💥💥💥 What is Open Modelica and what is used for?

 Open Modelica is a free and open source environment for modeling, simulating, optimizing and analyzing complex dynamic systems using the Modelica language¹. Modelica is a declarative, object-oriented language for modeling physical systems that can involve multiple domains such as mechanical, electrical, thermal, fluid, and control².

Open Modelica is used for industrial and academic purposes, such as engineering design, research, education, and training. It provides various tools and applications, such as:

- OMC: The OpenModelica Compiler, which translates Modelica code into executable code and supports the Functional Mockup Interface (FMI) standard for model exchange and co-simulation¹.

- OMEdit: The OpenModelica graphical user interface, which allows users to create, edit, simulate, and debug Modelica models using a graphical or textual editor¹.

- OMShell: The OpenModelica command-line interface, which allows users to interact with the OMC and perform various operations on Modelica models¹.

- OMNotebook: The OpenModelica interactive notebook, which allows users to combine Modelica code, documentation, and simulation results in a single document¹.

- OMPython: The OpenModelica Python interface, which allows users to access the OMC from Python scripts and use Python libraries for data analysis and visualization¹.

- OMMatlab: The OpenModelica Matlab interface, which allows users to access the OMC from Matlab and use Matlab functions and toolboxes for data analysis and visualization¹.

You can learn more about Open Modelica and its features, tools, applications, and how to join the project and contribute by visiting their official website¹ or their Wikipedia page³. 

Source: 

(1) OPENMODELICA. https://openmodelica.org/.

(2) Download Windows - OPENMODELICA. https://openmodelica.org/download/download-windows/.

(3) OpenModelica - Wikipedia. https://en.wikipedia.org/wiki/Openmodelica.

What is the difference between Modelica and Simulink?

The difference between Modelica and Simulink is that they use different approaches to model and simulate physical systems. Modelica uses an equation-based or acausal approach, while Simulink uses a signal flow-based or causal approach¹.

In an equation-based or acausal approach, the components are connected by physical connectors that represent physical quantities such as force, voltage, or temperature. The components do not have fixed inputs and outputs, but rather define equations that describe the relationship between the physical quantities. The direction of the information flow is not predefined, but determined by the solver that solves the system of equations. This allows for more flexibility and modularity in modeling complex systems that involve multiple domains and feedback loops².

In a signal flow-based or causal approach, the components are connected by signals that represent data values such as numbers, vectors, or matrices. The components have fixed inputs and outputs, and compute the outputs from the inputs by explicit assignments and operations. The direction of the information flow is predefined and cannot be changed. This requires the user to specify how the signals interact with each other and how to handle algebraic loops and discontinuities³.

Both approaches have their advantages and disadvantages, depending on the type and complexity of the system to be modeled and simulated. Some of the advantages of Modelica over Simulink are:

- Modelica is an open-source and standardized language that can be used in various simulation environments, while Simulink is a proprietary and platform-dependent tool that requires Matlab.

- Modelica allows for more natural and intuitive modeling of physical systems, as it does not require the user to define the causality and direction of the information flow.

- Modelica supports object-oriented and hierarchical modeling, which enables reuse and inheritance of components and models.

- Modelica supports the Functional Mockup Interface (FMI) standard, which enables model exchange and co-simulation with other tools that support FMI.

Some of the advantages of Simulink over Modelica are:

- Simulink is more mature and widely used in the industry and academia, and has a large user community and support network.

- Simulink has a user-friendly and graphical interface, and integrates well with Matlab and other MathWorks products.

- Simulink offers a range of solutions and toolboxes for different applications and domains, such as control design, signal processing, embedded systems, and machine learning.

- Simulink has more advanced and robust solvers and algorithms, and supports code generation and hardware-in-the-loop testing.

Source: 

(1) Modelica vs Simulink - TLK Energy. https://tlk-energy.de/blog-en/modelica-vs-simulink.

(2) Compare Modelica vs. Simulink | G2. https://www.g2.com/compare/modelica-vs-simulink.

(3) Matlab Simscape vs Simulink vs PDE-Toolbox/Ansys/Comsol. https://stackoverflow.com/questions/56992867/matlab-simscape-vs-simulink-vs-pde-toolbox-ansys-comsol.

Can I model Conjugate Heat Transfer in Open Modelica?

Yes, you can model conjugate heat transfer in Open Modelica, which is the process of heat transfer between a solid and a fluid in contact with each other. To do so, you need to use the components from the Modelica.Thermal.HeatTransfer library, which contains models for 1-dimensional heat transfer with lumped elements¹. You can also use the components from the Buildings.HeatTransfer.Convection library, which contains models for convective heat transfer between a solid and a fluid².

For example, you can use the ThermalConductor component to model the heat conduction in the solid, the ConvectiveHeatTransfer component to model the heat transfer coefficient between the solid and the fluid, and the HeatCapacitor component to model the heat capacity of the solid and the fluid. You can also use the FixedTemperature component to model the boundary conditions of the solid and the fluid, such as the inlet and outlet temperatures¹.

You can find some example models that demonstrate the usage of these components in the Modelica.Thermal.HeatTransfer.Examples package³. For instance, the Motor example shows how to model the heating of an electrical motor, which involves conjugate heat transfer between the winding, the core, and the air³. You can also check out this question on Stack Overflow that shows how to model the convective heat transfer of the fluid inside a dynamic pipe⁴.

Source: 

(1) Modelica.Thermal.HeatTransfer.UsersGuide. https://doc.modelica.org/Modelica%204.0.0/Resources/helpDymola/Modelica_Thermal_HeatTransfer_UsersGuide.html.

(2) Buildings.HeatTransfer.Convection. https://simulationresearch.lbl.gov/modelica/releases/v9.1.0/help/Buildings_HeatTransfer_Convection.html.

(3) Modelica.Thermal.HeatTransfer.Examples - Maplesoft. https://www.maplesoft.com/documentation_center/online_manuals/modelica/Modelica_Thermal_HeatTransfer_Examples.html.

(4) Question about convection heat transfer in the dynamic pipe of the .... https://stackoverflow.com/questions/71123874/question-about-convection-heat-transfer-in-the-dynamic-pipe-of-the-modelica-stan.