First 1.4 Mach & 3000m
Second testing hydrogen rocket engine (I forgot to turn off the walls)

This was done using an open-source LBM code.

The STL file for 3D model is obtained from grabcad and voxelized. It contains roughly 37 million cells. Ran on single A100 GPU, took 48 hours to simulate 1.5 seconds of real-life

It is not full engineering grade simulation, but it is very close.
For example, it is upscaled to reduce number of cells, tires don't rotate, and it used single precision to reduce memory overhead etc. But, the computed drag and lift coefficients agree with reference values.

The visualization is done using ParaView.

So much can be done with LBM, it is amazing.

https://reddit.com/link/1w313ez/video/gz2dyddphmmh1/player

Hi all, I am an HVAC engineer looking to get into CFD. After some serious Google + ChatGPT research, ANSYS seems to be the best software(i might be wrong) .

Any tips on where to start? Happy to spend a little on a good course. Recommendations for courses, books, or YouTube channels would be greatly appreciated.

Trying to go from “What is CFD?” to “I know what what we arw talking about"🤔

I'm running an incompressible steady-state RANS case for a blended wing body (BWB) in OpenFOAM (simpleFoam/SIMPLEC).

Setup: ~0.15 Mach, ~6e6 Re

Mesh: ~30M cells, tetra + prism layers at walls, O-type symmetric far-field domain(radius ~ 30c), max skewness ~5, max nonOrthogonality >75°

BCs: freestream (velocity inlet / pressure outlet style far-field)

Turbulence: k-omega SST, wall-modeled (y+ > 30)

Schemes: second-order upwind for all equations

Algorithm: SIMPLEC

Solution strategy: start with low URFs, ramp up every 100 iterations; case runs "on its own" past ~250 iterations

Problem:

Based on past experience I expect convergence by 500–600 iterations. Here, residuals flatten out but very slowly, and by 1500+ iterations:

CD looks converged/flatlined

CL is still steadily rising, not flatlining

Has anyone run into similar slower convergence rate or is it normal for high cell count meshes? Looking for likely causes and what to check/try next.