[pygmi]

Hello, Fluent users,

I'm trying to simulate the air-water flow in a simple lectangular channel.
The channel is parallel to the ground.
Because there are paddle wheels at the inlet and outlet, water level is constant and maintained along the channel.
I want the free surface levels at both the inlet and outlet to be the same.

To make the system simple, I removed paddle wheels and set the boundarys as pressure inlet/outlet.
I use VOF model and set Eulerian two phase.
I can specify free surface levels at both of pressure inlet and outlet. (boundary conditions)

I have a question in that point.
Does the program calculate the free surface level at the outlet from the boundary condition of the inlet, automatically? If so, is calculated outlet surface level and inlet surface level the same?

Or

Should I specify the levels at both the inlet and outlet the same?

I will be very grateful for your help.

[masoud.ravan]

Originally Posted by pygmi

Hello, Fluent users,

I'm trying to simulate the air-water flow in a simple lectangular channel.
The channel is parallel to the ground.
Because there are paddle wheels at the inlet and outlet, water level is constant and maintained along the channel.
I want the free surface levels at both the inlet and outlet to be the same.

To make the system simple, I removed paddle wheels and set the boundarys as pressure inlet/outlet.
I use VOF model and set Eulerian two phase.
I can specify free surface levels at both of pressure inlet and outlet. (boundary conditions)

I have a question in that point.
Does the program calculate the free surface level at the outlet from the boundary condition of the inlet, automatically? If so, is calculated outlet surface level and inlet surface level the same?

Or

Should I specify the levels at both the inlet and outlet the same?

I will be very grateful for your help.

Hi
Did you get your answer?? I have the same problem with OPEN CHANNEL FLOW? How can I fix the water level?
Thanks in advance

[ANKURIITD]

Originally Posted by masoud.ravan

Hi
Did you get your answer?? I have the same problem with OPEN CHANNEL FLOW? How can I fix the water level?
Thanks in advance

use open channel VOF model in fluent. By enabling this condition at pressure inlet and pressure outlet you just give free surface level and bottom surface. It will automatically calculate the free surface and will patch the secondary phase from free surface to the bottom surface.

You can check it by plotting the contour of volume fraction at any surface after initialization.

[masoud.ravan]

Originally Posted by ANKURIITD

use open channel VOF model in fluent. By enabling this condition at pressure inlet and pressure outlet you just give free surface level and bottom surface. It will automatically calculate the free surface and will patch the secondary phase from free surface to the bottom surface.

You can check it by plotting the contour of volume fraction at any surface after initialization.

Thank you very much
but how can I initialize the problem?

[ANKURIITD]

Originally Posted by masoud.ravan

Thank you very much
but how can I initialize the problem?

after setting up the boundary conditions, solution methods and solution control, go to the solution initialization dialog box and setup the followings:

initialization method: standard
compute from: up inlet
reference frame: relative to the cell zone
open channel initialization method: flat
now see the magnitudes of the variables in the initial value box, here just check the velocities. let the water/secondary phase volume fraction be 0.
click initialize.