patch: nothing happened..!

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 October 25, 2007, 04:59 patch: nothing happened..! #1 sheila Guest   Posts: n/a Hi, I have a duct geometry. I want to patch pressure at the inlet and outlet of the duct. I marked the cells using adapt region and used the solve -> initialize -> patch. I ran Fluent and after it converged I plot the pressure along the duct. It turned out that nothing happened. The pressure distribution remained the same. Can you help me explain this problem. Thank you

 October 25, 2007, 09:34 Re: patch: nothing happened..! #2 bashu Guest   Posts: n/a You are patching an initial guess or condition to the zones you have marked. If you don't change the BC you won't get a different answer just by patching. In transient you may get a different answer if your IC is changed.

 October 25, 2007, 10:27 Re: patch: nothing happened..! #3 chun wee Guest   Posts: n/a Hi Bashu, Thanks for answering. I ran the duct without the pressure patch (case I), after few thousands of iteration, I stopped iterating and recorded the results. Then, I patched the pressure at duct inlet and outlet (case II). Shouldn't these two give different results. If not, then how is the correct procedure for patching pressure? Thank you

 October 25, 2007, 12:30 Re: patch: nothing happened..! #4 bashu Guest   Posts: n/a If you are trying to model your case with different pressure drops you have to set it in BC panel. Patching is for assigning a value to a ceratin zone at the beginning of your iteration but the zone won't maintain its value. If I misunderstood your question, please explain more.

 October 26, 2007, 00:13 Re: patch: nothing happened..! #5 sheila Guest   Posts: n/a Hi Bashu, I want to make a transient case, by changing the pressure at the inlet and outlet of the duct in the middle of iteration. I did it like this: Ran without patch -> stop iteration (plot the pressure) -> patch pressure at duct's inlet and outlet -> converge -> plot the pressure -> compare the two plot results Is this correct? If not, can you please tell me the correct way of doing it? Thank you

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