Polyhedral Mesh and CFX!!!

Far · February 24, 2012, 05:27

Dear All

It has been discussed on CFX forum already that the CFX is vertex centred solver and constructs the cell around the vertex. Thereby making the control volumes of different shapes (not similar to original mesh as Fluent Does) and rougly can classified as polyhedrals. My question is that if CFX can handle or by dafult creates the polyhedral control volume, then why CFX cannot read the polyhedral mesh?

ghorrocks · February 24, 2012, 06:10

Because the only element topologies which it can construct the polygons from are tet, pyramid, wedge and hexes. For elements more complex than this it is not easy to contruct the control volumes around the nodes.

Far · February 24, 2012, 06:50

same goes for hanging nodes?

(Following are some observations I have made over the years for both solvers not directly related this post)

CFX users shall not be benefited from the new meshing technology developed (still developing) in ANSYS meshing such as cut cell and cut tet methods in version 13 and 14. On the other hand Fluent can handle them easily.

This is the clear reason why ANSYS kept both solvers in CFD suit and investing time and money in developing them further. And they have also improved the Fluent convergence speed considerably and it is now similar to CFX.

Both are best in their respective areas.

ghorrocks · February 25, 2012, 05:47

Yes, same goes for hanging nodes. CFX's normal control volume needs to be modified to handle it and that has not been done yet.

February 24, 2012, 05:27	Polyhedral Mesh and CFX!!!	#1
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	Dear All It has been discussed on CFX forum already that the CFX is vertex centred solver and constructs the cell around the vertex. Thereby making the control volumes of different shapes (not similar to original mesh as Fluent Does) and rougly can classified as polyhedrals. My question is that if CFX can handle or by dafult creates the polyhedral control volume, then why CFX cannot read the polyhedral mesh?

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February 24, 2012, 06:10		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Because the only element topologies which it can construct the polygons from are tet, pyramid, wedge and hexes. For elements more complex than this it is not easy to contruct the control volumes around the nodes.

February 24, 2012, 06:50		#3
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	same goes for hanging nodes? (Following are some observations I have made over the years for both solvers not directly related this post) CFX users shall not be benefited from the new meshing technology developed (still developing) in ANSYS meshing such as cut cell and cut tet methods in version 13 and 14. On the other hand Fluent can handle them easily. This is the clear reason why ANSYS kept both solvers in CFD suit and investing time and money in developing them further. And they have also improved the Fluent convergence speed considerably and it is now similar to CFX. Both are best in their respective areas.

February 25, 2012, 05:47		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Yes, same goes for hanging nodes. CFX's normal control volume needs to be modified to handle it and that has not been done yet.