Zero gradient Temperature Bc

October 3, 2007, 07:08

Hi all, I need to specify zero static avarage pressure,and zero temprature gradient at the outlet. How can I do this in cfx 11?

Thanks in advance, Selim

October 3, 2007, 19:32

Hi,

You cannot specify temperature (or temperature gradient) at an outlet. The temperature at the outlet is defined by the flow upstream only. What are you trying to do?

Glenn Horrocks

October 4, 2007, 02:56

Can't you specify temperature gradient at the outlet by using the "outlet" boundary condition? Isn't the "outlet" boundary conditions second derivatives equal to 0? So you are indirectly specifying a temperature gradient by choosing the outlet condition.

October 4, 2007, 19:20

Hi,

From the CFX V11SP1 theory manual, outlet boundary conditions: "For scalar quantities, the ANSYS CFX-Solver imposes a constant gradient constraint (generally non-zero) at the outlet boundary."

It does not define what gradient it does actually impose or how it is calculated. Does anyone know this?

Regards, Glenn Horrocks

October 3, 2007, 07:08	Zero gradient Temperature Bc	#1
selim Guest Posts: n/a	Hi all, I need to specify zero static avarage pressure,and zero temprature gradient at the outlet. How can I do this in cfx 11? Thanks in advance, Selim

October 3, 2007, 19:32	Re: Zero gradient Temperature Bc	#2
Glenn Horrocks Guest Posts: n/a	Hi, You cannot specify temperature (or temperature gradient) at an outlet. The temperature at the outlet is defined by the flow upstream only. What are you trying to do? Glenn Horrocks

October 4, 2007, 02:56	Re: Zero gradient Temperature Bc	#3
S. Guest Posts: n/a	Can't you specify temperature gradient at the outlet by using the "outlet" boundary condition? Isn't the "outlet" boundary conditions second derivatives equal to 0? So you are indirectly specifying a temperature gradient by choosing the outlet condition.

October 4, 2007, 19:20	Re: Zero gradient Temperature Bc	#4
Glenn Horrocks Guest Posts: n/a	Hi, From the CFX V11SP1 theory manual, outlet boundary conditions: "For scalar quantities, the ANSYS CFX-Solver imposes a constant gradient constraint (generally non-zero) at the outlet boundary." It does not define what gradient it does actually impose or how it is calculated. Does anyone know this? Regards, Glenn Horrocks

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