Triangular mesh - fully developed flow between parallel plate

Amir_Ghasemi · November 25, 2010, 12:54

Dear Friends,

I want to simulate a fully developed flow between infinite parallel plate (2-D), with prescribed pressure for inlet and outlet. When I use rectangular (structured) mesh, the results are consistent with analytical solution:

u = h ^ 2 (2 * mio) * ( Delta P / L) * ((y/h) ^ 2 - (y/a) )

but when I use 3-node triangular mesh (with any form I tested) the resulted velocity profile are not correct; lower velocity is obtained for a prescribed pressure gradient.

I tried finer triangular mesh, but no better results achieved.

I Use ADINA-8.5 Software which is finite element based.

Any suggestion and guidance is really appreciated.

otd · November 25, 2010, 18:44

Should (y/a) in your formula be (y/a)^2 ?

Amir_Ghasemi · November 26, 2010, 12:18

Thanks for your reply, it should be y/h, but this is not a mistake, there is a fundamental error in using triangular mesh, but I don't know what is that?

Amir_Ghasemi · November 28, 2010, 04:52

I changed the upwind type from Finite Element to Finite Volume in ADINA and know the results are correct

.
It can be found here in ADINA:

Control -> Miscellaneous option -> Default upwinding type > Finite Element

November 25, 2010, 12:54	Triangular mesh - fully developed flow between parallel plate	#1
Amir_Ghasemi New Member Amir Join Date: Oct 2010 Posts: 16 Rep Power: 15	Dear Friends, I want to simulate a fully developed flow between infinite parallel plate (2-D), with prescribed pressure for inlet and outlet. When I use rectangular (structured) mesh, the results are consistent with analytical solution: u = h ^ 2 (2 * mio) * ( Delta P / L) * ((y/h) ^ 2 - (y/a) ) but when I use 3-node triangular mesh (with any form I tested) the resulted velocity profile are not correct; lower velocity is obtained for a prescribed pressure gradient. I tried finer triangular mesh, but no better results achieved. I Use ADINA-8.5 Software which is finite element based. Any suggestion and guidance is really appreciated.

November 28, 2010, 04:52	Solved	#4
Amir_Ghasemi New Member Amir Join Date: Oct 2010 Posts: 16 Rep Power: 15	I changed the upwind type from Finite Element to Finite Volume in ADINA and know the results are correct. It can be found here in ADINA: Control -> Miscellaneous option -> Default upwinding type > Finite Element

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November 25, 2010, 18:44		#2
otd Member private Join Date: Mar 2009 Posts: 74 Rep Power: 17	Should (y/a) in your formula be (y/a)^2 ?

November 26, 2010, 12:18		#3
Amir_Ghasemi New Member Amir Join Date: Oct 2010 Posts: 16 Rep Power: 15	Thanks for your reply, it should be y/h, but this is not a mistake, there is a fundamental error in using triangular mesh, but I don't know what is that?