This section is going to explain how to use SimScale to run for computational fluid dynamics (CFD) simulations of a solar car. It will cover the basics of a simple, steady-state case and discuss some of the more advanced settings, but will assume some knowledge of fluids.
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This information has been compiled from what I was taught by more experienced members, my own research, and my experiences while simulating MSXIV.
If you want to read about CFD simulations in ANSYS Fluent, there’s this page from the development of MSXII. That page is a great resource in general as it also discusses the workflow of CFD simulations and explains settings concisely.
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As of the time of writing, our results have not been validated. I will update this section when we have physical data and measurements from MSXIV but until then keep this in mind. |
What is SimScale?
SimScale is a web-based simulation platform, which allows the user to simulate how their CADed design would behave instead of having to build a prototype of their design and test it. What sets SimScale apart from the other simulation programs (like ANSYS) is that SimScale takes advantage of cloud computing. CFD simulations are usually very computationally demanding, which can take days to run on an average computer. Cloud computing means users can send their simulations to SimScale, who use really powerful computers to finish moderately large simulations in a couple of hours, and send the results back. There are also several other benefits to using SimScale, such as having a simple and intuitive user interface, access to help from simulation experts, and educational tools to learn about simulation theory.
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In the top bar, there is a drop-down menu for Learning. Go here for tutorials, webinars, and documentation. In the top right, you can log in or sign up for a new account. Free accounts (also called community accounts) are limited to 16 computing cores and 3,000 core hours. This account type is great for personal accounts where you can learn how to use SimScale and test things out.
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The team was sponsored during the design of MSXIV, which granted us a the team an account with a 32 core limit, over 40,000 core hours, and private projects. That may seem like an excessive number of core hours, especially when compared to a community account, however CFD simulations can easily consume that many hours. It is recommended that In the future, I would recommend planning core hour use is planned out and that reserving a portion of the team account’s core hours are reserved for advanced simulations (Cross winds, rotating wheels, ventilation, etc) if these results are desired. Tips for reducing core hour use will be discussed throughout.
Creating/Opening a Project
After logging in, hover over your username/profile icon in the upper right, then select Dashboard in the drop-down menu. Your dashboard may be a little empty if you have a new account but this is where you can access all your projects. You can also see your forum activity, core hours remaining, and the status of running simulations on the right side. To create a new project, click New Project.
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Fill in the Project Title and Description, the rest can be filled in as desired or left alone. On eligible accounts projects can be specified as private here. Click Create.
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A naming system should be created and used to keep the account organized. After running several simulations, it becomes very difficult to remember the differences between each one. |
To open an existing project, locate the project tile in the Dashboard and click on the arrow in the upper right corner of the tile. Clicking elsewhere on the tile will allow you to preview the project and give options such as editing the project, sharing it, duplicating it, or deleting it.
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 (I’m not suggesting this is a perfect naming system, but it’s better than several of the other projects on the team account.) |
The workflow can be grouped into 4 categories: uploading geometry, meshing, simulating, and post-processing.
Uploading Geometry
Once the project is open, there is a navigation panel on the left which will display all the settings to setup and run the simulation. Begin by uploading a CAD file of the geometry to simulate by clicking on the plus symbol beside Geometries (Slightly different in a new project, SimScale will prompt you to upload your first geometry). Select the appropriate file(s), they should appear under the Import List.
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The arrow to the left of the file will give some advanced options for the upload. I never needed these, but keep them in mind if you want SimScale to handle the geometry differently. |
Finish by clicking Import in the bottom left of the pop-up window.
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 Pop-up prompt when the project is brand new  Use the navigation panel for future uploads, clicking on the plus symbol will bring up the same prompt as in the previous image.  Selecting a file will add it to the import list. Make sure the correct file type (e.g. Solidworks, STEP, IGES) is displayed beneath the name. SimScale has interpreted files as the wrong file type before. |
Create Simulation
Once the geometry is uploaded, the simulation can be created by clicking the plus symbol beside Simulations. For CFD simulations at low speeds (Mach number less than 0.3) select Incompressible and click Create Simulation.
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Several more options will appear in the navigation panel. Meshing, simulating, and post-processing will be discussed in their own pages.
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I’ll divide the simulation workflow into 4 subsections, each one must be completed before moving on to the next one: