CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   STAR-CCM+ (http://www.cfd-online.com/Forums/star-ccm/)
-   -   free surface modelisation (http://www.cfd-online.com/Forums/star-ccm/98929-free-surface-modelisation.html)

hydraulic March 22, 2012 04:19

free surface modelisation
 
Dear all,

I am trying to model an open channel flow (free surface flow) in a pipe.
The requirement is to obtain the 3D turbulent structure, including turbulence-driven secondary currents.
I have tried innumerable strategies (combined inlet and seperate inlets....) with no luck in obtaining the expected results.
In CCM+, I have defined a field function to fix the water level at the inlet (and used the same for initialization) but the free surface disapears....

Prob definition:
Physics Models:
-Multiphase VOF
-Segregated Solver
-Turbulent -> K-e realiz
-Unsteady flow (Time step = 0.05s)
BC's:
-Combined Inlet: Velocity inlet [Magnitude = 0.5m/s)]
-Outlet: Pressure Outlet
-Turbulence specifications for Inlets and Outlets:
TI = 10%

Please have a look at the problem set up and sugest any change in strategy .

Thank you

Ladnam March 25, 2012 04:10

I think separate inlets is the best option, or maybe it will work using the flat wave model for combined inlet.
How does the interface disappear?

ryancoe March 25, 2012 14:36

Have you applied any control to the water level at the outlet?

abdul099 April 1, 2012 16:59

The water level at the outlet should be a result of the behaviour within the domain. Anyway, the pressure at the outlet should be set according to the expected water level.
Just a stupid question: Did you switch on gravity? Is the mesh fine enough?

hydraulic April 10, 2012 04:18

5 Attachment(s)
yes i switch on gravity,
i put my air with a velocity of 0.5m/s, the same for water.
I attached a picture of the water level at the end of the simulation. I can't attache my report on the original format, my file exceeds the forum's limit . So i put the screenshots

hydraulic April 10, 2012 04:21

3 Attachment(s)
Thanks again,


All times are GMT -4. The time now is 17:29.