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-   -   CFX4.2 multi-fluid model (http://www.cfd-online.com/Forums/main/953-cfx4-2-multi-fluid-model.html)

wan xiaotao June 28, 1999 04:31

CFX4.2 multi-fluid model
 
I have two questiona about the CFX multifluid model: 1. In the CFX multi-fluid model,the convection term in the momentum equation is

div(ra(aUaUa-agrad(Ua)))

Clearly the viscosity a is the value of single phase.If the concerned phase is gas or liquid ,there is no confusion.But if solid kinetic model is used ,is there a single phase viscosity value? For example,one use the Gidaspows theory to calculate the s,the s is the single phase value just analogous to gas phase or it has included the effect of phase fraction ra. 2. In the gas phase,some term in the shear stress is absorbed in the pressure. This term is (2/3-)div(U).If the gas phase is incompressible in single phase,this term is equal to 0. Can the single phase incompressible conception be extend to multiphase model,and just set this term and the similar term in solid phase to 0.

best regards,

Wan xiaotao


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