CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   STAR-CCM+ (http://www.cfd-online.com/Forums/star-ccm/)
-   -   VOF Model - (http://www.cfd-online.com/Forums/star-ccm/111389-vof-model.html)

RonBon January 5, 2013 15:49

VOF Model -
 
1 Attachment(s)
Hello,

I'm having difficulty with applying the Volume Fraction to my simulation (see image attached) and help would much appreciate.
I'm trying to simulated Water flowing into the funnel and filling up the container.

Initial conditions:the VF at the inlet is [1.0,0.0] (Water:Air) and the outlet VF is [0.0,1.0]
BC's: Inlet-Velocity(0.5m/s), Outlet-Pressure

From the tutorials on Multiphase simulations, I cannot figure out how to manipulate the Initial Distribution Field Function [($$Position[0]<=-1)?1:0)] to suit my project. I don't have alot of experience in this type of programming.

Can anyone help me?

abdul099 January 5, 2013 17:30

Where do you want to have water and where should be air after initializing?

RonBon January 5, 2013 18:22

1 Attachment(s)
I'm looking for the funnel and the container (rectangular region) in the beginning to contain be 100% Air. Then the water will flow down the funnel and will rise in the container to a certain level (still to be determined) resulting in the air be forced out of the north face of the rectangular region (Funnel & Container - Outlet).

I'm not certain if the water needs to be assigned to a region at initial conditions for the VOF modeling. If it is required I can define the funnel to be filled with water(see attachment) and the flow as a gravity driven flow.

I hope I'm not confusing matters?

Thanks for the quick response.

abdul099 January 5, 2013 19:06

When all should be filled with air at the beginning, just disable the field function input and set a constant volume fraction of 0.0,1.0.

You don't need to initialize the whole domain with water, you can choose any mixture (even a pure phase).

RonBon January 7, 2013 11:52

1 Attachment(s)
Thank you for pointing me in the right direction.
I have completed a few simulations now but from the results I obtained, it appears that the air and water are mixing together in a large region (see attachment). I don't understand why this is occurring. Is there a model property that I'm overlooking.?

Prashanth.A January 8, 2013 00:41

There is a better way to run the simulation, declare your volume(funnel and Container) as two different regions (red and blue ones). Once regions are in place, go to physical properties of the REGION and change the option Initial condition to region wise (do it for both the regions). Then you could specify two different volume fractions for regions you've wanted, initialize the simulation before you run it.

RonBon January 8, 2013 09:01

I don't see how you can assign two regions to my problem when its in a 2d profile and nothing separates the funnel from the container?

Prashanth.A January 8, 2013 10:39

If i amn't wrong, the funnel is inserted in the container. you could use operations at region level to specify these separately. I have once done a 2-d conjugate heat transfer which requires two separate regions.

Thanks

tloveyoudc January 8, 2013 11:33

b*i n*y hay th?t dó nha


All times are GMT -4. The time now is 22:57.