Y plus in fluid fluid interface

February 29, 2008, 08:18

Hai All,

I am doing simulation of a cooling fan with CHT model. In my mesh, I have a y plus value less than 1 for those close to the solid boundaries. I have divided the fluid domain in varoius domains for simplicity. At the fluid fluid interface, I have y plus values greater than 1. And one of the interface close to my fan but does not toouch it. Does it really have any effect on my simulation?

I guess not, since there is no solid boundary at this interface.

Thank you for your replies.

Regards,

Subha.

March 1, 2008, 09:43

this should be fine

March 2, 2008, 07:48

March 4, 2008, 08:29

It is necessary to maintain a good values of Y plus even for Fluid Fluid interface if you want simulate accurately.

March 4, 2008, 08:56

??? !!!

Why??? What is your logic?

Checks on Y+ should be used to ensure turbulent wall functions will work accurately at no-slip walls. In addition, when using low-Reynolds number turbulence models the value of Y+ is used to ensure boundary layers at no-slip walls are resolved. You can read the theory related to this in the CFX help system.

At a fluid-fluid interface there is no wall, and no boundary layer! Therefore the value of y+ is surely irrelevant.

What, therefore, makes you think y+ is important at a fluid-fluid interface?

February 29, 2008, 08:18	Y plus in fluid fluid interface	#1
Subha Guest Posts: n/a	Hai All, I am doing simulation of a cooling fan with CHT model. In my mesh, I have a y plus value less than 1 for those close to the solid boundaries. I have divided the fluid domain in varoius domains for simplicity. At the fluid fluid interface, I have y plus values greater than 1. And one of the interface close to my fan but does not toouch it. Does it really have any effect on my simulation? I guess not, since there is no solid boundary at this interface. Thank you for your replies. Regards, Subha.

March 1, 2008, 09:43	Re: Y plus in fluid fluid interface	#2
Hekler Guest Posts: n/a	this should be fine

March 2, 2008, 07:48	Re: Y plus in fluid fluid interface NM	#3
11 Guest Posts: n/a

March 4, 2008, 08:29	Re: Y plus in fluid fluid interface	#4
Santosh Guest Posts: n/a	It is necessary to maintain a good values of Y plus even for Fluid Fluid interface if you want simulate accurately.

March 4, 2008, 08:56	Re: Y plus in fluid fluid interface	#5
andy20 Guest Posts: n/a	??? !!! Why??? What is your logic? Checks on Y+ should be used to ensure turbulent wall functions will work accurately at no-slip walls. In addition, when using low-Reynolds number turbulence models the value of Y+ is used to ensure boundary layers at no-slip walls are resolved. You can read the theory related to this in the CFX help system. At a fluid-fluid interface there is no wall, and no boundary layer! Therefore the value of y+ is surely irrelevant. What, therefore, makes you think y+ is important at a fluid-fluid interface?

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