Implementation of the phase momentum equation in BubbleFoam
 

Dear all,

I´m new to OpenFoam and currently working on understanding the procedure of BubbleFoam. Therefore, I read the article of Henry Weller "Derivation, Modelling ans Solution of the Conditionally Averaged Two-Phase Flow Equations" which is cited in http://openfoamwiki.net/index.php/BubbleFoam. What I don´t fully understand is the connection between Weller´s phase momentum equation and the one implemented in BubbleFoam (see http://openfoamwiki.net/index.php/BubbleFoam section 4.3.1). In both equations, UaEqn and UbEqn, there seems to be a sign error in the liftCoeff term. As Weller describes it, it has to be positive in UaEqn and negative in UbEqn. Can anybody please help me understand this?

Thanks.