how to set BC for flow at a sharp open-channel junction?

ntchuyen · July 16, 2013, 23:45

Hi everyone,

I am simulating 3D flow at a sharp open-channel junction. I use the solver interFoam with k-epsilon model. At initial time, I set BC as the figure in attached file.
The result is very strange. It looks like having a strong flow from the wall opposite of tributary channel to push water cross the main channel.

Do you meet this error? Please give me your advise.

Thank you very much.

vatavuk · July 17, 2013, 08:28

Hi Chuyen,
Welcome to the fórum!
The inlet velocities in the two inlet surfaces are in the same direction (0 0.6 0). The velocities should be in directions normal to the surfaces.
Best Regards,
Paulo

ntchuyen · July 17, 2013, 10:35

Hi Paulo,

Thank you for your reply.

But at the main inlet, the normal direction of surface is x-direction and at the tributary inlet, the normal direction of surface is y-direction. So I set the velocity Um = ( 0.06 0 0 ) (x-direction) at the main inlet, and Ub = ( 0 0.6 0 ) (y-direction) at the tributary inlet (the velocities at two inlets are different). is it wrong?

It's really doing my head in.

Best regard,

Chuyen.

ntchuyen · July 18, 2013, 07:57

Hi everybody,

I'm sorry for annoying everyone. I just fix my error. It is due to the mistake of gravity direction.

Thank you very much.

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July 17, 2013, 08:28		#2
vatavuk Senior Member Paulo Vatavuk Join Date: Mar 2009 Location: Campinas, Brasil Posts: 200 Rep Power: 18	Hi Chuyen, Welcome to the fórum! The inlet velocities in the two inlet surfaces are in the same direction (0 0.6 0). The velocities should be in directions normal to the surfaces. Best Regards, Paulo

July 17, 2013, 10:35		#3
ntchuyen New Member Chuyen Nguyen Join Date: Jul 2013 Posts: 4 Rep Power: 13	Hi Paulo, Thank you for your reply. But at the main inlet, the normal direction of surface is x-direction and at the tributary inlet, the normal direction of surface is y-direction. So I set the velocity Um = ( 0.06 0 0 ) (x-direction) at the main inlet, and Ub = ( 0 0.6 0 ) (y-direction) at the tributary inlet (the velocities at two inlets are different). is it wrong? It's really doing my head in. Best regard, Chuyen.

July 18, 2013, 07:57		#4
ntchuyen New Member Chuyen Nguyen Join Date: Jul 2013 Posts: 4 Rep Power: 13	Hi everybody, I'm sorry for annoying everyone. I just fix my error. It is due to the mistake of gravity direction. Thank you very much.