CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   GGI interface and meshing (

Vincent June 2, 2003 03:50

GGI interface and meshing
Hi everybody, I try to simulate the heat transfer in the roof of a road tunnel during a fire. Because of this, I use different imported domains with different kind of mesh. My problem is that on an interface between a cubic mesh and an irregular mesh, I have differences of velocity and temperature fields, specially where I have important gradient. I think the problem comes from the differences between the size of the elements of each part and I like to know how elements have to be at an interface to keep a good continuity of fields. Thanks.

vlado June 2, 2003 05:01

Re: GGI interface and meshing
if you have a big gradients and if you want to get good results you ned to have very dense nodes especialy in boundary layer. So the first step is to increase the node density in both meshes on the contatct surfaces.

Danie June 2, 2003 12:32

Re: GGI interface and meshing
Hi Vincent, It would be good if you have similar edge length across the interface. Moreover, having a inflation on the unstructured side with prism heights corresponding to that of structured side would improve the gradient resolution. An important note to make is GGI captures accurately gradients which are across GGI, but gradients along interface are poorly captured. You may have to redo the interface accordingly.

All the best, Danie

Vincent June 4, 2003 03:29

Re: GGI interface and meshing
Thanks, If it could help someone, there is a patch on the cfxcommunity site. This patch resolves the problems that you could meet with a flow parallel to the interface. It is strongly recommended to install it if you use GGI interface with CFX 5.5.1.

All times are GMT -4. The time now is 01:08.