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[ANSYS Meshing] Fluent crashing with dynamic mesh

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Old   September 16, 2018, 00:46
Default Fluent crashing with dynamic mesh
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Hello all,

I'm trying to simulate a tilted metal plate being dropped into a tank of water. The solution method is realizable k-epsilon with scalable wall function. I am using a dynamic mesh and the 6DOF module. The version of ANSYS I'm running is v17.0 and so I have to utilize a compiled UDF to specify the 6DOF inertial properties.

The solver seems to run fine until the mesh becomes stretched. The residuals suddenly diverge very, very rapidly. In fact, it's in the matter of a single timestep (of dt = 0.0001 sec).

My mesh is uniformly "fine" with an inflation later of 3 around the plate. This is the initial mesh (with VOF isosurface):



And this is the last mesh before the solver fails:



To me, this does not look like I've done a good job setting up the remeshing. Properties of my dynamic mesh:




At this point, when I try to run the solver/hit "calculate", Fluent simply crashes on me. Could it be that my cell skewness is dangerously close to 1.0? If so, how do I go about fixing that? If not, what might it be?

Thanks!

G
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Old   September 26, 2018, 01:52
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For anyone who has a similar problem, I was able to get this to run by lowering the Spring Constant Factor from 0.4 to 0.1. I also switched the smoothing to All elements as opposed to Tet in Tet Zones.

I also used the TUI to repair the mesh. Previous mesh quality:

Code:
Mesh Quality:

Minimum Orthogonal Quality =  6.42138e-03
(Orthogonal Quality ranges from 0 to 1, where values close to 0 correspond to low quality.)
Warning: minimum Orthogonal Quality below 0.01.

Maximum Ortho Skew =  8.72385e-01
(Ortho Skew ranges from 0 to 1, where values close to 1 correspond to low quality.)

Maximum Aspect Ratio =  3.06761e+01

Fluent can try to improve the mesh quality via the TUI command
/mesh/repair-improve/improve-quality
And this is the new mesh quality:

Code:
Mesh Quality:

Minimum Orthogonal Quality =  2.02785e-01
(Orthogonal Quality ranges from 0 to 1, where values close to 0 correspond to low quality.)

Maximum Ortho Skew =  7.14713e-01
(Ortho Skew ranges from 0 to 1, where values close to 1 correspond to low quality.)

Maximum Aspect Ratio =  1.56815e+01
In so doing, the maximum cell skewness lowered to ~0.797, and I used this as the new maximum cell skewness value for the remeshing scheme.
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