Coefficient of pressure (Cp) curve unstable/unsteady
 

I am currently working on a CFD analysis of 2D and 3D airfoils. I am using Pointwise to mesh the geometry and using ICEM to convert the .cas file to .msh (to be used on an in house code). The code is a RANS solver and I am using k-omega SST with the y+ value being less than 1.

I have been running unidimensional and compressible simulations but for some reason when I plot the Cp curve it is very unsteady (choppy or erratic). I have included the screenshot of the issue. I am not sure why this is happening.

I have carried out a grid independence study and as you make the grid fine, the unsteady behaviour is even more profound. I am using an o-grid for the mesh and it is normally extruded from the surface.

I have tried different boundary conditions but nothing seems to be working. I have discussed the issue with my supervisor and he has recommend that it is something to do with 'spatial resolution'. He also said that the this erratic behaviour could lead to early separation and give invalid results.

I am new to CFD online so I apologise if I have not adhered to some pre determined norm. Any help would be greatly appreciated. Thank you.


https://imgur.com/a/coIxnUi