[diwakarsingh64]

hello everyone,

I am simulating a simple NACA 23012 3d wing at an angle of attack 8 deg...using simpleFoam. Reynolds number of around .25 million. Cl and Cd values turning out to be fine. Its the Cp plot wiggles around the leading edge that is the problem. Could it be over/under resolution of the mesh. Or is it owing to the geometry curve created by the icem when coordinates are imported. I have attached an image with it to show where exactly are wiggles existing.
kindest regards

[tas38]

What is the grid resolution around the wing and how did you extract the pressure curve?

[diwakarsingh64]

hello tas

y+ around the wing is of 1 (prism) and for pressure curve in tecplot surface slice on wing and then x-y plot in a new tiled frame.
kind regards
D singh

[diwakarsingh64]

sorry another question, If one puts first cell outside the buffer layer not resolving the subviscous layer, does that result in wiggles in cp ?! if yes then why so?
kind regards

[tas38]

Your y+ value is small such that you are actually resolving the viscous sublayer. If you are using (standard) wall functions, you should reduce the grid density to get a value around 30. If you are using enhanced wall functions the value is fine. Also, what is the grid density in the streamwise direction (approximate number of grid points along the upper and lower surfaces of the wing) and the ratio of grid sizes normal to the wing?

[diwakarsingh64]

Thanks for your reply. In case if there is anything wrong with the grid sizing or the resolution I wonder why the wigles are present only on the upper surface. And sorry I didnt understand what you meant when u said that I am resolving sub-viscous layer. That is the reason why I chose yplus to be 1 since I want to resolve boundary layer completely. And how would using wall fuction(thereby increasing the yplus to 30 or 60 depending upon the model) will eliminate the wiggles. Sorry if I am missing some physics in here. Would be grateful to learn it.
kindest regards

[tas38]

Originally Posted by diwakarsingh64

Thanks for your reply. In case if there is anything wrong with the grid sizing or the resolution I wonder why the wigles are present only on the upper surface. And sorry I didnt understand what you meant when u said that I am resolving sub-viscous layer. That is the reason why I chose yplus to be 1 since I want to resolve boundary layer completely. And how would using wall fuction(thereby increasing the yplus to 30 or 60 depending upon the model) will eliminate the wiggles. Sorry if I am missing some physics in here. Would be grateful to learn it.
kindest regards

I see wiggles on both the upper and lower (less pronounced) surfaces. Could you post a picture of the zoomed-in picture of the wing and grid near the leading edge? Also, is your solution converged and by what criteria?