipedia. https://en.wikipedia.org/wiki/K-epsilon_turbulence_model.

(3) Difference between K-epsilon and K-omega Turbulence Model. https://forum.ansys.com/forums/topic/difference-between-k-epsilon-and-k-omega-turbulence-model/.

(4) k-epsilon model: which criteria do I have to meet for the near wall mesh?. https://forum.ansys.com/forums/topic/k-epsilon-model-which-criteria-do-i-have-to-meet-for-the-near-wall-mesh/.

What is the difference between k-epsilon and k-omega models?

The k-epsilon and k-omega models are both types of turbulence models that are used in computational fluid dynamics (CFD) simulations. They are based on two transport equations for the turbulence kinetic energy (k) and either its dissipation rate (epsilon) or its specific dissipation rate (omega). The main difference between them is that the k-epsilon model is more suitable for flow away from the wall, while the k-omega model is more accurate for near-wall flow regions¹².

The k-epsilon model assumes that the turbulence is isotropic, which means that the ratio between Reynolds stress and mean rate of deformation is the same in all directions. This is not true for flows with strong anisotropy, such as swirling, rotating, or curved flows. The k-epsilon model also requires a high Reynolds number, which means that the inertial forces are much larger than the viscous forces. This is not true for flows near the wall, where the viscous effects are important. Therefore, the k-epsilon model needs a near-wall treatment, such as wall functions or low-Reynolds number corrections, to account for the wall effects. However, these treatments are sensitive to the mesh quality and resolution, and may not work well for coarse or skewed meshes¹².

The k-omega model does not assume isotropy, and can handle flows with large adverse pressure gradients, boundary layer separation, or shock waves. The k-omega model does not require a high Reynolds number, and can resolve the viscous layer without wall functions. The k-omega model is also good in resolving internal flows, separated flows, jets, flows with high-pressure gradients, and flows through curved geometries¹³. However, the k-omega model may be more computationally expensive and sensitive to initial and boundary conditions than the k-epsilon model².

A common variant of the k-omega model is the SST (shear stress transport) model, which blends the k-epsilon and k-omega models to achieve the best of both worlds. The SST model uses the k-omega formulation in the near-wall region and switches to the k-epsilon formulation in the free-stream region. The SST model can capture the effects of mean velocity gradients, buoyancy, compressibility, and heat and mass transfer on the turbulent flow. The SST model is one of the most widely used turbulence models in engineering applications because of its robustness, economy, and reasonable accuracy for a wide range of flows¹⁴.

Source: 

(1) Which Turbulence Model Should I Choose for My CFD Application?. https://www.comsol.com/blogs/which-turbulence-model-should-choose-cfd-application/.

(2) Use of k-epsilon and k-omega Models - CFD Online. https://www.cfd-online.com/Forums/main/75554-use-k-epsilon-k-omega-models.html.

(3) Difference between K-epsilon and K-omega Turbulence Model. https://forum.ansys.com/forums/topic/difference-between-k-epsilon-and-k-omega-turbulence-model/.

(4) What is the difference between k-epsilon and k-omega model .... https://rampfest-hudson.com/what-is-the-difference-between-k-epsilon-and-k-omega-model/.

(5) What is the difference between k-epsilon and K-Omega?. https://vidque.com/what-is-the-difference-between-k-epsilon-and-k-omega/.

🎅 🎅 🎅 The story of Santa Claus who, with a hangover on New Year's Eve, had to test Ansys Mechanical a bit

 Santa Claus had a wild night on New Year's Eve. He drank too much eggnog, danced with the elves, and sang karaoke with Rudolph. He woke up the next morning with a hangover and a terrible headache. He groaned and reached for his phone, hoping to check his messages and go back to sleep.

But he was in for a rude awakening. He had received an urgent email from Ansys, the company that provided him with the software for designing his sleigh and toys. They wanted him to test their new product, Ansys Mechanical, a finite element analysis (FEA) software for structural engineering. They said it was a great opportunity for him to improve his designs and optimize his performance.

Santa Claus was not in the mood for this. He hated learning new software, especially when he had a headache. He wished he could just stick to his old methods, but he knew he had to keep up with the times. He decided to give it a try, hoping it would be easy and intuitive.

He downloaded Ansys Mechanical and opened it on his laptop. He was greeted by a user interface that looked complicated and confusing. He saw a lot of buttons, menus, and icons, but he had no idea what they did. He looked for a tutorial or a help guide, but he couldn't find any. He felt frustrated and overwhelmed.

He decided to start with something simple. He wanted to model a toy car and see how it would behave under different loads and conditions. He imported a CAD model of the car and tried to mesh it. He clicked on the mesh button and waited for the results. He expected to see a nice and smooth mesh, but he was shocked by what he saw. The mesh was coarse and distorted, with a lot of poor elements and gaps. He didn't know what went wrong or how to fix it.

He tried to adjust the mesh settings, but he only made it worse. He tried to apply boundary conditions and loads, but he got a lot of errors and warnings. He tried to run the analysis, but he got a message saying that the solution was not converged. He tried to view the results, but he got a blank screen. He tried to use the post-processing tools, but he didn't understand what they meant.

He spent hours trying to figure out how to use Ansys Mechanical, but he only got more frustrated and angry. He felt like he was wasting his time and energy. He cursed and slammed his laptop shut. He decided to give up on Ansys Mechanical and go back to his old software. He thought it was too complicated and difficult for him. He wondered why Ansys wanted him to use it in the first place.

He didn't realize that Ansys Mechanical was actually a powerful and versatile tool that could help him solve complex structural engineering problems and make better, faster design decisions. He didn't know that it had a dynamic and integrated platform that could connect with other physics for even greater fidelity. He didn't know that it had a persistent, dependable, and accurate solver technology that could handle linear and nonlinear, static and dynamic, and thermal and acoustic analyses. He didn't know that it had a lot of features and capabilities that could help him with advanced materials modeling, vibration, coupled field, explicit, acoustics, crack and fracture, structural optimization, fatigue life, and more.

He also didn't know that Ansys Mechanical had a lot of resources and events that could help him learn and use it effectively. He didn't know that he could access online courses, webinars, blogs, forums, and support communities that could provide him with guidance and tips. He didn't know that he could find a lot of tutorials, examples, and documentation that could show him how to use the software step by step. He didn't know that he could contact Ansys experts and engineers who could answer his questions and solve his problems.

Santa Claus missed a great opportunity to improve his skills and designs with Ansys Mechanical. He could have learned a lot and had a lot of fun with it. He could have made his sleigh and toys more efficient, reliable, and safe. He could have delivered more joy and happiness to the children of the world.

But he didn't. He chose to stay in his comfort zone and ignore the new possibilities. He was too stubborn and lazy to try something new. He was too proud and arrogant to ask for help. He was too drunk and hungover to think clearly.

He regretted his decision later, when he realized what he had missed. He wished he had given Ansys Mechanical a chance. He wished he had been more open-minded and curious. He wished he had been more smart and brave.

But it was too late. He had lost his chance. He had lost his edge. He had lost his magic.

The end.

💥💥💥HAPPY AND HEALTHY NEW YEAR !!!💥💥💥

🎅 🎅 🎅 What are the main differences between Ansys Fluent and CFX ?

Ansys Fluent and CFX are both powerful computational fluid dynamics (CFD) solvers, but they have some differences in their features, capabilities, and applications. Here are some of the main differences between them:

- Fluent uses a cell-centered approach while CFX uses a vertex-centered approach. This means that Fluent can handle more complex mesh topologies, such as polyhedral and cutcell meshes, while CFX is limited to tetrahedral and hexahedral meshes¹².

- Fluent has post-processing capabilities of its own while CFX needs a dedicated post-processor, such as CFD-Post¹². Fluent also has more options for mesh adaption and simulation acceleration with a GPU².

- CFX has a built-in expression language (CEL) that allows users to define algebraic equations and monitor them during the run¹². Fluent requires user-defined functions (UDFs) for customization, which can be more challenging for beginners¹.

- CFX is more suitable for turbomachinery applications, as it has specialized features for rotating machinery, such as frozen rotor and transient blade row models²³. Fluent is more preferred for high Mach number flows, such as supersonic and hypersonic flows².

Source: 

(1) What are the differences between CFX and Fluent? - Ansys Learning Forum. https://forum.ansys.com/forums/topic/what-are-the-differences-between-cfx-and-fluent/.

(2) Compare Ansys CFX vs. Ansys Fluent | G2. https://www.g2.com/compare/ansys-cfx-vs-ansys-fluent.

(3) Reply To: What are the differences between CFX and Fluent?. https://forum.ansys.com/forums/reply/58903/.

(4) What are the differences between CFX and Fluent? - Ansys Learning Forum. https://forum.ansys.com/forums/topic/what-are-the-differences-between-cfx-and-fluent/.

(5) Compare Ansys CFX vs. Ansys Fluent | G2. https://www.g2.com/compare/ansys-cfx-vs-ansys-fluent.

(6) Reply To: What are the differences between CFX and Fluent?. https://forum.ansys.com/forums/reply/58903/.

(7) Getty Images. https://www.gettyimages.com/detail/news-photo/in-this-photo-illustration-the-ansys-logo-seen-displayed-on-news-photo/1212478964. 

Which one is more popular in industry?

That's a good question, but it's not easy to answer. The popularity of Ansys Fluent and CFX may depend on the industry, the region, the application, and the preference of the users. According to some sources, Fluent is more widely used than CFX in general, especially in the aerospace, automotive, and chemical industries¹². However, CFX has a strong presence in the power generation and turbomachinery sectors¹³. Ultimately, both solvers have their strengths and weaknesses, and the best choice may depend on the specific problem and the user's experience.

Source: 

(1) What are the differences between CFX and Fluent? - Ansys Learning Forum. https://forum.ansys.com/forums/topic/what-are-the-differences-between-cfx-and-fluent/.

(2) Ansys CFX or Ansys Fluent : r/CFD - Reddit. https://www.reddit.com/r/CFD/comments/yp3vf0/ansys_cfx_or_ansys_fluent/.

(3) Compare Ansys CFX vs. Ansys Fluent | G2. https://www.g2.com/compare/ansys-cfx-vs-ansys-fluent.

Which one  is more accurate on Conjugate Heat Transfer analysis? Ansys Fluent or CFX?

Conjugate heat transfer (CHT) analysis is a type of simulation that models the heat transfer within and between fluids and solids¹. The accuracy of CHT analysis depends on many factors, such as the mesh quality, the boundary conditions, the solver settings, and the physical models²³. Therefore, it is not possible to say which solver, Ansys Fluent or CFX, is more accurate in general, as the results may vary depending on the specific problem and the user's expertise.

However, some studies have compared the performance of Fluent and CFX for different CHT applications, such as liquid-cooled IGBT assemblies⁴, heat exchangers⁵, and turbomachinery. These studies have shown that both solvers can produce similar results, but they may have different advantages and disadvantages in terms of computational efficiency, convergence behavior, and ease of use. For example, Fluent may have more options for mesh adaption and acceleration with a GPU², while CFX may have more features for rotating machinery and expression language³.

Therefore, the best way to determine which solver is more accurate for your CHT analysis is to try both of them and compare the results with experimental data or analytical solutions, if available. You can also consult the Ansys documentation and forums for more guidance and tips on how to use Fluent and CFX for CHT analysis. 😊

Source:

(1) How does the "Loosely Coupled Conjugate Heat Transfer" function work .... https://forum.ansys.com/forums/topic/how-does-the-loosely-coupled-conjugate-heat-transfer-function-work/.

(2) THERMAL ANALYSIS/CONJUGATE HEAT TRANSFER ANALYSIS IN ANSYS CFX THERMAL .... https://www.youtube.com/watch?v=Jx39uFHtHbs.

(3) CHT analysis using Fluent Solver | Ansys Courses. https://courses.ansys.com/index.php/courses/conjugate-heat-transfer/lessons/cht-analysis-of-liquid-cooled-igbt-assembly/topic/part-3-using-fluent-solver/.

(4) CHT Analysis in Ansys Discovery | Ansys Courses. https://courses.ansys.com/index.php/courses/conjugate-heat-transfer/.

(5) Ansys Fluent Heat Transfer Modeling | Ansys Training. https://www.ansys.com/training-center/course-catalog/fluids/ansys-fluent-heat-transfer-modeling.

(6) CHT Analysis in Ansys Discovery | Ansys Courses. https://courses.ansys.com/index.php/courses/conjugate-heat-transfer/.

(7) Ansys Fluent Heat Transfer Modeling | Ansys Training. https://www.ansys.com/training-center/course-catalog/fluids/ansys-fluent-heat-transfer-modeling.

(8) CHT analysis using Fluent Solver | Ansys Courses. https://courses.ansys.com/index.php/courses/conjugate-heat-transfer/lessons/cht-analysis-of-liquid-cooled-igbt-assembly/topic/part-3-using-fluent-solver/.

(9) CHT analysis using Fluent Solver | Ansys Courses. https://courses.ansys.com/index.php/courses/conjugate-heat-transfer/lessons/cht-analysis-of-liquid-cooled-igbt-assembly/topic/part-3-using-fluent-solver/.

What is the difference between Fluent and Star-CCM+?

Fluent and Star-CCM+ are both commercial computational fluid dynamics (CFD) software packages developed by Ansys and Siemens, respectively. They have some similarities and differences in their features, capabilities, and applications. Here are some of the main differences between them:

- Fluent uses a cell-centered finite volume method while Star-CCM+ uses a vertex-centered finite volume method. This means that Fluent can handle more complex mesh topologies, such as polyhedral and cutcell meshes, while Star-CCM+ is limited to tetrahedral and hexahedral meshes¹².

- Fluent has its own post-processing capabilities while Star-CCM+ requires a separate post-processor, such as CFD-Post or FieldView¹². Fluent also has more options for mesh adaption and simulation acceleration with a GPU².

- Star-CCM+ has a built-in expression language (CEL) that allows users to define algebraic equations and monitor them during the run¹². Fluent requires user-defined functions (UDFs) for customization, which can be more challenging for beginners¹.

- Star-CCM+ is more suitable for turbomachinery applications, as it has specialized features for rotating machinery, such as frozen rotor and transient blade row models²³. Fluent is more preferred for high Mach number flows, such as supersonic and hypersonic flows².

Source: 

(1) Siemens STAR CCM+ Vs. ANSYS Fluent | Resolved Analytics. https://www.resolvedanalytics.com/theflux/comparing-cfd-software-part-4-comprehensive-cfd-software-packages.

(2) Fluent vs Star CCM vs Openfoam -- CFD Online Discussion Forums. https://www.cfd-online.com/Forums/ansys/213810-fluent-vs-star-ccm-vs-openfoam.html.

(3) Compare Ansys Fluent vs. Simcenter STAR-CCM+ | G2. https://www.g2.com/compare/ansys-fluent-vs-simcenter-star-ccm.

(4) Siemens STAR CCM+ Vs. ANSYS Fluent | Resolved Analytics. https://www.resolvedanalytics.com/theflux/comparing-cfd-software-part-4-comprehensive-cfd-software-packages.

(5) Fluent vs Star CCM vs Openfoam -- CFD Online Discussion Forums. https://www.cfd-online.com/Forums/ansys/213810-fluent-vs-star-ccm-vs-openfoam.html.

(6) Comparison of STAR-CCM+ and ANSYS Fluent for Simulating Indoor Airflows. https://engineering.purdue.edu/~yanchen/paper/2018-1.pdf.

🎅 🎅 🎅 Using Ansys Fluent on Dronamics Case Study - The Black Swan

 Dronamics is a company that is developing and operating a cargo drone airline, using its flagship unmanned drone, the Black Swan¹. The Black Swan is a new type of cargo drone, remotely-piloted and fuel-efficient, suitable for a longer range and higher load factor than electric solutions². It can carry 350 kg of cargo up to 2,500 km, at an 80% lower cost than any aircraft³. It is also designed to run on biofuels and hydrogen-based fuels, making it more sustainable and eco-friendly². 

AI image od default drone (not connected to Black Swan project) 

Dronamics aims to enable same-day delivery for everyone, everywhere, by creating an air cargo ecosystem that can serve the needs of people and industries in all corners of the planet¹. Dronamics has already licensed its technology to fly in the EU, and has partnered with various airports and logistics providers to launch its service⁴⁵. Dronamics is a pioneer in the field of cargo drone aviation, and has been recognized as the "2022 and 2023 Sustainable Drone Technology Company of the Year" by Freightweek².

Source: 

(1) World's First Cargo Drone Airline | Dronamics. https://www.dronamics.com/.

(2) The Black Swan | Dronamics. https://www.dronamics.com/theblackswan.

(3) Dronamics launches drone-based cargo airline - Air Cargo News. https://www.aircargonews.net/airlines/dronamics-launches-drone-based-cargo-airline/.

(4) Dronamics to unveil first production Black Swan aircraft. https://www.aircargonews.net/airlines/drones/dronamics-to-unveil-first-production-black-swan-aircraft/.

(5) Dronamics' Black Swan Autonomous Freighter Achieves First Flight .... https://www.futureflight.aero/news-article/2023-05-29/dronamics-black-swan-cargo-drone-completes-first-flight-test.

Can you tell me more about the technology behind Black Swan?

The Black Swan is a cargo drone that is remotely-piloted and fuel-efficient. It uses a **Rotax engine** that can run on various fuels, including biofuels and hydrogen-based fuels⁶. It has a **wingspan of 16 m** and a **fuselage of 8 m**. It can carry up to **350 kg** of cargo in a **3.5 cbm** capacity. It can fly up to **2,500 km** at a **speed of 200 kmh**. It can operate from runways as short as **400 m**, unpaved¹. It has a **proprietary design** and a **world leading in-house avionics team** that built it specifically for cargo⁵. It is also **CarbonNeutral certified** and has **60% less emissions** than current transport options¹. It was named the **"2022 and 2023 Sustainable Drone Technology Company of the Year"** by Freightweek¹. The Black Swan is a revolutionary cargo drone that aims to enable same-day delivery for everyone, everywhere².

Source: 

(1) Black Swan: The first “cargo drone airline” in the world plans to take .... https://engineeringexploration.com/black-swan/.

(2) The Black Swan | Dronamics. https://www.dronamics.com/theblackswan.

(3) DRONAMICS Black Swan Cargo UAV Unveiling - Unmanned Systems Technology. https://www.unmannedsystemstechnology.com/2021/12/dronamics-black-swan-uav-unveiling/.

(4) World's First Cargo Drone Airline | Dronamics. https://www.dronamics.com/.

(5) The Black Swan | Dronamics. https://bing.com/search?q=Black+Swan+drone+technology.

(6) Meet Black Swan: The cargo drones to be used by DHL for urgent .... https://siliconcanals.com/news/dronamics-partners-with-dhl/.

How does the Black Swan drone fly?

The Black Swan drone flies like a conventional airplane, using a fixed wing and a gasoline-powered engine. It takes off and lands from runways as short as 400 m, and can fly up to 2,500 km at a speed of 200 kmh. It is remotely piloted by a human operator, who controls the drone from a mobile ground station. The drone uses a proprietary avionics system that ensures safe and reliable flight¹.

Source: 

(1) Dronamics' Black Swan Cargo Drone Completes First Flight Test. https://www.futureflight.aero/news-article/2023-05-29/dronamics-black-swan-cargo-drone-completes-first-flight-test.

(2) World's First Cargo Drone Airline | Dronamics. https://www.dronamics.com/.

(3) Black Swan: The first “cargo drone airline” in the world plans to take .... https://engineeringexploration.com/black-swan/.

(4) Black Swan: World's first 'cargo drone airline' aims to fly in early 2023. https://interestingengineering.com/innovation/worlds-first-cargo-drone-airline-2023.

What exactly was counted using Ansys Fluent in the Black Swan project?

Ansys Fluent is a software that can simulate the fluid dynamics and heat transfer of various systems. In the Black Swan project, Dronamics used Ansys Fluent to optimize the design and performance of their cargo drone. According to their case study¹, they used Ansys Fluent to:

- Simulate the airflow around the drone and optimize its shape for improved aerodynamics

- Simulate the combustion in the engine and optimize the fuel efficiency and emissions

- Simulate the structural stress and deformation of the drone and optimize the material and weight

By using Ansys Fluent, Dronamics was able to reduce the development and optimization time by approximately 60% and cut the design time by almost half¹. Ansys Fluent helped them to create a more efficient and eco-friendly cargo drone.

Source: 

(1) CASE STUDY - Ansys. https://www.ansys.com/content/dam/product/fluids/fluent/dronamics-case-study.pdf.

(2) CASE STUDY - Ansys. https://www.ansys.com/content/dam/product/fluids/fluent/dronamics-case-study.pdf.

(3) On the effect of Black Swans on projects - Medium. https://medium.com/nplan/on-the-effect-of-black-swans-on-projects-532c887bfe04.

(4) Black Swan Project - Wikipedia. https://en.wikipedia.org/wiki/Black_Swan_Project

Can you tell me more about cargo drone industry trends?

Cargo drones are unmanned aerial vehicles (UAVs) that can transport goods or products from one place to another. They can be used for various purposes, such as industrial delivery, emergency supplies, and last-mile delivery. Some of the key trends in the cargo drone industry are:

- **Rising demand for on-time and on-site delivery**: Cargo drones can offer faster, cheaper, and more convenient delivery services than conventional methods, especially in remote or hard-to-reach areas. They can also reduce traffic congestion, CO2 emissions, and carbon footprint. According to a market report, the cargo drone market is projected to grow from USD 534 million in 2022 to USD 17.9 billion by 2030, with a CAGR of 55.1% in that period¹.

- **Increasing use of cargo drones in military operations**: Cargo drones can also be used for military purposes, such as delivering supplies, weapons, or medical aid to soldiers in combat zones. They can also perform reconnaissance, surveillance, and intelligence missions. Cargo drones can enhance the operational efficiency, safety, and security of the military forces. According to a market report, the defense segment is expected to account for the largest share of the cargo drone market by 2030².

- **Innovation and development of new technologies**: Cargo drones are constantly evolving and improving, thanks to the innovation and development of new technologies, such as advanced sensors, software, propulsion systems, and communication systems. These technologies can enable cargo drones to perform more complex and diverse tasks, such as loading and offloading, autonomous navigation, obstacle avoidance, and collision detection. Some examples of innovative cargo drone technologies are the Black Swan drone by Dronamics³, the gas turbine by Turbotech⁴, and the freeze-drying system by CRB⁵.

Source: 

(1) Cargo drones: A potential gamechanger in the logistics industry. https://www.rolandberger.com/en/Insights/Publications/Cargo-drones-A-potential-gamechanger-in-the-logistics-industry.html.

(2) Cargo Drone Market Size, Industry Insights, Companies: A Comprehensive .... https://www.marketsandmarkets.com/Market-Reports/cargo-drones-market-252936360.html.

(3) Cargo Drones Market Growth Factors, Key Trends, Analysis, Outlook .... https://www.thebusinessresearchcompany.com/report/cargo-drones-global-market-report.

(4) Global cargo drone market size forecast 2030 | Statista. https://www.statista.com/statistics/1415129/worldwide-cargo-drone-market-revenue-forecast/.

(5) The use of drones in the logistics industry - Globalia Blog. https://www.globalialogisticsnetwork.com/blog/2023/05/03/global-drone-logistics-market-in-2023/.

🎅 🎅 🎅 Strange cases and memes about Ansys Fluent

 I'm glad you are interested in strange and funny cases where Ansys Fluent was used. Here are some more web search results that might amuse you:

- [Simulation Examples, Homework, and Quizzes | Ansys Courses](^1^): A course that teaches the basics of compressible flows using Ansys Fluent, with simulation examples, homework, and quizzes. Some of the examples include isentropic compression in a piston-cylinder assembly, an airfoil in different flow regimes, and constant volume heat addition and removal¹.

- [How can I compare two cases side-by-side? - CFD Online](^2^): A forum thread where users discuss how to compare two Fluent cases in CFD Post, and learn how to synchronize the views and perform operations on the results². Some of the comments are quite funny, such as "what's that", "I can't see a padlock", and "Your picture looks like CFX 13.0 not Fluent 13.0"².

- [CFD-Tyro/Ansys-Fluent-Tutorial-case - GitHub](^3^): A GitHub repository that contains Ansys Fluent tutorial cases, such as a 2D laminar pipe flow, a 3D turbulent backward-facing step, and a 3D supersonic flow over a wedge³. The repository name is a bit of a tongue twister, don't you think?

- [ANSYS FLUENT 12.0 User's Guide - 6.3.13 FLUENT 4 Case Files - ENEA](^4^): A user's guide that explains how to import FLUENT 4 case files into Ansys Fluent 12.0⁴. FLUENT 4 is a very old version of Fluent, dating back to the early 1990s. It's surprising that someone would still use it, or need to import it into a newer version.

Source:

(1) Simulation Examples, Homework, and Quizzes | Ansys Courses. https://courses.ansys.com/index.php/courses/basics-of-compressible-flows/lessons/simulation-examples-homework-and-quizzes-10/.

(2) Simulation Examples, Homework, and Quizzes | Ansys Courses. https://courses.ansys.com/index.php/courses/basics-of-compressible-flows/lessons/simulation-examples-homework-and-quizzes-10/.

(3) How can I compare two cases side-by-side? - CFD Online. https://www.cfd-online.com/Forums/fluent/97122-how-can-i-compare-two-cases-side-side.html.

(4) How can I compare two cases side-by-side? - CFD Online. https://www.cfd-online.com/Forums/fluent/97122-how-can-i-compare-two-cases-side-side.html.

(5) CFD-Tyro/Ansys-Fluent-Tutorial-case - GitHub. https://github.com/CFD-Tyro/Ansys-Fluent-Tutorial-case.

(6) CFD-Tyro/Ansys-Fluent-Tutorial-case - GitHub. https://github.com/CFD-Tyro/Ansys-Fluent-Tutorial-case.

(7) ANSYS FLUENT 12.0 User's Guide - 6.3.13 FLUENT 4 Case Files - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node181.htm.

(8) ANSYS FLUENT 12.0 User's Guide - 6.3.13 FLUENT 4 Case Files - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node181.htm.

(9) Getty Images. https://www.gettyimages.com/detail/news-photo/in-this-photo-illustration-the-ansys-logo-seen-displayed-on-news-photo/1212478964.

Funny memes on Ansys Fluent 

Sure, I can show you some funny memes about Ansys Fluent, which is a software for computational fluid dynamics. Here are some memes that I found on the web:

- [A meme](^1^) that shows a sarcastic reaction to someone who says they are fluent in Ansys Fluent¹.

- [A GIF](^2^) that shows a simulation of a car crashing into a wall, with the caption "When you forget to set the boundary conditions in Ansys Fluent"².

- [A video](^3^) that features a compilation of memes that are related to sarcasm, with the title "Fluent Sarcasm Delight: Memes That Will Have You Rolling with Laughter"³.

Source:

(1) 50 Hilarious Memes That You Might Appreciate If You Speak Fluent .... https://www.boredpanda.com/hilarious-sarcasm-only-memes/.

(2) 50 Hilarious Memes That You Might Appreciate If You Speak Fluent .... https://www.boredpanda.com/hilarious-sarcasm-only-memes/.

(3) Ansys GIFs - Get the best GIF on GIPHY. https://giphy.com/explore/ansys.

(4) Ansys GIFs - Get the best GIF on GIPHY. https://giphy.com/explore/ansys.

(5) Fluent Sarcasm Delight: Memes That Will Have You Rolling with ... - YouTube. https://www.youtube.com/watch?v=fn58DmTjuYM.

(6) Fluent Sarcasm Delight: Memes That Will Have You Rolling with ... - YouTube. https://www.youtube.com/watch?v=fn58DmTjuYM.

Story of Bob and his modelling in Ansys Fluent 

Bob was a mechanical engineering student who had to complete a project on fluid dynamics. He had heard of Ansys Fluent, a powerful software for fluid simulation, but he had never used it before. He decided to download the free student version from the Ansys website[^1^][2] and give it a try.

He installed the software on his laptop and opened it. He was greeted by a user-friendly interface that offered him various options to create and run a simulation. He clicked on the "New Project" button and chose a template for a simple pipe flow. He thought that this would be an easy way to start and learn the basics of Ansys Fluent.

He followed the instructions on the screen and entered the parameters for the pipe geometry, the fluid properties, and the boundary conditions. He then clicked on the "Mesh" button to generate a mesh for the computational domain. He was impressed by the speed and quality of the meshing process. He clicked on the "Solve" button to start the simulation.

He expected to see some results in a few minutes, but nothing happened. He checked the status bar and saw that the solver was still running. He waited for another 10 minutes, but still no results. He wondered what was wrong. He opened the solver log and saw a lot of messages that he didn't understand. He saw words like "convergence", "residuals", "iterations", and "error". He felt confused and frustrated.

He decided to search for some help on the internet. He typed "Ansys Fluent tutorial" on Bing and found a link to a webinar by Ansys[^2^][3]. He clicked on it and watched the video. He learned that Ansys Fluent had a lot of advanced physics models and capabilities that he didn't know about. He learned that he had to choose the appropriate turbulence model, set up the monitors and convergence criteria, and check the solution quality and accuracy. He realized that he had skipped a lot of important steps in his simulation setup.

He felt overwhelmed by the amount of information and complexity of Ansys Fluent. He wished he had taken a course or read a book on fluid simulation before trying to use the software. He decided to quit the software and delete the project. He thought that maybe he should try something simpler, like Excel or Matlab. He hoped that his professor would not notice his lack of skills and knowledge in fluid dynamics.

🎅 🎅 🎅 The story of Santa Claus who modeled in Ansys :) 🎅 🎅 🎅

Santa Claus was busy preparing for his annual delivery of gifts to children all over the world. He had a list of names, addresses, and preferences for each child, and he had to make sure that his sleigh and reindeer were ready for the long journey.

One of his main concerns was the aerodynamics of his sleigh. He wanted to optimize the shape and design of his sleigh to reduce drag and increase lift, so that he could travel faster and more efficiently. He also wanted to ensure that his sleigh was strong enough to withstand the high speeds and pressures of flying through the air.

To achieve this, Santa decided to use Ansys, a software for engineering simulation. He had learned how to use Ansys from one of his elves, who was an expert in computational fluid dynamics (CFD). Santa created a 3D model of his sleigh using Ansys Workbench, and then imported it into Ansys Fluent, a solver for CFD analysis.

He set up the boundary conditions, such as the air density, viscosity, and velocity, and the angle of attack of his sleigh. He also defined the material properties of his sleigh, such as the density, elasticity, and strength. He then ran the simulation, and waited for the results.

After a few minutes, Ansys Fluent displayed the results on Santa's screen. He could see the contours of pressure, velocity, and turbulence around his sleigh, as well as the forces and moments acting on his sleigh. He could also see the stress and strain distribution on his sleigh, and the deformation and displacement of his sleigh.

Santa was pleased with the results. He saw that his sleigh had a low drag coefficient, a high lift coefficient, and a high lift-to-drag ratio. He also saw that his sleigh had a low stress and strain level, and a small deformation and displacement. He concluded that his sleigh was aerodynamically efficient and structurally sound.

He thanked his elf for teaching him how to use Ansys, and praised him for his excellent work. He then loaded his sleigh with gifts, and harnessed his reindeer. He put on his red suit and hat, and checked his list one last time. He was ready to go.

He climbed onto his sleigh, and gave a loud "Ho ho ho!" He waved to his elves, and said, "Merry Christmas to all, and to all a good night!" He then whipped his reins, and his sleigh took off into the sky. He flew over the rooftops, and delivered his gifts to the children. He smiled as he heard their joy and gratitude.

He was happy that he had used Ansys to improve his sleigh. He knew that it had made his job easier and faster. He also knew that it had made his sleigh safer and more comfortable. He thought to himself, "Ansys is the best gift I ever received."

MERRY CHRISTMAS AND HAPPY NEW YEAR !!!!

💥💥💥 Which turbulence model for the rotating fan in Ansys Fluent?

There are different turbulence models available in Ansys Fluent, such as Spalart-Allmaras, k-epsilon, k-omega, SST, and GEKO. Each model has its own advantages and disadvantages, depending on the flow conditions and the accuracy required. Some factors that may influence the choice of turbulence model are:

- The Reynolds number of the flow

- The near-wall treatment

- The inlet boundary conditions

- The mesh resolution and quality

- The computational cost and time

For a rotating fan with radial inlet and outlet, you may want to consider using a sliding mesh model with a turbulent boundary layer approach. This can capture the effects of blade tip gap variation, flow recirculation inside blade passage, and other phenomena that depend on the turbulence modeling. You may also want to use a low-Re model such as k-omega or SST for better resolution of boundary layers.

One possible turbulence model that you can try is the GEKO (Generalized K-Omega) model, which offers a flexible and robust approach to RANS turbulence modeling. It has several tunable model constants that can be adjusted to match specific flow conditions. You can watch two videos that introduce this model in Ansys Fluent [here](^3^).

Another possible turbulence model that you can try is the SST-kw (Steady-State Turbulence-kw) model, which is recommended for highly accurate resolution of boundary layers. It has a wall function mesh that simplifies the computation and reduces the computational time. You can read more about this model in [this document](^4^).

Source:

(1) Introducing the GEKO Turbulence Model in Ansys Fluent. https://ansyskm.ansys.com/announcement/introducing-the-geko-turbulence-model-in-ansys-fluent/.

(2) ANSYS FLUENT 12.0 User's Guide - 12. Modeling Turbulence - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node405.htm.

(3) Modeling Turbulent Flows Introductory FLUENT Training. https://www.southampton.ac.uk/~nwb/lectures/GoodPracticeCFD/Articles/Turbulence_Notes_Fluent-v6.3.06.pdf.

(4) Fan Modelling: turbulence model -- CFD Online Discussion Forums. https://www.cfd-online.com/Forums/fluent/45907-fan-modelling-turbulence-model.html.

(5) Lecture 7: Turbulence Modeling Introduction to ANSYS Fluent - Academia.edu. https://www.academia.edu/36090206/Lecture_7_Turbulence_Modeling_Introduction_to_ANSYS_Fluent.

Which turbulence model will be the best for centrifugal fan ?

There is no definitive answer to which turbulence model is the best for a centrifugal fan, as different models may have different advantages and disadvantages depending on the flow conditions and the accuracy required. However, based on the web search results, I can provide you with some information and suggestions that may help you choose a suitable model for your simulation.

One of the factors that may influence the choice of turbulence model is the Reynolds number of the flow, which is a dimensionless parameter that characterizes the ratio of inertial forces to viscous forces in a fluid. The Reynolds number can be calculated from the density, velocity, and viscosity of the fluid, as well as from the geometry and size of the fan components. Generally, higher Reynolds numbers indicate more turbulent flows, which may require more complex models to capture the effects of turbulence.

Another factor that may influence the choice of turbulence model is the near-wall treatment, which is a method to account for the effects of boundary layer separation and recirculation near the wall. The near-wall treatment can be done by using different approaches, such as using a wall function mesh or using a modified k-epsilon model. The wall function mesh simplifies the computation by replacing some terms in the k-epsilon model with wall functions that depend on local velocity gradients. However, this approach may introduce some errors or inaccuracies in certain regions or flow regimes.

A third factor that may influence the choice of turbulence model is the inlet boundary conditions, which are given by various parameters such as inlet pressure, inlet velocity distribution function (VDF), inlet blade angle, and inlet clearance gap. These parameters affect how the flow enters and exits the fan impeller and volute. For example, an inlet VDF can determine whether there is a uniform or non-uniform flow distribution along the impeller passage. An inlet blade angle can affect how much lift or drag force is generated by each blade section. An inlet clearance gap can affect how much turbulence is generated by mixing between air and fluid.

A fourth factor that may influence the choice of turbulence model is the mesh resolution and quality, which are determined by various parameters such as grid size, grid spacing, grid type (sliding or fixed), grid refinement level (global or local), etc. The mesh resolution and quality affect how accurately and efficiently each grid element represents a physical quantity such as velocity or pressure. Higher resolution and quality grids can capture more details and features of complex flows, but they also require more computational resources and time.

A fifth factor that may influence the choice of turbulence model is also computational cost and time, which are affected by various parameters such as number of iterations per time step (NIT), time step size (GST), solver type (finite volume or finite difference), etc. Computational cost and time are important considerations when performing large-scale simulations with many fans or other components. Lower cost and time simulations can reduce operational costs and increase efficiency.

Based on these factors, you may want to consider using one or more models that have been tested and validated for similar flow conditions as your simulation case. Some examples of models that have been used for centrifugal fans are:

- The k-epsilon model (an industry standard for many years), which has two main advantages: it has simple mathematical form; it has good accuracy for low-Reynolds-number flows.

- The SST-kw (Steady-State Turbulence-kw) model (recommended for highly accurate resolution of boundary layers), which has two main advantages: it has a wall function mesh that simplifies computation; it has good accuracy for high-Reynolds-number flows.

- The GEKO (Generalized K-Omega) model (a flexible and robust approach to RANS turbulence modeling), which has several tunable model constants that can be adjusted to match specific flow conditions.

- The SST-reattachment modification (RM) model (a proposed modification to improve SST performance), which has two main advantages: it reduces local inflow in confined areas; it improves agreement with experimental data.

- The RSM-SSG (Speziale et al., Sarkar & Gatski) model (a modified k-epsilon model with improved near-wall treatment), which has two main advantages: it reduces numerical diffusion; it improves agreement with experimental data.

You can find more information about these models in [this document](^4^), [this article](^2^), [this paper](^3^), [this paper](^5^), [this paper](^6^).

Source:

(1) Tonal noise of voluteless centrifugal fan generated by turbulence .... https://pubs.aip.org/aip/pof/article/33/7/075110/1077103/Tonal-noise-of-voluteless-centrifugal-fan.

(2) A Comparative Study on Numerical Flow Simulations of a Centrifugal .... https://www.mdpi.com/1996-1073/16/23/7864/html.

(3) Assessment of Turbulence Model Predictions for an Aero-Engine .... https://asmedigitalcollection.asme.org/turbomachinery/article/133/1/011025/421599/Assessment-of-Turbulence-Model-Predictions-for-an.

(4) Computational turbulent flow characteristics in a centrifugal pump. https://pubs.aip.org/aip/adv/article/12/7/075025/2818977/Computational-turbulent-flow-characteristics-in-a.

(5) http://dx.doi.org/10.5293/IJFMS.2020.13.3.623.

(6) Effect of Blade Profile on the Performance of a Centrifugal Fan with .... https://www.jstage.jst.go.jp/article/ijfms/13/3/13_623/_pdf/-char/en.

(7) https://doi.org/10.3390/en16237864.