Some question about the advection scheme in DES
 

Dear everyone,
With the help of CFX 14.0, I have done a simulation about Landing gears using High resolution discretization scheme in DES form. But existence of the 2 variables named "Blending function for DES model" and "Velocity .beta" in CFD-Post really confuses me . According to the CFX Theory's Guide,the value of the former varaible is 1 denotes the user-defined scheme(e.t.c HRS) while 0 denotes Central-difference scheme. And as for HRS,the value of the "Velocity .beta" is 1 denotes the CDS while 0 denotes Upwind-difference scheme. But how can we explain the two images below?:confused:
I have attached the images of "Blending function for DES model" and the "Velocity .beta". So the question is what the real discretization scheme used in "LES" region of DES? A full CDS can contribute to the "LES region" (the blue region) referring to figure 1 ,while a HRS,namely both UPS and CDS can be found in the "LES region" according to figure 2.


Thanks
TAKEDA dql

First of all, your software is very old. There is lots of updates and fixes in the current software so you should consider updating to the current version (V18.2).

The Blending function for DES variable defines the regions where the RANS model or the DES model is used. It does more than just change the advection scheme.

Dear ghorrocks,
Thanks for your prompt reply.
The grid for this simulation is about 12million, and only the HPC can help. Unfortunately, the current software in HPC is CFX 14.0, which I can not change. And I read the literature about DES-SST(Strelets 2001), so what I exactly concern is the real advection scheme used in the "LES" region for CFX, the CDS, or both CDS and UPS?

Best regards
TAKEDA dql

You should read the documentation for details, but I think it uses the central differencing scheme in the LES region.