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-   -   Taylor Couette Setup and Boundary Conditions (http://www.cfd-online.com/Forums/openfoam-pre-processing/122568-taylor-couette-setup-boundary-conditions.html)

DaSh August 22, 2013 06:53

Taylor Couette Setup and Boundary Conditions
 
Hello Fellow-FOAMers,

I am currently working on a setup for LES of a Taylor Couette flow. To test my setup and mesh, I start out with a laminar simulation (turbulence properties set to laminar).

I want to create both laminar couette flow and laminar taylor vortex flow. I use a setup with eta = 0.5, so I have a critical Reynoldsnumber of about 78.

The problem is, that I can see vortices on both ends of the cylinder for Reynolds = 50 (smaller than Re_crit) by visualising the y-compinents of velocitiy, like this:

http://s1.directupload.net/images/130821/oynbwlsv.png

Of course for laminar couette flow, there should be no velocities in y-direction.

I use icoFoam as laminar solver. Boundary conditions for p are all zeroGradient for innerWall outerWall and upper and lower end. For U all are fixedValue ( 0 0 0 ), just innerWall is

rotatingWallVelocity
origing (0 0 0)
axis (0 1 0)
omega 0.004; (rad/s, which leads to 0.002 m/s and Re = 50; viscosity 2e-5)


Has anybody got an idea how to improve the setup, or why i get these vortices at low Re? Maybe cyclic BC at top and bottom are necessary?

I am grateful for any kind of help!

Regards,
DaSh

DaSh August 22, 2013 06:55

I have tried cyclic BC and symmetryPlane BC, which produces even worse results concerning velocity in y-direction.

Has somebody got an idea, why I see y-Velocity (v) in laminar case with Re smaller Re_crit?

Thanks in advance!

Danesh


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