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-   -   Velocity overprediction (http://www.cfd-online.com/Forums/cd-adapco/53363-velocity-overprediction.html)

Julie Polyakh June 22, 2003 06:06

Velocity overprediction
 
Hi!

What may cause the flow velocity overprediction of 30% in its maximum point? Problems begin already at the secondary inlet boundary : the U-velocity value after computation is 55% higher than the initial one defined in the BC. The flow swich for BC is 'Fixed Mass'.

Thanks, Julie

cjtune June 22, 2003 23:57

Re: Velocity overprediction
 
You should use the 'Fixed Velocity' switch for your second inlet as opposed to 'Fixed Mass'. STAR-CD adjusts the inlet velocity to match the mass flow that you want fixed by (roe)*A*|U|.

Julie Polyakh June 24, 2003 04:54

Re: Velocity overprediction
 
Hi,

The problem is that I need mass flow to be fixed... There was no overprediction with more coarse grid even with 'Fixed Mass' option.

Regards,

Julie


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