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February 16, 2023, 16:00 |
CL is so high
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#1 |
New Member
Eduardo Ireta
Join Date: Feb 2023
Posts: 1
Rep Power: 0 |
Hi, i new in OpenFoam, I try to make a simulation to get the cl of a plane but i have 3 problems:
1.-The principal problem is for the cl is so high, I'm trying to make a comparison with several CFD programs (fluent, xflr5, OpenFoam) and the cl is like to 0.28, but in OpenFoam i got 3.3. I donīt know what is the problem, i change several values like Aref, Umag, etc.. 2.-The simulation never converges, I end up truncating the simulation at time 500 or 1000 for get the values. 3.-When I visualize the results in openfoam and the end of the control volume the speed rises very quickly until it reaches 30 m/s. If I increase the size of the control volume in that direction, the speed continues to increase. I would like to know what my faults are so I can learn more about openfoam. This is the directory link https://drive.google.com/drive/folde...jj?usp=sharing |
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February 17, 2023, 14:42 |
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#2 |
Senior Member
Join Date: Apr 2020
Location: UK
Posts: 736
Rep Power: 14 |
Point 1 (bad CL prediction) is probably lined to / the result of point 2 (poor convergence), as is 3 (unphysicak results).
Taking a brief look at your model - forgive me for saying, but your mesh is awful. Your mesh refinement zone seems to have missed your geometry, and the resolution at the outlet is probably too coarse - see the attached. My advice is to start by getting a better mesh. If the case still falls then we'll need to look at the BC's ... I didn't open them. But start with the mesh. Good luck! |
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Tags |
aerodynamic, cfd, coefficient of lift, converge cfd, openfoam |
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