[Gmsh] How to make a hole in a volume?

[Hengjin Liu]

Hello, 
 
I am trying to create a simple block with an internal hole (a smaller block) using GUI. 
 
I select the external boundary surfaces to create the volume and then select the internal surfaces as the hole following the message in the GUI windows. However, when I am trying to generate the volume mesh, I get an error message saying that an edge 6 is multiple time in surface mesh.
 
I attached the .geo file with this e-mail. Should the internal hole be explicitly defined as a volume? or the characteristic length I choose is not good for the model.    
 
Is there a way to visualize the volume mesh to make sure that there is no elements generated inside the hole?
 
Thanks in advance!
 
henry
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE!
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20060601/5d173410/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: blockwithhole.geo
Type: application/octet-stream
Size: 2041 bytes
Desc: not available
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20060601/5d173410/attachment.geo>