The difference of cyclic boundry condition and mapped boundary condition

caitao · January 29, 2015, 23:25

Hi
I am runing a case in which the domain is a simple open channel flow. I want to get the state of the full development of boundary layer, but for the computational cost, my channel is much shorter than the actual.
So I use two kinds of boundary condition on the INLET and OUTLET.
First， I use the cyclic boundry condition, patching the INTLET with the OUTLET. however, i find it can only set an initial internal velocity, the velocity on INLET or OUTLET can not be set. What's more, with the caculation, the velocity in the domain will reduce.
Second, I use the mapped boundry condition, patching the INTLET with the OUTLET. In this type of boundry condition, I can set the velocity of INLET or OUTLET.and with the caculation, the velocity in the domain wouldn't reduce.

So do anyone know the difference between this two kinds of boundary condition? Maybe we can have a discussion.

kiski · December 4, 2019, 08:29

Hi Caitao,
Did you find the answer to this question?

January 29, 2015, 23:25	The difference of cyclic boundry condition and mapped boundary condition	#1
caitao New Member Cai Tao Join Date: Oct 2014 Location: China shanghai Posts: 7 Rep Power: 12	Hi I am runing a case in which the domain is a simple open channel flow. I want to get the state of the full development of boundary layer, but for the computational cost, my channel is much shorter than the actual. So I use two kinds of boundary condition on the INLET and OUTLET. First， I use the cyclic boundry condition, patching the INTLET with the OUTLET. however, i find it can only set an initial internal velocity, the velocity on INLET or OUTLET can not be set. What's more, with the caculation, the velocity in the domain will reduce. Second, I use the mapped boundry condition, patching the INTLET with the OUTLET. In this type of boundry condition, I can set the velocity of INLET or OUTLET.and with the caculation, the velocity in the domain wouldn't reduce. So do anyone know the difference between this two kinds of boundary condition? Maybe we can have a discussion. kiski likes this.

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December 4, 2019, 08:29		#2
kiski New Member David Join Date: Mar 2012 Posts: 17 Rep Power: 14	Hi Caitao, Did you find the answer to this question?