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Difference in Visualization of q criterion in tetra and hexa mesh

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Old   April 23, 2018, 00:30
Default Difference in Visualization of q criterion in tetra and hexa mesh
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raunak jung pandey
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I am carrying out a simulation of external flow using SST model. I carried out simulation using both tetra and hexa mesh. The y+ =1 on the external flow and node number is 2.9 million.

Simulations are carried out with same boundary conditions. But tetra mesh shows different results near the boundary layer which is not present in hexa mesh.

If some one has experience carrying out such simulation please suggest what is happening ?

Thank you

this is results with tetra mesh



this is results with hexa mesh
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Old   April 24, 2018, 18:43
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Lucky Tran
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Are you even comparing apples to apple?

The top plot is presumably the isosurface of Q=0? colored by velocity magnitude?

Then why is the bottom plot of "Velocity.InvariantQ" having units 1/s^2 and having magnitudes (10^12) that do not look like velocities? And the flow is going along a different axis.

Sorry but it seems there is a lot more going on here.
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Old   April 24, 2018, 21:37
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Thank you for replying.

The top plot is not iso surface at Q=0. both the iso surfaces have been drawn at Q= 500,000 s-2. In the top plot the isosurface exists in higher Q also.

The bottom isosurface is not colored by velocity magnitude hence. Please neglect the axis right now.

The boundary conditions remains same for both simulations. The difference is only the mesh used. Upper being tetra and latter is hexa.

Check in this figure. The Q originating from the device to the external domain is different.

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