Hi all,

I want to know whether i can use the additional variable concept for the problem i am solving. The problem is to simulate the bioreactor (two phase Liq-Gas system), but we are solving the single phase (only Liq) problem with gas phase replaced by free-slip wall. Here we need to account for the mass transfer tanking place through free-slip wall (i.e. liq-gas interface in actual practice).

The mass transfer of species leads to change in partial pressure ingas phase and intern may be liquid concentrations. And this process in function of time as well. I want to try the partial pressures of gas phase as addtional variables.

Thanks in advance Regards Tuks The partial pressures are varying with time. Can i use the algebric equations for additaional variables? The difficulty i am facing is the variation w.r.t time.

Additional Variables don't affect the flow, so you can't use this approach. You may be able to use a Boundary Source Term (in CFX-10), the difficult part is figuring out source terms to add to the appropriate equations. Mike