What is, and when to use MRF method in Ansys Fluent

The MRF method stands for multiple reference frame, which is a way of modeling a rotating fan or any other moving part in a fluid flow simulation. The MRF method allows you to divide your domain into different zones, each of which can have a different rotational or translational speed. For example, you can create a zone for the fan region that is rotating at a certain angular velocity, and another zone for the rest of the domain that is stationary.

The MRF method solves the flow equations in each zone using the moving reference frame equations, which account for the relative motion between the zones. The moving reference frame equations are derived from the Navier-Stokes equations by applying a coordinate transformation that accounts for the rotation and/or translation of the reference frame. You can find more details about the derivation and formulation of the moving reference frame equations in this section⁶ of the Ansys Fluent Theory Guide.

At the interfaces between zones, a local reference frame transformation is performed to enable flow variables in one zone to be used to calculate fluxes at the boundary of the adjacent zone. This ensures that the flow is continuous and conservative across the interfaces. For more information about the MRF interface formulation, see this section⁵ of the Ansys Fluent User's Guide.

The MRF method is a steady-state approximation, which means that it assumes that the flow does not change over time. This makes it simpler and faster to solve than other methods that capture transient effects or interactions between the fan and the fluid. However, the MRF method also has some limitations, such as not being able to model unsteady phenomena like blade flutter or stall, or not being able to handle complex geometries or mesh motions.

To use the MRF method in Ansys Fluent, you need to follow some general steps:

- Create or import a geometry of the fan and the fluid domain in Ansys DesignModeler or any other CAD software.

- Mesh the geometry using Ansys Meshing or any other meshing software. Make sure to create a separate zone for the fan region and apply appropriate boundary layer and inflation settings.

- Import the mesh into Ansys Fluent and set up the solver settings, such as the turbulence model, the operating pressure, and the solution methods.

- Define the boundary conditions for the inlet, outlet, walls, and fan regions. For

the fan region, you need to specify a rotating wall boundary condition with a constant angular velocity. You also need to enable the MRF option for the fan zone and define its axis of rotation.

- Initialize and run the simulation until convergence. You can monitor the residuals, forces, moments, and other quantities of interest during the solution process.

- Post-process and visualize the results using Ansys Fluent or any other post-processing software. You can plot contours, vectors, streamlines, iso-surfaces, and other graphical features to analyze the flow field and heat transfer around the fan.

If you want to learn more about how to uset he MRF method in Ansys Fluent,you can watch some video tutorials on YouTube that demonstrate this process step by step. For example,you can watch this video¹ by Alpha Omega Product Development Systems,which shows how to model an axial fan in Ansys Fluent using the MRF method. You can also watch this video² by CFD NINJA, which shows how to model an axial fan in Ansys Fluent using both the MRF and sliding mesh methods.

I hope this answer helps you understand more about the MRF method in Ansys Fluent. If you have any other questions, feel free to ask me. 😊

Source:

(1) ANSYS FLUENT 12.0 Theory Guide - 2.3.1 The Multiple Reference ... - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/th/node33.htm.

(2) ANSYS FLUENT 12.0 User's Guide - 10.3.1 The Multiple Reference ... - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node370.htm.

(3) Ansys Fluent Tutorial for beginners | Multiphase Flow | Three Phases | Ansys Workbench. https://www.youtube.com/watch?v=QgQTaXuPmbI.

(4) Ansys Fluent tutorial for beginners. https://www.youtube.com/watch?v=Xq0WsxL0hZQ.

(5) Performing Parametric Analyses Using Ansys Fluent. https://www.youtube.com/watch?v=4bZqL9ZNJwA.

(6) ANSYS Fluent Tutorial | Multiple Reference Frame (MRF) | ANSYS .... https://www.youtube.com/watch?v=A3bnO5r2SWQ.

(7) undefined. https://files.mecht.in.

(8) undefined. https://www.instagram.com/mech_tech.90/.

(9) https://www.facebook.com/mechtechpage/.

(10) http://www.ansys-tutor.blogspot.com.

If U want more interesting topics please feel free to click links below 

Rules for good quality mesh in Ansys Fluent

How to avoid overflow error in Ansys Fluent

Types of supports and examples - Ansys Static Structural

Rules for good quality mesh in Ansys Fluent

 To generate a good quality mesh for Ansys Fluent, you need to follow some essential rules that are based on the mesh quality criteria and the physics of the problem. Here are some of the rules:

- Choose the appropriate mesh type for your problem. Ansys Fluent supports different types of meshes, such as tetrahedral, hexahedral, polyhedral, and mosaic. Each type has its own advantages and disadvantages, depending on the geometry, flow features, and solver settings. For example, tetrahedral meshes are easy to generate and can conform to complex shapes, but they may have lower accuracy and stability than hexahedral meshes. Polyhedral meshes can reduce the cell count and improve the solution convergence, but they may require more memory and CPU time than tetrahedral meshes. Mosaic meshes can combine the benefits of polyhedral and hexahedral meshes by using polyhedral elements in the bulk and hexahedral elements near the walls¹.

- Minimize the mesh skewness and aspect ratio. Mesh skewness is a measure of how far a cell deviates from an ideal shape, such as an equilateral triangle or a regular hexagon. Mesh aspect ratio is a measure of how stretched a cell is. High skewness and aspect ratio can degrade the solution accuracy and convergence, as well as increase the numerical diffusion and errors. Ansys Fluent provides tools to check and report the mesh quality based on these criteria²⁴. You can also use mesh adaption and refinement techniques to improve the mesh quality in regions of high skewness or aspect ratio¹.

- Resolve the boundary layer and other flow features. The boundary layer is the thin layer of fluid near the wall where the velocity changes from zero to the free-stream value. The boundary layer has a significant impact on the drag, heat transfer, and separation of the flow. To capture the boundary layer effects accurately, you need to use a fine mesh near the wall that satisfies the y+ criterion. The y+ value is a dimensionless parameter that indicates how well the mesh resolves the viscous sublayer, which is the innermost part of the boundary layer where the flow is laminar. Depending on the turbulence model and the wall treatment used, you may need to have a y+ value below 1, between 1 and 5, or above 30¹. You can use Ansys Fluent to calculate and report the y+ values on your mesh². Besides the boundary layer, you also need to resolve other important flow features, such as shear layers, separated regions, shock waves, and mixing zones. You can use mesh sizing functions, inflation layers, or body of influence to control the mesh density and distribution in these regions¹.

- Optimize the mesh size and performance. The mesh size affects not only the solution accuracy, but also the computational cost and time. A finer mesh can resolve more details of the flow, but it also requires more memory and CPU time to solve. Therefore, you need to find a balance between the mesh resolution and the computational efficiency. You can use Ansys Fluent to estimate the memory and CPU time required for your mesh². You can also use parallel processing, hybrid meshing, or mesh morphing techniques to speed up your simulation¹.

These are some of the essential rules to generate a good quality mesh for Ansys Fluent. I hope this helps you with your simulation project 😊. If you want to learn more about Ansys Fluent meshing, you can check out some of these online courses³⁶ or read some of these documents⁴⁵. Have a nice day!

Source:

(1) Advanced Ansys Fluent Meshing | Ansys Training. https://www.ansys.com/training-center/course-catalog/fluids/advanced-ansys-fluent-meshing.

(2) Ansys Meshing | 2D/3D Mesh Generation and Analysis for FEA, CFD. https://www.ansys.com/products/meshing.

(3) ANSYS FLUENT 12.0 User's Guide - 6.2.2 Mesh Quality - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node167.htm.

(4) Ansys Fluent Meshing Learning Track | Ansys Courses. https://courses.ansys.com/index.php/learning-track/ansys-fluent-meshing-watertight-geometry-workflow/.

(5) How to Verify Mesh Quality in ANSYS Workbench - FEA Tips. https://featips.com/2021/05/07/how-to-verify-mesh-quality-in-ansys-workbench/.

(6) Chapter 15. Reporting Mesh Statistics - univ-reims.fr. https://romeo.univ-reims.fr/documents/fluent/tgrid/ug/chp15.pdf.

Cake Story 

There was once a family of four: a father, a mother, a son, and a daughter. They loved to eat cake, but they had different preferences for the flavors and the toppings. The father liked chocolate cake with whipped cream, the mother liked vanilla cake with strawberries, the son liked carrot cake with cream cheese frosting, and the daughter liked lemon cake with blueberries.

One day, they decided to bake a cake together for their anniversary. They agreed to make a four-layer cake, each layer with a different flavor and topping. They spent hours in the kitchen, mixing, baking, cooling, and decorating the cake. They were very proud of their creation and couldn't wait to taste it.

They brought the cake to the dining table and admired it for a while. Then they decided to cut it into four equal pieces, one for each of them. The father took a knife and sliced the cake vertically, making two halves. Then he sliced one of the halves horizontally, making two quarters. He gave one quarter to himself and one quarter to his wife. He was about to slice the other half of the cake when he realized that he had made a mistake.

He had cut the cake in such a way that each piece had only one flavor and topping. His piece had only chocolate and whipped cream, his wife's piece had only vanilla and strawberries, and the remaining pieces had only carrot and cream cheese or lemon and blueberries. He had not mixed the flavors and toppings as they had intended.

He looked at his family and saw their disappointed faces. They had all wanted to try a bit of each flavor and topping, not just their own favorites. He felt sorry for ruining their anniversary cake. He apologized profusely and asked them what they wanted to do.

The mother thought for a moment and then smiled. She said that they could still enjoy the cake if they shared their pieces with each other. She suggested that they cut each piece into four smaller pieces, so that everyone could have one small piece of each flavor and topping. She said that this way, they could taste the variety of the cake and also appreciate each other's preferences.

The father agreed with his wife's idea and quickly cut the pieces as she suggested. He gave one small piece of each flavor and topping to each member of his family. They all thanked him and took their plates. They then proceeded to eat their cake with delight.

They found that the cake was delicious and that each flavor and topping complemented the others. They also enjoyed sharing their opinions and preferences with each other. They realized that they had learned something new about themselves and their family through this experience.

They finished their cake and hugged each other. They thanked each other for making the cake together and for being flexible and generous with their choices. They agreed that this was the best anniversary cake they ever had.

The end 😊

If U want more interesting posts go to links below 

How to avoid overflow error in Ansys Fluent

Types of supports and examples - Ansys Static Structural

How to deal with peak stresses on Ansys Structural (Mechanical)

How to avoid overflow error in Ansys Fluent

 An overflow error in Ansys Fluent can occur when the solver encounters a numerical instability or a divergence in the solution. This can be caused by various factors, such as:

- Inappropriate boundary conditions or initial conditions

- Poor mesh quality or resolution

- Incorrect physical models or parameters

- Large time steps or under-relaxation factors

- Round-off errors or machine precision limitations

To avoid overflow errors, you can try some of the following suggestions:

- Check your geometry and mesh for any errors or defects. You can use the Fault Detection tool in Design Modeler² or the Mesh Check tool in Fluent¹ to identify and fix any problems.

- Refine your mesh to capture the important features and regions of your domain. You can use the Proximity and Curvature meshing option in ANSYS Mesher² to generate a high-quality mesh that adapts to the geometry shape.

- Initialize your solution with reasonable values that are close to the expected solution. You can use the Hybrid Initialization option in Fluent to initialize the flow variables based on the boundary conditions.

- Choose the appropriate physical models and parameters for your problem. You can consult the Fluent User's Guide or the Fluent Theory Guide for guidance on selecting the best models for your case.

- Reduce your time step size or your under-relaxation factors to improve the stability and convergence of your solution. You can use the Courant Number option in Fluent to automatically adjust the time step based on the local flow velocity and mesh size.

- Increase the solver precision or switch to double precision to reduce the round-off errors and increase the accuracy of your solution. You can change the solver precision in the Solver Settings panel in Fluent.

I hope these tips help you avoid overflow errors in Ansys Fluent. If you have any further questions, please feel free to ask me. 😊

Source: 

(1) ANSYS Fluent - Tips, Tricks, and Troubleshooting – Nimbix. https://support.nimbix.net/hc/en-us/articles/360044738671-ANSYS-Fluent-Tips-Tricks-and-Troubleshooting.

(2) Overflow error - Ansys Learning Forum. https://forum.ansys.com/forums/topic/overflow-error/.

(3) Floating Point Exception (Core Dumped): How To Fix This Error. https://www.positioniseverything.net/floating-point-exception-core-dumped/.

If U want to learn more interesting topics please ser links below 

Types of supports and examples - Ansys Static Structural

How to prepare strength (Structural) and cfd analysis in Ansys Mechanical - Rotating Elements

How to deal with peak stresses on Ansys Structural (Mechanical)

Types of supports and examples - Ansys Static Structural

Supports are used to represent parts that are not present in the model but are interacting with it. Supports help truncate the domain, which helps in efficiently obtaining numerically accurate results without modeling parts of the geometry that are not of primary interest. There are different types of support available, among which you need to choose the appropriate one for your analysis. Here are some of the common types of supports and their explanations:

- **Fixed Support**: This type of support constrains all the degrees of freedom of the selected entity (body, face, or edge). It means that the entity cannot move or rotate in any direction. Fixed support is equivalent to applying zero displacement to all directions. Fixed support is useful for modeling rigid connections or supports that do not allow any movement. For example, you can use fixed support to model a bolted joint or a clamped beam.

- **Displacement Support**: This type of support specifies a zero or non-zero displacement to any of the three orthogonal directions (X, Y, Z) of the selected entity. It means that the entity can move only in the specified direction and amount, while being constrained in the other directions. Displacement support is useful for modeling prescribed displacements or deformations that are known in advance. For example, you can use displacement support to model a spring or a thermal expansion.

- **Frictionless Support**: This type of support constrains translational movement in the direction normal to the surface of the selected entity (face or edge). It means that the entity can slide freely along the surface, but cannot separate from it or penetrate into it. Frictionless support is useful for modeling smooth contact surfaces or supports that do not resist tangential forces. For example, you can use frictionless support to model a roller or a slider.

- **Cylindrical Support**: This type of support constrains translational movement in two directions (radial and axial) and rotational movement in one direction (circumferential) of the selected entity (face or edge). It means that the entity can rotate freely around an axis, but cannot move along or away from it. Cylindrical support is useful for modeling cylindrical or circular surfaces or supports that allow rotation but not translation. For example, you can use cylindrical support to model a pin or a hinge.

- **Compression Only Support**: This type of support constrains translational movement in the direction normal to the surface of the selected entity (face or edge) only when it is in compression. It means that the entity can separate from the surface when it is in tension, but cannot penetrate into it when it is in compression. Compression only support is useful for modeling contact surfaces or supports that do not resist tensile forces. For example, you can use compression only support to model a foundation or a soil.

- **Elastic Support**: This type of support applies a linear elastic spring or damper to the selected entity (body, face, or edge). It means that the entity can move or rotate in any direction, but with a resistance proportional to its stiffness or damping coefficient. Elastic support is useful for modeling flexible connections or supports that have some degree of compliance. For example, you can use elastic support to model a rubber bushing or a shock absorber.

- **Remote Displacement Support**: This type of support applies a displacement to a remote location and transfers it to the selected entity (body, face, or edge) through rigid links. It means that the entity can move or rotate in any direction as specified by the remote displacement, while being rigidly connected to the remote location. Remote displacement support is useful for modeling complex loading conditions or supports that are far away from the model. For example, you can use remote displacement support to model a wind load or a seismic load.

I hope this helps you understand the types of supports in Ansys Static Structural. If you want more details or examples, you can check out these sources below.  If you have any other questions, feel free to ask me 😊.

Source: 

(1) Types of Supports in Static Structural Analysis. https://www.graspengineering.com/types-of-supports-in-static-structural-analysis/.

(2) Types of Supports in Static Structural Analysis. https://www.graspengineering.com/types-of-supports-in-static-structural-analysis/.

(3) Determining which Support to Use - ANSYS Innovation Courses. https://courses.ansys.com/index.php/courses/structural-boundary-conditions/lessons/determining-which-support-to-use-lesson-1/.

(4) Determining which Support to Use - ANSYS Innovation Courses. https://courses.ansys.com/index.php/courses/structural-boundary-conditions/lessons/determining-which-support-to-use-lesson-1/.

(5) Boundary Conditions and Explanations in ANSYS - Mechead.com. https://www.mechead.com/boundary-conditions-and-explanations-in-ansys/.

(6) Boundary Conditions and Explanations in ANSYS - Mechead.com. https://www.mechead.com/boundary-conditions-and-explanations-in-ansys/.

(7) Defining Elastic Supports In ANSYS Mechanical Analyses - ML. https://mechanicalland.com/defining-elastic-supports-in-ansys-mechanical-analyses/.

(8) Defining Elastic Supports In ANSYS Mechanical Analyses - ML. https://mechanicalland.com/defining-elastic-supports-in-ansys-mechanical-analyses/.

How to use these supports from Ansys Static Structural. Here are some scenarios  that illustrate the application of different types of supports:

- Fixed Support: Suppose you want to model a cantilever beam that is fixed at one end and has a point load at the other end. You can use a fixed support to constrain all the degrees of freedom of the face where the beam is attached to the wall. This will prevent the beam from moving or rotating in any direction. You can then apply a force load to the face where the point load is acting. The screenshot below shows how to apply a fixed support in Ansys Workbench¹.


- Displacement Support: Suppose you want to model a spring that is stretched by a known amount. You can use a displacement support to specify a non-zero displacement in the direction of stretching for the face where the spring is attached to a rigid body. This will allow the spring to deform in that direction, while being constrained in the other directions. You can then apply a fixed support to the other face of the spring to prevent it from moving or rotating. The screenshot below shows how to apply a displacement support in Ansys Workbench².


- Frictionless Support: Suppose you want to model a roller that is resting on a horizontal surface and has a vertical load applied to it. You can use a frictionless support to constrain the translational movement in the normal direction for the face where the roller is in contact with the surface. This will prevent the roller from separating from or penetrating into the surface, while allowing it to slide freely along it. You can then apply a pressure load to the face where the vertical load is acting. The screenshot below shows how to apply a frictionless support in Ansys Workbench³.


- Cylindrical Support: Suppose you want to model a hinge that connects two bars and allows them to rotate around an axis. You can use a cylindrical support to constrain the translational movement in the radial and axial directions and the rotational movement in the circumferential direction for the face where the hinge is attached to one of the bars. This will prevent the bar from moving along or away from the axis, while allowing it to rotate around it. You can then apply a moment load to the other bar to induce rotation. The screenshot below shows how to apply a cylindrical support in Ansys Workbench.

![Cylindrical Support]

- Compression Only Support: Suppose you want to model a column that is supported by a foundation and has an axial load applied to it. You can use a compression only support to constrain the translational movement in the normal direction for the face where the column is in contact with the foundation, only when it is in compression. This will prevent the column from penetrating into the foundation when it is compressed, while allowing it to separate from it when it is in tension. You can then apply a force load to the face where the axial load is acting. The screenshot below shows how to apply a compression only support in Ansys Workbench.

![Compression Only Support]

- Elastic Support: Suppose you want to model a rubber bushing that connects two shafts and has some degree of compliance. You can use an elastic support to apply a linear elastic spring or damper to the face where the bushing is attached to one of the shafts. This will allow the shaft to move or rotate in any direction, but with a resistance proportional to its stiffness or damping coefficient. You can then apply a torque load to the other shaft to induce rotation. The screenshot below shows how to apply an elastic support in Ansys Workbench.

![Elastic Support]

- Remote Displacement Support: Suppose you want to model a wind turbine blade that is subjected to a wind load that varies along its length. You can use a remote displacement support to apply a displacement to a remote location and transfer it to the face where the blade is attached to the hub through rigid links. This will allow the blade to move or rotate in any direction as specified by the remote displacement, while being rigidly connected to the remote location. You can then define a table or function for the remote displacement that represents the wind load profile. The screenshot below shows how to apply a remote displacement support in Ansys Workbench.

![Remote Displacement Support]

I hope these examples help you understand how to use these supports from Ansys Static Structural. If you want more details or examples, you can check out these sources: [Types of Supports in Static Structural Analysis](^2^) ², [Types of Supports in Structural Analysis - YouTube](^3^) ³, [Lecture 7 Static Structural Analysis - Rice University](^1^) ¹, and [Defining Elastic Supports In ANSYS Mechanical Analyses - ML] . If you have any other questions, feel free to ask me 😊.

Source:

(1) Lecture 7 Static Structural Analysis - Rice University. https://www.clear.rice.edu/mech517/WB16/lectures_trainee/Mechanical_Intro_16.0_L07_Static.pdf.

(2) Lecture 7 Static Structural Analysis - Rice University. https://www.clear.rice.edu/mech517/WB16/lectures_trainee/Mechanical_Intro_16.0_L07_Static.pdf.

(3) Types of Supports in Static Structural Analysis. https://www.graspengineering.com/types-of-supports-in-static-structural-analysis/.

(4) Types of Supports in Static Structural Analysis. https://www.graspengineering.com/types-of-supports-in-static-structural-analysis/.

(5) Types of Supports in Structural Analysis - YouTube. https://www.youtube.com/watch?v=yiBn0iaV4z0.

(6) Types of Supports in Structural Analysis - YouTube. https://www.youtube.com/watch?v=yiBn0iaV4z0.

(7) Types of Supports in Static Structural Analysis. https://www.graspengineering.com/types-of-supports-in-static-structural-analysis/.

(8) Types of Supports in Structural Analysis - YouTube. https://www.youtube.com/watch?v=yiBn0iaV4z0.

(9) Lecture 7 Static Structural Analysis - Rice University. https://www.clear.rice.edu/mech517/WB16/lectures_trainee/Mechanical_Intro_16.0_L07_Static.pdf.

If U want to learn more about ansys check links below 

How to deal with peak stresses on Ansys Structural (Mechanical)

How to prepare strength (Structural) and cfd analysis in Ansys Mechanical - Rotating Elements

How to... fix "gui-domain-label: no domain selected" in Ansys Fluent and MEMERR in CFX

How to deal with peak stresses on Ansys Structural (Mechanical)

 - **Stress averaging**: This method is used to smooth out the stress distribution by averaging the stresses over a certain area or volume. This can reduce the effect of local stress concentrations and provide a more realistic estimate of the average stress in the structure. However, this method may also hide some important stress variations and details, and may not be applicable for complex geometries or non-linear problems. You can read more about this method [here](^1^).

- **Submodeling**: This method is used to perform a detailed analysis of a small region of interest within a larger model. This can increase the accuracy and resolution of the solution in the region where peak stresses occur, without increasing the computational cost and time for the whole model. However, this method requires careful selection of the submodel boundaries and loading conditions, and may not capture the global effects of the structure. You can read more about this method [here](^2^).

- **Singularity elimination**: This method is used to modify the geometry or boundary conditions of the model to eliminate or reduce the singularities that cause peak stresses. Singularities are points or lines where the stress becomes infinite or undefined, such as sharp corners, re-entrant angles, or point loads. By rounding off the corners, adding fillets, or distributing the loads, the singularities can be avoided or minimized. However, this method may also alter the actual behavior of the structure and introduce errors or uncertainties. You can read more about this method [here](^3^).

These are some of the methods that can be used to deal with peak stresses on ANSYS. I hope this helps you understand them better. I

Source:

(1) Understanding and Dealing with Artificially High Stress Using Ansys .... https://www.youtube.com/watch?v=iTqPgcTurXc.

(2) Stress Analysis with Ansys Mechanical. https://courses.ansys.com/index.php/courses/stress-analysis-with-ansys-mechanical/.

(3) What is Stress Linearization? - graspengineering.com. https://www.graspengineering.com/what-is-stress-linearization/.

(4) undefined. https://bing.com/search?q=.

If U want more intresting entries try links below

Static structural analysis (simulation) in Ansys - for beginners

How to add / generate subdomain on existing geometry - Ansys Design Modeler

Investigation of the influence of conductivity of two-component geometry in Ansys Transient Thermal

Jak szybko i łatwo modyfikować model/ geometrię w Design Modeler Ansys

 W dzisiejszym wpisie chciałbym pokazać jak łatwo i szybko zmodyfikować geometrię do obliczeń wytrzymałościowych w modułach konstrukcyjnych (Structural ). Wystarczą dwa kroki, aby łatwo zmienić topologię modelu w module Design Modeler.

Jak przesunąć i zmienić skalę części w geometrii — Design Modeler

Wpływ różnych kierunków przewodnictwa cieplnego materiałów na rozkład temperatury - Ansys Transient Thermal (Mechanical) część 1

 W dzisiejszym wpisie chciałbym pokazać samouczek w Transient Thermal dotyczący analizy wpływu przewodnictwa ze względu na różne położenie tych samych warunków brzegowych dla tej samej geometrii.

Wpływ przewodności w Ansys Transient Thermal