Inlet boundary conditions from profile data

M_Tidswell · April 15, 2013, 14:38

Dear All

I have applied an inlet boundary condition from a previous simulations outlet using profile data and it looks great for the first 20mm or so however.... just after that a section of essentially stationary fluid develops for about 300mm right against the wall like a very shallow bump. This doesn't exist in the full size flow so it is developing due to the implementation of the profile data inlet condition.
Has anyone else come across this? Is there any way to eliminate it?
I have tried manipulating the data a bit to see if it is an issue with the velocity data but it appears not.

Many thanks

Mark

ghorrocks · April 15, 2013, 19:09

Please post an image. But as you describe it is probably the flow developing from your inlet condition to a flow more suited to the geometry, and that transition involves a separation.

M_Tidswell · April 29, 2013, 09:17

Hi

It turned out there was an adverse pressure gradient that the velocity inlet was not accounting for. I tried using a total pressure and direction inlet with far more positive results, thank you for your input it hadn't occurred to me that the outlet would only sample the selected variable. By drawing a line at the point i was reducing the domain too in tandem with a total pressure and direction option the feature is far less dominant.

Many thanks once again

Mark

April 15, 2013, 14:38	Inlet boundary conditions from profile data	#1
M_Tidswell Member Mark Join Date: Feb 2013 Location: London Posts: 33 Rep Power: 13	Dear All I have applied an inlet boundary condition from a previous simulations outlet using profile data and it looks great for the first 20mm or so however.... just after that a section of essentially stationary fluid develops for about 300mm right against the wall like a very shallow bump. This doesn't exist in the full size flow so it is developing due to the implementation of the profile data inlet condition. Has anyone else come across this? Is there any way to eliminate it? I have tried manipulating the data a bit to see if it is an issue with the velocity data but it appears not. Many thanks Mark

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April 15, 2013, 19:09		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Please post an image. But as you describe it is probably the flow developing from your inlet condition to a flow more suited to the geometry, and that transition involves a separation.

April 29, 2013, 09:17		#3
M_Tidswell Member Mark Join Date: Feb 2013 Location: London Posts: 33 Rep Power: 13	Hi It turned out there was an adverse pressure gradient that the velocity inlet was not accounting for. I tried using a total pressure and direction inlet with far more positive results, thank you for your input it hadn't occurred to me that the outlet would only sample the selected variable. By drawing a line at the point i was reducing the domain too in tandem with a total pressure and direction option the feature is far less dominant. Many thanks once again Mark