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Calculation of Vorticity

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Old   July 8, 2010, 18:49
Default Calculation of Vorticity
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Antonio
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Hello,

I am using fortran for simulating the fluid flow not based on Navier Stokes but on lattice Boltzmann method!

I would like to evaluate the vorticity, given the velocity vectors.

The vorticity is, for the x direction, equal to:

_x=(u_z(x,y+1,z)-u_z(x,y,z))-(u_z(x,y,z+1)-u_z(x,y,z))
since u/x=lim(x-->0)[u(x+x)-u(x)]/x hence I have to take the value of the next lattice minus the value at the lattice divided by one, which is the x.

Apparently tihs doesn't give the expected result in terms of vorticity. I was reading something here: http://folk.uio.no/jks/matpiv/html/node31.html but I'm not sure and I wanted the opinions of CFD, since in CFD softwares the vorticity is evaluated automatically.

Regards

Antonio
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Old   July 12, 2010, 04:10
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Rami Ben-Zvi
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The vorticity definition (in tensor notation) is wik = (ui,k-uk,i)/2, while your expression is wx=ux,y-uz,z - which is wrong.
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