Hi there,
I'm working 2D axisymmetrical pipe groove (CFD) model with constant wall temperature. During the hybrid initialization, I have a non-positive element error along with a floating point exception. I believe I'm missing something. Any suggestions would be really helpful?
Thank you
I would suggest using Hexa mesh instead of tetra.
https://www.youtube.com/watch?v=6YLeqnFnnsM
If you want to go with tetra mesh please redo the meshing starting from line mesh . Please check the mesh after importing to fluent for negative elements.
Srinivas Rao Ahmed Hasan Many thanks for the suggestions. I think I figured out the reason for the error.
Above, mesh details:
Average Mesh quality : 0.91
Average orthogonality: 0.92
Average Skewness : 0.1
The mesh quality is acceptable, and the problem lies within the geometry. since this is an axi-symmetric 2D model. The basic idea of geometry must stay in the first quadrant, which is the +XY plane region. So, that model rotates around the axis. From the 2 pictures attached, the centered axis geometry was found to be in all four quadrants, causing the solver to confuse and throw errors like negative volume and floating point exception.
Two ways to fix the error:
1. Redesign the geometry and place it above the positive x and y axis.
2. In Fluent, use the transform button to change the axis, and in Spaceclaim, add origin to change the axis .
Of course these are all suggestions:
Dont use tetra mesh for CFD.. Mesh looks fine at the surfaces but not in the internal regions.
Use Auto method or the Multizone method.
It looks like your boundary layer inflation is not tall enough. Use more layers. leave the growth rate as 1.2
Also it looks like your mesh growth rate is large. I would suggest using 1.025.
Hi Semih M. Ölçmen Thanks for your suggestion. I will definitely improve the mesh with these settings.
i actually meant to say.. dont use hexa mesh.. i could not go back and correct it.. sorry about that..
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