# Fluid flowing in opposite direction (normal to boundary)

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 July 16, 2020, 09:13 Fluid flowing in opposite direction (normal to boundary) #1 New Member   Join Date: Apr 2016 Posts: 5 Rep Power: 10 Hello everyone, I searched the forum for similar issues but didn't find any so I'm posting. If there are any similar threads, please direct me to them. My issue is this: I have a geometry that has a pressure inlet and pressure outlet. When I defined the BCs, I set these with their respective values and for direction, I set as Normal to Boundary. Logically, the flow should go from inlet to outlet. The issue is that the fluid is not 'entering' through the inlet. It is instead 'leaving' the pipe. I have simulated similar cases before so I am not sure why this time, the flow is moving in opposite direction. I have also tried to determine the direction of the flow myself using vector coordinates but the flow insists on leaving the channel and not entering it. I am sure the channel is defined as a fluid so I am really not sure what is going on here. Any help is appreciated. Here is my geometry: (I have a domain (fluid) surrounding this, as I am interested in the fluid properties once the fluid leaves the channel) https://ibb.co/MS3nXgD Here are the velocity vectors I am obtaining: https://ibb.co/VTwNpv1 Please direct me towards what may be causing the problem. (My mesh is of really good quality and time-step is small (e-06). Thanks!

 July 18, 2020, 05:57 #2 New Member   Join Date: Apr 2016 Posts: 5 Rep Power: 10 any help anyone?

 July 18, 2020, 07:02 #3 Member     Guven Nergiz Join Date: Jul 2020 Location: Turkey Posts: 52 Rep Power: 6 Hi Tobe, It seems like you have tried everything as possible solutions. You are certainly sure about your vector inputs, right? (please try both directions) And, are you solving compressible flow? If its not, could you try velocity inlet (with pressure outlet)? I hope you can solve this problem. Best regards, Güven

July 18, 2020, 18:27
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 Originally Posted by Guvennergiz Hi Tobe, It seems like you have tried everything as possible solutions. You are certainly sure about your vector inputs, right? (please try both directions) And, are you solving compressible flow? If its not, could you try velocity inlet (with pressure outlet)? I hope you can solve this problem. Best regards, Güven
I am sure the direction vectors I put are correct. But even then, Fluent sends part of the flow into the channel and most of it out. It's really strange and i can't figure out why.

My flow is compressible. I will try the velocity inlet with pressure outlet and see if that makes things better.

Thanks Güven!

 Tags ansys, fluent, fluid flow