[Foxbor]

Well, I wanted to ask some questions related to a problem I am having in ANSYS:


I have been trying to perform the simulation of a Flow around a 2D Circular Cylinder (classical to get the von-Karman street) at 500 000 Reynolds, U-RANS, SST k-w model. I did this simulation in CFX (3D with one cell in z) and FLUENT (2D), with same mesh parameters (y+<1), same timestep and with the highest-order schemes for both softwares (Both QUICK even with Turbulence, Second Order Backward Euler, etc). The results: Cd (Drag coeff) that varies 20% between softwares, and an amplitude of Cf (Lift Coeff) that almost varies 3 times (!!!). I tried a lot of things, changing schemes, mesh size, etc. but the difference on results still persists. I have thought maybe the SST formulations on both softwares might be somehow different, or maybe the cell/node centered method of both softwares might be affecting, but what was interesting was the next thing I just found in CFX:


The variable Wall Distance, that should represent the distance of a point to the nearest wall is not the right one (geometrically speaking). The first image displays that to the limit of my domain I have a distance of 25 m from the wall, while my domain has a Radius of 15 m (Cylinder of 0.5 m Radius). Second image shows that even near to my wall, the Relationship between the Wall Distance Vs Y (Starting from the cylinder's wall) is not even Linear. I have read the documentation (3rd image) and I dont understand the objective of this kind of "Wall Distance" calculation.
Having an incorrect "Wall Distance" actually can be the answer to my problem in CFX, since it can strongly affect the Turbulence Model near the wall in the calculation in the Blending Function, getting different Pressures and Wall Shear Stresses, which might result in having this different results with FLUENT.


From here, my questions are the next:
1) How should my Pseudo-2D simulation in CFX be so the Wall Distance would be calculated properly? What could be the problem?
2) Why does CFX uses such a strange (for me) algorithm to calculate the Wall Distance and not just use the Geometrical Distance?
3) Is there a way to Override the calculation of this variable and, instead, force the Wall Distance = Geometrical Distance through the Command Editor?


PD: My Domain has Two Sub-Domains for meshing purposes, connected by an Interface GGI.