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-   -   Reversed flow in pressure inlet (http://www.cfd-online.com/Forums/fluent/32876-reversed-flow-pressure-inlet.html)

eric January 19, 2004 10:22

Reversed flow in pressure inlet
 
Hi,

I am simulating flow in a box with two inlets, one velocity and one pressure inlet, and one outlet. The pressure inlet is just an opening in the box but the velocity inlet has a flowrate.

I know that air is entrained from the atmosphere into the box domain through the opening but I do not have any measurements. This is why I set the opening as a pressure inlet - setting gauge pressure to zero i.e atmospheric pressure. Is this right?

Also, I am getting reversed flow in x faces at the pressure inlet and even after 1000 iterations and variables = 10e-05 this warning has not dissappeared.

Will this cause errors in the solution and if so is there a way of eliminating it, i.e. thro grid refining or relaxing the pressure urf??

Thanks for your help,

Eric

eric January 21, 2004 05:52

Re: Reversed flow in pressure inlet
 
I'm really stuck on this!!!

Can anyone help?

Thanks

Eric

Trilok January 23, 2004 06:58

Re: Reversed flow in pressure inlet
 
I dont think it will cause any error in solution..reversed flow you may expect at that location..u can just ignore the warning of reversed flow... the second way is you can increase the lenght of your domain at the section where u r getting reversed flow in order to avoid this... Hope this helps

Anton January 26, 2004 21:04

Re: Reversed flow in pressure inlet
 
All it means is that you do indeed have flow being exhausted out through the pressure inlet. It won't cause errors. Now you may be noticing that the continuity equation is struggling a little bit to converge, and that's because you have cells right adjacent to each other where flow is entering and exiting the domain. So Fluent is having a bit of trouble resolving that. It may flipflop, some cells the flow goes in, other times it goes out. It's okay as long as you check that you have a global mass balance and that the net mass entering or leaving that pressure inlet is no longer changing significantly with further iteration.


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