CFD Online Discussion Forums - Bubble Modeling in Star-CCM+

Hi abdul,

I also need to simulate a similar case in a 3-phase model, which is liquid-liquid-gas system. My domain is a rectangular tank where it has two immiscible liquids (oil and water). A gas bubble is in the bottom of the tank moving upwards. How can I define the surface of the gas bubble as a no-slip condition? That means the gas bubble can be properly treated as a solid sphere. After the gas bubble surrounded by water goes through the liquid-liquid interface in the tank, the sphere will be surrounded by the oil as similar as the situation described above. How can I modify the physical condition for the liquid-liquid interface on the gas bubble? The boundary condition between liquid-liquid interface when the gas bubble moves upwards needs to be no-slip as well.

Any suggestions and advice are appreciable!! Expecting your reply!!
Many thanks!!

Enron

Quote:

Originally Posted by abdul099 (Post 381946)

I run a 2D case, so I created a 3D mesh and converted it to a 2D mesh. This means, there is only one cell layer in the z-direction.

I've initialized the domain with a square, by using a field function:
$$Position[0]>=0.045&&$$Position[0]<=0.055&&$$Position[1]>=0.015&&$$Position[1]<=0.025?1:0
A circle would work in a similar way, e.g. sqrt(pow($$Position[0],2)+pow($$Position[1],2))<="radiusOfTheBubble"?1:0 (Not tested). It also might work with local coordinate systems, just have a look in the user guide.
In 3D, it works exactly the same way, you just need to add the third dimension in a similar way.

I've used a pressure outlet boundary condition at the top. A little of the liquid will disappear through the boundary, but I didn't care since it was only a test case. You might put the boundary a little away from the position you want to have liquid surface and initialize according to the intended liquid level.
To make sure there will be no liquid enter the domain, you just need to specify the right volume fraction. Nothing magic.

I could send you the sim-file, but you won't be able to open it. You can't open a sim-file created with a specific version with an older version of Star-CCM+.