# how to implement a boundary conditions on multiphase boundary in fluent?

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I'm having a bucket filled with water and oil on top of the water at high temperatures. That makes the problem with 3 phases (water, oil, and air). oil on top of the water and subsequently air on top of the oil. Schematic as shown below ( Phase ID: Blue = air, red = oil, green = water )

I use 'patch' for marking different phases on the cell zone.

I want to apply a boundary condition on the top surface of the oil layer, i.e at the oil-air interface.

e.g = Temperature radiation BC, air above is at 300K and Oil is at 500K.

Thus a mixed temperature boundary condition : (I) Radiation with external emissivity 0.7, so that heat dissipates to the ambient air, (ii) Convection with h= 20 W/m2 on the oil-air interface.

Thanks.

Hello,

If you are solving this as a multiphase problem, the oil-air interface is not a flow boundary, and therefore, you cannot apply a boundary condition there. Boundary conditions can be applied only to the external boundaries of your computational domain. If you are solving this as a Multiphase problem, the heat transfer between the oil and air phases (especially at the interface) will be accounted for by the solver when you solve this model. You don't need to explicitly specify conditions on this interface.

Karthik

• Posts: 100Member