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Old   March 10, 2011, 05:55
Default Transfer of velocity profile!!
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Hi everyone,


I have used velocity profile at the inlet of my CFD-Post of my reference case which uses pressure as a inlet boundary condition as a boundary condition for the setup of another model so that i wil get the same amount of mass flow rate. But it seems that it is varying. So can anyone tell me if i have to also change the boundary conditions at the outlet according to that??


Hope somewhere answers me..and atleast some of them are not in holidays:P

Thnks,

Krishna
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Old   March 10, 2011, 07:26
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Glenn Horrocks
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No holidays here in Australia. But I do not understand your question. Can you explain again?
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Old   March 11, 2011, 05:24
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The thing that we are trying to do is Assess the cooling efficiency of a parralel + cross flow heat exchanger which uses the principle of impingement cooling for differeent changes in the design of the 3D-Model.

I am attaching you a small picture of the Velocity profile thing at the inlet.



So what we are doing is using the velocity profile at the inlet of the reference case and transferring it as an inlet boundary condition for the other designs so that we get the same amount of mass flow rate or amount of air and thta we can compare the temperature distribution in the SOlid and asses s the cooling efficiency.

And since it did not work we also tried to give teh target Bulk mass flow as an outlet bounadry condition. But even then it doesnt work? IT converges but the MAss distribution in the solution monitor is uneven. And also the pressure drop between the inlet and outlet goes to zero once and fluctuates a lot in the beginning

I hope you understood now
So any suggestiong?
Attached Images
File Type: jpg Velocity profile for reference case@Inlet.jpg (38.7 KB, 7 views)
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Old   March 11, 2011, 05:45
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If you use a velocity inlet this should work and maintain your mass flow rate.

Also if you specify a mass flow rate that is what you should get - if you did not get it then your model is not converged. Might need to improve mesh quality or larger timesteps (if steady state).
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