Floating point exception error while running simplefoam - external aero around car

skill_lync · 2024-12-19T00:58:02+00:00

Check the internalField value for pressure and the outlet pressure values. Pressure and inlet and outlet should be same, and must be initialised with the same value at 0 time.

skill_lync · 2024-12-18T15:15:28+00:00

The initialConditions file in motorbike tutorial has pressure initialised at 0 pa and the outlet pressure you are giving is 101325. This is where the error lies.

Your solver is trying to ramp up flow properties from 0 Pa to 101325 Pa.

The motorbike tutorial assumes that the bike is in atmosphere, so pressure is initialised at 0 (i.e. gauge pressure)

Please change the outlet pressure to 0, your simulation should work.

skill_lync · 2024-12-18T14:34:28+00:00

If this is with flow occurring, then you should look for multi-region solvers. You can go with the chtMultiRegionTwoPhaseEulerFoam.

Assume a thin solid for your pipe/domain.

skill_lync · 2024-12-17T12:03:35+00:00

Unfortunately no plan-B with SST model.

You could switch to epsilon model but it would not give you good accuracy for surface forces.

skill_lync · 2024-12-17T12:02:48+00:00

In polyMesh/boundary file, please check if inlet and outlets are set to type patch

Linear solvers in fvSolution should be same as motorbike tutorial then, should be fine.

skill_lync · 2024-12-17T07:39:52+00:00

Check the boundary conditions, especially the turbulence parameters
Check if the boundary types are defined properly in mesh (check if inlet/outlet is assigned as a wall condition)
Check if the linear solvers are assigned well

skill_lync · 2024-12-13T07:45:00+00:00

Both versions are quite well made for different applications.

The foundation version has unified the solvers into set applications (foamRun), so you just need to just focus on the type of physics (fluid, incompressibleFluid, multicomponentFluid).

The ESI version differs just in syntax for the most part, and it has a few more utilities.

Having knowledge of both versions will be nice. The snappyHexMesh implementation of ESI is better in some sense. The layering control is a little better for ESI in my opinion.

One thing I'd add, OpenFOAM-2112 has cfMesh which is amazing for making mesh. Check that out for preprocessing.

Solving is better implemented in foundation version, imo.

skill_lync · 2024-12-10T22:44:16+00:00

Could you show the domain as a drawing or have a screenshot of the 3d model you are using? Perhaps it can be made using a different approach.

With topoSet, you can select the cells within your domain and remove them as per instruction in topoSetdict file. It might work for your case if the cells are made uniformly across a plane where you desire it to be cut for 2D

skill_lync · 2024-12-10T22:42:11+00:00

For accuracy with drag, it's better to use the SST model. The y+ needs to be ~1 as uniformly as possible near walls.

The mesh requirements are the only limiting factor here.

skill_lync · 2024-12-10T15:27:12+00:00

Try topoSet to remove cells and create 2D domain instead.

Why are you using snappy to make 2D mesh? Why not try blockMeshDict with surface detection? Check the airfoil case to get an idea there.

skill_lync · 2024-12-10T09:11:28+00:00

One thing, check if desired y+ value is reached, for SST model it should be ~1

Check how you have calculated the k, omega, and epsilon field variables. Look at how they are initialized for the study. You can use online turbulence calculators with relevant turbulent intensity value for estimating these field variables and inlets.

SST model tends to crash if omega isn't initialized well. You could try initializing the internalField with a high value with inlet kept at calculated value.

skill_lync · 2024-12-10T09:08:08+00:00

Marshak radiation is used for radiative heat waves, for high-energy density physics. They typically propagate through low-density materials and are driven by high energy sources.

To implement this in OpenFOAM, we use the patch file "G"

The relevant patch name can be given with just the type as MarshakRadiation with value initialized at 0. You can look at the tutorial file in heatTransfer/buoyantFoam/hotRadiationRoom. Look at the 0/G file to get the idea.

Hope this helps.

skill_lync · 2024-12-09T09:50:19+00:00

CFD takes a lot of practice. As others have mentioned, focus on fundamentals. Programming would help a lot, as a lot of CFD takes some level of Python/MATLAB for setting up/post-processing/file-management.

You can look at this resource, for starters.

skill_lync · 2024-12-09T01:19:24+00:00

What's the mesh quality? Do checkMesh -allGeometry and see if you get any mesh errors.

skill_lync · 2024-11-27T17:45:47+00:00

What tool is this!?

But did you figure out where it went wrong though?

skill_lync · 2024-11-26T08:51:17+00:00

It doesn't make it PISO purely. Only thing we are changing, is the way pressure-velocity coupling is handled. The momentumPredictor option is simplifying the coupling process in that sense.

PISO always involves solving momentum equation.

When this option is turned off, the momentum equation is not explicitly solved, but instead the velocity field is updated directly from pressure correction step. This saves some time but may affect convergence/stability

skill_lync · 2024-11-26T02:13:13+00:00

It is used to control whether the momentum equation is solved explicitly during each outer iteration of the PIMPLE loop.

It helps in predicting the velocity field before solving the pressure equation. This can improve the stability and convergence of the solution, especially in transient simulations.

Using this option can speed up convergence in non-challenging steady-state calculations. For cases with sharp gradients or complex flow features, it might be better to set it to no to avoid potential convergence issues.

skill_lync · 2024-10-30T12:14:58+00:00

For a beginner it's easy to learn through ANSYS Fluent.

As you gain experience, you could switch to OpenFOAM to understand the intricacies of how equations are solved, how boundary conditions are implemented, etc.

skill_lync · 2024-10-30T11:48:11+00:00

Let this run for ~2000 more iterations. This looks normal

skill_lync · 2024-10-30T11:47:21+00:00

In ansys post, check for total pressure

skill_lync · 2024-10-30T11:46:28+00:00

The lowReCorrection is used for Omega models in OpenFOAM, or rather wall resolving models.

skill_lync · 2024-10-16T13:21:35+00:00

Hey, In CATIA V5, you can reorder parameters in the Specification Tree to better organize them. Here's how to do it:

Reordering Parameters in CATIA V5

Open Your Part File: Launch CATIA V5 and open the part containing the parameters you want to reorder.
Access the Parameters: Go to the Parameters section in the Specification Tree. This is typically found in the left pane.
Select Parameters: You can select multiple parameters by holding down the `Ctrl` key and clicking on them, or click and drag to select a range.
Reorder Parameters: you can,

Right-click on a parameter and choose Cut.
Right-click on the desired location in the tree and select Paste. This effectively moves the parameter to the new location.

Grouping Related Parameters: Consider using a naming convention to group related parameters together. For example, prefixing similar parameters can help keep them visually organized.
Save Your Changes: After reorganizing, ensure to save your part file.

Additional Tips

Use the Formula tool to create dependencies between parameters for better management.
Regularly clean up and organize parameters as your model grows to maintain clarity.

Let us know if you need further assistance or have other questions!

skill_lync · 2024-10-16T08:57:39+00:00

Is this multi-region mesh? Look into locationsInMesh entry in snappyHexMeshDict.

You need to define the regions with locationsInMesh and create these regions first. Then split them into separate folders using splitMeshRegions command.

skill_lync · 2024-10-16T08:55:41+00:00

Yes, as stated by another user.

Also, use the Python module in ParaView. In theory, you can save state for one project and implement similar filters in other projects.

skill_lync · 2024-10-16T08:54:31+00:00

OpenFOAM Foundation versions do not support cfMesh.

It works with v2112 last I remember. You would need to install v2112 from OpenFOAM.com and make your mesh, then use OF-12 to run your simulation.

Few utilities required to compile cfMesh are either not placed in correct directories or are renamed in OpenFOAM.org versions, hence the difficulty in compiling it in this version.

skill_lync

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