I'm trying to determine the lift and drag coefficient of airfoil DAE-11 for laminar flow using Ansys Fluent laminar model.
RE = 260941.0492
Number of cells = 495700
Maximum mesh skewness = 0.84481
Minimum orthogonal quality = 0.11398
Maximum aspect ratio = 163.72
Wind speed = 4.075 m/s
I had tried playing around with SIMPLE, SIMPLEC and Coupled as well as skewness correction, courant number and relaxation factors. Lift coefficient, drag coefficient and residuals for 10AoA are included in the attachment. Both coefficients never stop fluctuating. Am I doing something wrong?
It might be worth mentioning that for 0-3 AoA, both lift and drag coefficients managed to settle down around 600-700 iterations with continuity residual of about 1e-3.
Hi Chi Hung Chong,
If all the setup in fluent are appropriate, I think this issue is mainly arised from the quality of grids. You probalely applied a high aspect ratio grids within the BL. However, large AOA will results in intense flow separation and high pressure gradent. This is really bad to the aspect ratio grids. You can check the contour of the unconverged result to get the position with abnormal values. Try to reduce the aspect ratio of grids as well as increase the quality of grids.
Good day. The Reynolds number is very small and the experiments are "capricious"; it never turns out perfectly. Maybe try the Menter flow model. Or use the resource http://airfoiltools.com. Matiychyk.
Hi. You can use XFLR5 software, because you're using a non-compressible model, so ANSYS is greater than you need. I recommend you to use XFLR5 you'll be fine to model that.
Hi Chi hung Chong
I think Shijie Qin's explanation probably can solve your problem of convergence. If you get any improvement kindly let me know.
- Badges
- Science topic