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-   -   Poor convergence with high streamwise loss multipler (http://www.cfd-online.com/Forums/cfx/92681-poor-convergence-high-streamwise-loss-multipler.html)

mullenc525 September 21, 2011 16:38

Poor convergence with high streamwise loss multipler
 
Hi,
I am doing flow distribution analysis where I am using a porous media to simulate many small channels within a heat exchanger. I want to force the flow to be parallel within the porous media, which necessitates a high streamwise coefficient multiplier. The difficulty I am having is when I make the multiplier much bigger than 10, the solution convergence becomes highly oscillatory and I can't get good convergence.
Any ideas?

ghorrocks September 21, 2011 19:20

I suspect the tips here will be relevant:

http://www.cfd-online.com/Wiki/Ansys...gence_criteria

dvanb September 23, 2011 16:54

Apologies if I am not remembering this correctly, it's been a couple years since I did this kind of simulation, but:

you are saying you need a large stream-wise loss coefficient. I would think that in fact the directions _normal_ to the stream should have the very high loss coefficients to suppress crossflow. Your stream-wise coefficient should be whatever you need to simulate the expected pressure drop through the HEX for a given flow rate.


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