UDM (user-defined memory) boundary condition?

tstorm · September 30, 2010, 14:03

I've written a k-w-v2-f turbulence model, where epsilon is stored as a user-defined memory term. I need to set the boundary condition for epsilon at an inlet.

Does anyone know how to set a boundary condition for user-defined memory terms?

solefire · October 1, 2010, 06:04

I also have similar prob for uds bc..expecting

tstorm · October 1, 2010, 11:04

Do you mean UDM BCs? UDS BCs are simple, I can help you with that if you'd like.

solefire · October 1, 2010, 14:17

Quote:

Originally Posted by tstorm

Do you mean UDM BCs? UDS BCs are simple, I can help you with that if you'd like.

Thanks a lot!

For specified flux at outlet (pressure outlet)

I am wondering what does specified flux means exactly?

and there is one part (even i choose specified flux), i need to fill in the specified value, for one thing it is difficult to know; another thing, I put roughly guessing value there. it turned out 0 and 1 , there is not influence for the result at all.

could u give me some hint? thanks!

tstorm · October 1, 2010, 14:36

The flux is the rate of flow. A specified flux of 0 for a UDS at a wall, for example, would mean that there's no change in the UDS value between the wall and the first cell above the wall. I generally use a specified flux of 0 when I don't know the boundary condition - like at an inlet or outlet.

solefire · October 1, 2010, 15:44

Thank you a lot! that is very clear

September 30, 2010, 14:03	UDM (user-defined memory) boundary condition?	#1
tstorm Member Join Date: Apr 2009 Posts: 78 Rep Power: 17	I've written a k-w-v2-f turbulence model, where epsilon is stored as a user-defined memory term. I need to set the boundary condition for epsilon at an inlet. Does anyone know how to set a boundary condition for user-defined memory terms?

October 1, 2010, 06:04	how to clean up fluent working directory history	#2
solefire Member CJ Join Date: Jun 2009 Posts: 34 Rep Power: 17	I also have similar prob for uds bc..expecting

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October 1, 2010, 11:04		#3
tstorm Member Join Date: Apr 2009 Posts: 78 Rep Power: 17	Do you mean UDM BCs? UDS BCs are simple, I can help you with that if you'd like.

October 1, 2010, 14:36		#5
tstorm Member Join Date: Apr 2009 Posts: 78 Rep Power: 17	The flux is the rate of flow. A specified flux of 0 for a UDS at a wall, for example, would mean that there's no change in the UDS value between the wall and the first cell above the wall. I generally use a specified flux of 0 when I don't know the boundary condition - like at an inlet or outlet.

October 1, 2010, 15:44		#6
solefire Member CJ Join Date: Jun 2009 Posts: 34 Rep Power: 17	Thank you a lot! that is very clear