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I started looking for an OpenFOAM UI freeware a few months ago. FreeCAD with the CfdOF workbench seemed ideal. Coincidently, David Carter made a nice presentation at NARCON 2024 2 weeks ago on this very software.
I built up a simple test case of the Estes Fatboy design using the parametric Rocket workbench in FreeCAD plus a rear bulkhead to seal the fin can. Super easy.
From, there I built out a simulation with CfdOF. The seamless integration is fabulous!
There is a nice set of robust meshing and simulation options. I ran through about 20 mesh design iterations until I got something I liked. Meshing took about 1 minute on my Windows PC. 1-2 mm resolution on the rocket including boundary layers. The domain area is large enough such that blockage is less than 1%. Total cell count is about 2 million.
For the solver, I started out simple with steady, incompressible, turbulent RANS. I think this is a good model up to Mach 0.3. The solver took about 3 hours on 1 core. I couldn't get the MPI version working, but when I do, the solve time should drop to about 30 min on 8 cores. Here is the nice steady state convergence of forces. The drag results make sense.
Some flow images. The isosurface of total pressure = 0 shows the base wake as well as some flow loss off the square edges of the fins.
This is a game changer for hobbyists! Granted, I have a background in CFD, so the setup and analysis was very intuitive. Still, the workbenches in FreeCAD make it very easy. If you can CAD it, you can simulate it in minutes. Make design changes and everything in the workflow updates automatically. With some development of the CFD best practices and templates, I see this replacing Barrowman, RockSim, and OpenRocket for accurate aero analysis of any shape.
More to come in another post where I use this CFD model for center of pressure analysis.
I built up a simple test case of the Estes Fatboy design using the parametric Rocket workbench in FreeCAD plus a rear bulkhead to seal the fin can. Super easy.
From, there I built out a simulation with CfdOF. The seamless integration is fabulous!
There is a nice set of robust meshing and simulation options. I ran through about 20 mesh design iterations until I got something I liked. Meshing took about 1 minute on my Windows PC. 1-2 mm resolution on the rocket including boundary layers. The domain area is large enough such that blockage is less than 1%. Total cell count is about 2 million.
For the solver, I started out simple with steady, incompressible, turbulent RANS. I think this is a good model up to Mach 0.3. The solver took about 3 hours on 1 core. I couldn't get the MPI version working, but when I do, the solve time should drop to about 30 min on 8 cores. Here is the nice steady state convergence of forces. The drag results make sense.
Some flow images. The isosurface of total pressure = 0 shows the base wake as well as some flow loss off the square edges of the fins.
This is a game changer for hobbyists! Granted, I have a background in CFD, so the setup and analysis was very intuitive. Still, the workbenches in FreeCAD make it very easy. If you can CAD it, you can simulate it in minutes. Make design changes and everything in the workflow updates automatically. With some development of the CFD best practices and templates, I see this replacing Barrowman, RockSim, and OpenRocket for accurate aero analysis of any shape.
More to come in another post where I use this CFD model for center of pressure analysis.