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Radhika January 16, 2007 20:04

What is the extrusion layer
 
Hi..

I am trying to simulate turblent flow inside a duct. I generated the mesh using Proam.

What exactly is the significance of the extrusion layer? is it just the surface mesh? Do I need to include it while specifying the boundary conditions.

I am novice with star CD. Please bear with me if it is an obvious answer..

Mac January 17, 2007 00:52

Re: What is the extrusion layer
 
Hi, Extrusion layer is the boundary layer that you generate for the wall (if required) depending on your application. Hope this helps - Mac.


9473247 January 17, 2007 18:08

Re: What is the extrusion layer
 
without extrusion layer your solution is really poor. It is not recommended to run a case without extrusion layer (except for fluent users :) )

ask your support office to explain you why with a picture.

Ionut Popescu February 1, 2007 22:51

Re: What is the extrusion layer
 
Hello !

The extrusion layer is one (or more) layer(s) of cells next to the wall. Let's say you have one layer... This layer has a thickness (which you specify) and this thickness is crucial for the y+ values in that region in a turbulent regime... This y+ value ideally should be between 30-100 (it works acceptable between 11-300) when you involve a high Re number k-e turbulence model. You have to be careful with this value especially when you compute heat transfer coefficients at the walls...

Radhika February 2, 2007 02:02

Re: What is the extrusion layer
 
Thanks !

I have another question.

I simulated the model with a default extrusion wall layer thickness of 1. The model converged. How do I check the values of y+. Can I check from the post processing files?


Ionut Popescu February 2, 2007 18:06

Re: What is the extrusion layer
 
Yes, you can. But you have to make sure that you checked this:in analysis output panel there is a tab which shows some variables to be either posted or printed. Among those there is y+ values.., You have to check the "post" button for that value and run you simulation for 1 more iteration. The results pst file will contain the y+ value... You get it with the command: getw,yplu



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