Problem with BreakingDam3D
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- This topic has 5 replies, 2 voices, and was last updated 2 weeks ago by stonepreston.
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January 29, 2025 at 8:23 pm #9811stoneprestonParticipant
Hello,
I am brand new at openLB and am running the examples. The dam break examples are close to what I would like to simulate so I started with those. 2D ran fine, I could visualize in paraview and color the surface by epsilon and see the movement of the free surface over time.
However, in the 3D case it seems as if all fields are constant throughout the entire simulation time. I see no changes when viewing in paraview as I did with the 2d case.
Am I doing something wrong? I run make, run the output executable (takes about 3 hours to simulate the 40 seconds), open the breakingDam3d.pvd file thats in the tmp/vtkData directory, and then apply in paraview and change the coloring to use epislon and color the surface. But the rectangle is just a solid color the entire time. This is the case for any of the fields, epsilon, physVelocity, physPressure, etc
Does anyone have any idea where I could be going wrong? thanks
January 29, 2025 at 8:27 pm #9812AdrianKeymasterWhat visualization mode / filter do you use in Paraview for the 3D case? Depending on the option the interior of the domain will be fully hidden by the boundaries by default, making it look as if nothing is changing. Did you try e.g. slicing the domain?
How did you execute the case? 3 hours seems quite slow.
January 29, 2025 at 8:56 pm #9813stoneprestonParticipantI will try slicing the domain tonight and see if that gets me anywhere. Regarding how I ran it, I simply downloaded openlb, changed into the dambreak2d directory, ran make, and ran the executable. Its possible no parallelization is happening and thats why its so slow. I dont have a GPU, but do have 8 cores available, is there a config setting I need to update?
January 29, 2025 at 9:07 pm #9814stoneprestonParticipantok slicing worked. Id like to be able to view the entire fluid domain, is there an easy way of accomplishing that (sorry for the basic questions, coming from openfoam and havent had to deal with occlusions like walls blocking the view of the fluid)
January 29, 2025 at 9:17 pm #9815AdrianKeymasterGood to hear!
One nice way is to use volume rendering in Paraview. Please note that this is not in any way OpenLB specific, we just export VTK that can then be post processed in e.g. Paraview the same way as an OpenFOAM case.
On the performance question: In that case you simulated without any parallelization (or even vectorization for the single process). For your hardware OpenMP will likely perform best but you can also use MPI. There is documentatiom on this on the user guide and also in the comments of the config.mk file where you can adjust the parallelization modes.
January 29, 2025 at 9:30 pm #9816stoneprestonParticipantOk perfect, yeah the volume based rendering seems to be what I want. Never used that option before. I will look into the openMP settings and see if that speeds things up. Thanks for your prompt replies
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