[shovaliye2]

I am simulating flow around 2D hydrofoil in ansys fluent.

I am doing this for various angle of attacks between 0 to 20 degrees. the results are ok until 12 degree but after that residuals and lift and drag coefficients plots became oscillating. how can I solve this problem?

for more information:

the model is k-epsilon (realizable and standard wall functions). scheme is coupled and gradient option is green-gauss cell based. pressure, momentum, turbulent kinetic energy and turbulent dissipation rate are chosen second order.

[vinerm]

Beyond 12 degree AoA, it is quite possible that the boundary layer is separating. If that is the case, then you cannot use standard wall function; it is not applicable for even slightly separating flows. So, you have to refine the mesh to maintain below 5 and use either EWT or Menter-Lechner.

[shovaliye2]

Originally Posted by vinerm

Beyond 12 degree AoA, it is quite possible that the boundary layer is separating. If that is the case, then you cannot use standard wall function; it is not applicable for even slightly separating flows. So, you have to refine the mesh to maintain below 5 and use either EWT or Menter-Lechner.

Is there any way in ansys fluent to know what is the magnitude of ?

[vinerm]

Wall Yplus is available under Turbulence category. You can plot its contours or xy-plot on the wall of the hydrofoil.