Problem With Deforming Mesh
 

Hallo everybody
I've a problem with deforming mesh I've ever seen,
There is a perfect hex mesh made with ICEM, and a simply moving wall.
Happens that the mesh when the simulation go on, become less parallel
as the time go forward.
To better explain the problem there is an animation of the mesh and a particular of the distorsion of the mesh after a lot of iteration.
You can find files on the link below.
Why the mesh lose parallelism during simulation ?

https://www.dropbox.com/sh/zz5x4soel...Z1y-gDoda?dl=0

I am not able to go into drop box, but what you describe can be done easily.

You need to write a CEL script to update mesh deformations precisely. Instead of moving just the boundary, create a subdomain and deform the subdomain.

Your deformation will be 1 at the boundary, 0 at the fixed wall, and linear function in between.

You should be able to search in this forum for more details on this approach.

Thankyou Singer,
you are rigth and I will try your suggestion, now I've bypassed the
problem adding a remesh command into CFX, but I don't understand
why the top geometry that move in the same way mantain perfect parallelism between elements, and the middle geometry deform in such way the elements.
I don't see any difference.... does anyone know the reason?

Sorry Singer,
I've looked for your suggestion in this forum and I haven't found anything,
plese can you expalin little bit when you say to drive precisely the mesh with cel scrip ? Pheraps you mean junction box routine ?

Specify your subdomain and expressions. For example the below is a subdomain that "squashes up in the Global X direction. x2 is the stationary wall location (it will move at 0*movefront) and x1 is the moving wall side (it will move at 1*movefront). In between meshes will get linearly "squashed" (zero to one*movefront based on X location) in between. Travel(t) is a tabular function of my travel versus time (you can make these directly in Pre).

EXPRESSIONS:
movefront = (Travel(t)-Travel(tstart))*min(1,max(0, (x2-x)/(x2-x1)))
tstart = .0 [s]
x1 = minVal(xGlobal)@Sub_Front
x2 = maxVal(xGlobal)@Sub_Front
END

SUBDOMAIN: Sub_Front
Coord Frame = Coord 0
Location = FRONT_AIR
MESH MOTION:
Option = Specified Displacement
DISPLACEMENT:
Displacement X Component = movefront
Displacement Y Component = 0 [m]
Displacement Z Component = 0 [m]
Option = Cartesian Components
END
END
END

Thankyou singer,
I'hadn't seen the meaning of your suggestion, now I've done and
everything work perfect thankyou verymuch:):):):):):):)

Now if you are so kind, I'd ask any more thing: I've the results
of a transient analisys for a period of 10sec.
I'd like to calculate the mechanical work of the mechanism during one
cycle. I've the monitor out file of the pressure and the monitor of the
positions of the moving walls. With excel is easy to combine the results
and obtain the work / cycle, but it'snt usefull for my final goal.

I whant to do a geometric optimizaton of the model and I've made
a series of design points. I'd like to know if there is a way to interpolate the
results of a transient analisys in order to obtain a unique value to be used for
the goal of an optimizaton study.