Vortex Breakdown
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Respected Users,
I am doing a simulation of the vortex breakdown phenomena in an open cylinder(top) with rotating bottom wall. I am using water as the fluid and the bottom is rotated at Re=2600 as per the journal. The top is open to the atmosphere. At Re=2600 I am getting the exact replica of the vector plot but as the Reynolds number is increased I am not able to obtain the vortex breakdown phenomena. Breakdown was obtained in the journal at Re=3000. Following are the input parameters i am giving in fluent. Solver- Pressure based ,steady, relative Models- Laminar(all others off) Materials- water (from database) Cell zone condition- interior volume is made fluid and material is made water.The rotation axis origin is given as (0,0,0) and rotation axis direction as (0,0,1)(all other boxes are left unchecked) Boundary conditions- top is made pressure inlet bottom is made rotating by imparting angular velocity(by selecting moving,rotational,absolute) of .104667rad/s. radius is 15.23cm and height is 63.19cm side is made a no slip wall Reference values- compute from bottom is given and reference values are left as such, reference zone is selected as interior volume Solution methods- simple, least square cell based, second order, second order upwind Solution controls- under relaxation factors are retained as such(i.e pressure .3, body forces 1, density 1, momentum .7) Standard absolute initialization is given These are the various input parameters I am giving yet i am not able to obtain the breakdown phenomena. Any comments will be really valuable. Thanking you for your patience and help. P.S] I am also enclosing the velocity contour plot of my simulation at Re=2600 |
Thank you very much for your suggestions . Let me make a simulation with your suggestions and ill post the result.
Yes i think so. Consider the case of shock waves generated when the valve of a penstock pipe is closed. |
The transient mode you specified is also not yielding any vortex breakdown phenomenon. It is also giving the exact same result as i used to get with previous cases. Do you have any other alternatives for the problem.
Thank You |
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