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haconk July 31, 2009 08:18

Total Mesh Displacement X not available in v12.0??

I had specified mesh displacement like
x0 = x - Total Mesh Displacement X
in an expression in v11.0

Now trying to do the same in v12.0, it gives me an error saying the variable is unavailable. Looking at the documentation, the variable is "Total Mesh Displacement" but without the X or Y. Is this right and how would I calculate my x0 from now on?

Many thanks

ghorrocks August 2, 2009 00:16


You have not specified how you want to deal with the variable. Maybe areaAve(Total Mesh Displacement X)@region?

Glenn Horrocks

haconk August 3, 2009 08:09

I wasn't using any of those functions (like areaAve) in v11.0.

Basically, I'm setting a moving mesh. So, I defined the expressions (simplified):
X0 = x - Total Mesh Displacement X //original node locations
X New = X0*cos(angle) - Y0*sin(angle) //new location
x Motion = X New - X0 //relative movement

And then set in the boundary conditions "specified displacement" X = x Motion.

This runs fine in v11.0. But in v12.0 it doesn't. Don't understand why I should use weighted area average, I was under the impression, X0 is calculated for each node separately. What am I missing here?

ghorrocks August 3, 2009 19:11


OK, I see now. I was not aware of any changes to the handling of anything here in V12. There are a number of ways of specifying the mesh motion (specified displacement, specified location etc) so you might have to try a few of them to find one which works. It might also be worthwhile talking to support to find out what has changed here.

Glenn Horrocks

haconk August 4, 2009 03:44

Thanks, Glenn. Support has ignored all my requests so far. Probably because I am on an academic license.

I'm going back to 11.0 which is quite frustrating as I set up a whole bunch of models in 12.0 WB and none of them can be used in v11.0. Just opening DM with a 12.0 model throws up lots of exceptions...

ckleanth August 4, 2009 06:15

could raise a support request in your behalf if you want - pm me if you want me to go forward (will need a simple case in v11 and v12 to email to ansys)

Sveink October 1, 2009 09:39

I have the excact same problem. A bit different expressions, but same error message and the v11. to v12. problematique.

Found any solutions?


zeitistgeld December 10, 2009 09:47

I do have the same problem. How so? Does anybody know about it? Is it a bug?

Tristan December 10, 2009 16:18

I switched over to the 'Specified Location' option for describing the mesh motion since I couldn't make 'Specified Displacement' work properly with CEL and the Total Mesh Displacement variable in CFX 12.

Minnick July 9, 2010 09:12

Has anyone resolved this issue? I have the same problem. Specifying moving object displacement OR position as a function of time is often very difficult if you can't reference where the object was before the displacement started.

CFX is definitely aware of what the original position of a displaced point was because it uses it when it calculates new position by setting "Specified Displacement". So, there must be a variable for this. Anyone know what it is?

bramdiff March 9, 2011 06:58


I have recently had the same problem using v12.0...

I spoke to ansys support and they said that 'total mesh displacement' wasnt available in this version- but this was rectified in v12.1 and v13.



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