Resolving unexpected flow near distributed resistance regions

Mar 3, 2012


The resultant velocity field in some Autodesk® Simulation CFD 2012 simulations in which flow deflects off of or passes around a resistance material is different from results predicted in earlier versions of CFdesign.



A new smoothing algorithm was introduced into CFdesign 2011 that improves velocity results near resistance materials. 

This algorithm assumes that the flow passes through the resistance, instead of deflecting off of it, and smooths the flow vectors using the upstream velocities. 

These upstream velocities provide the direction for the downstream nodes.  If the upstream nodes deflect the flow, then all downstream velocities will be deflected creating an odd looking vector field.

To resolve this issue, add the following flag to the cfdesign_flags.txt file:

DRSmoothing -2

This disables the smoothing algorithm, and produces results consistent with earlier versions of CFdesign.




Simulation CFD