boundary condition for straight 3D open chnannel

moon1234 · March 15, 2010, 03:47

I am setting up a problem on 3D straight open channel flows........can any one suggest me the boundary conditions to be imposed during meshing in Gambit?

vmeertens · March 15, 2010, 06:25

Hi,

I'm also doing a case with 3D open channel.

For inlet and outlet i use: Pressure Inlet and Pressure Outlet.
For your plate you should use wall. (in fluent this will be a stationary wall)
If you have a brick (flow volume) then your BC for the rest of the sides should be wall (in fluent i define them as moving walls with the same speed as the fluid)

Hope this helps.

Philipov · March 15, 2010, 06:39

BC depends on what you know... inlet velocity, Pressure inlet, mass flowrate and so on.... we do not know that information....
Using Pressure inlet and Pressure outlet assume compressibility of the fluid that is not known also... BC must be set to property that you can compare to any reference value...... rearrange the question and ask again when you can give more details and have more information about the task....

moon1234 · March 15, 2010, 07:41

wat about freesurface...........wat would be the BC for top surface
i have two option in it............
1. To apply pressure inlet
2. moving wall

vmeertens · March 15, 2010, 07:46

Hey,

Philipov is right, i replied to soon...
I assumed it was just water and air with a constant inlet speed.

The free surface doesn't need a BC (if i'm correct

) This is done in Fluent and not in Gambit.

moon1234 · March 15, 2010, 07:57

yeah buddy this is done in fluent after completion of meshing

moon1234 · March 15, 2010, 07:59

but about boundary condition to free surface

March 15, 2010, 03:47	boundary condition for straight 3D open chnannel	#1
moon1234 New Member Mrityunjay sahu Join Date: Jan 2010 Location: Sydney,Australia Posts: 11 Rep Power: 16	I am setting up a problem on 3D straight open channel flows........can any one suggest me the boundary conditions to be imposed during meshing in Gambit?

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March 15, 2010, 06:25		#2
vmeertens Member Vincent Meertens Join Date: Sep 2009 Location: Belgium Posts: 41 Rep Power: 17	Hi, I'm also doing a case with 3D open channel. For inlet and outlet i use: Pressure Inlet and Pressure Outlet. For your plate you should use wall. (in fluent this will be a stationary wall) If you have a brick (flow volume) then your BC for the rest of the sides should be wall (in fluent i define them as moving walls with the same speed as the fluid) Hope this helps.

March 15, 2010, 06:39		#3
Philipov Senior Member Svetlin Filipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 17	BC depends on what you know... inlet velocity, Pressure inlet, mass flowrate and so on.... we do not know that information.... Using Pressure inlet and Pressure outlet assume compressibility of the fluid that is not known also... BC must be set to property that you can compare to any reference value...... rearrange the question and ask again when you can give more details and have more information about the task....

March 15, 2010, 07:41		#4
moon1234 New Member Mrityunjay sahu Join Date: Jan 2010 Location: Sydney,Australia Posts: 11 Rep Power: 16	wat about freesurface...........wat would be the BC for top surface i have two option in it............ 1. To apply pressure inlet 2. moving wall

March 15, 2010, 07:46		#5
vmeertens Member Vincent Meertens Join Date: Sep 2009 Location: Belgium Posts: 41 Rep Power: 17	Hey, Philipov is right, i replied to soon... I assumed it was just water and air with a constant inlet speed. The free surface doesn't need a BC (if i'm correct ) This is done in Fluent and not in Gambit.

March 15, 2010, 07:57		#6
moon1234 New Member Mrityunjay sahu Join Date: Jan 2010 Location: Sydney,Australia Posts: 11 Rep Power: 16	yeah buddy this is done in fluent after completion of meshing

March 15, 2010, 07:59		#7
moon1234 New Member Mrityunjay sahu Join Date: Jan 2010 Location: Sydney,Australia Posts: 11 Rep Power: 16	but about boundary condition to free surface