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Unbelievably high velocity magnitudes in film cooling - HELP!

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Old   June 1, 2009, 22:43
Default Unbelievably high velocity magnitudes in film cooling - HELP!
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I am trying to do 3D modeling of a rectangular plate with film cooling holes. The upper side of the plate is the flow area and the lower side is the cooling plenum. My gas inlet is at 173 m/s and coolant inlet is at 39 m/s. The velocity magnitude at the entrance of the film cooling holes should be around 100 m/s.
I created a point monitor to monitor the velocity value near the entrance of the film cooling holes. The monitor starts at 2400 m/s and goes down till 1000 m/s during which time my residuals are all going down smoothly. After about 100 iterations, the convergence residuals suddenly spike up by around 2 orders of magnitude and my velocity magnitude value starts going up and keeps rising back to 2400 m/s. Is this a problem caused due to poor meshing? Is there any other reason for this behavior?
I am using the k-omega turbulence model, steady solver, pressure based. I have tried converging for a laminar case and moving to turbulent, reducing the URF's and solving flow equations first and then moving on to turbulent. Nothing works.


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