[giack]

Hi to all,
i am a bit confused in the computed of U in the pEqn.H of interFoam
why is computed as follow?
U += rAU*fvc::reconstruct((phi - phiU)/rAUf)

I compare it with the PISO algorithm in wich U is computed as:
U -= rUA*fvc::grad(p);

thanks to all

[fumiya]

This topic is discussed in several threads:

• http://www.cfd-online.com/Forums/ope...-pressure.html
  The post #9 by alberto is especially helpful.
• http://www.cfd-online.com/Forums/ope...qpisofoam.html

The following documents cover most of the points about interFoam including this topic:

• Description and utilization of interFoam multiphase solver
  https://docs.google.com/viewer?a=v&q...7x3fkYvPAzRccA
  
• Computational Fluid Dynamics of Dispersed Two-Phase Flows at High Phase Fractions
  http://powerlab.fsb.hr/ped/kturbo/Op...chePhD2002.pdf

Regarding the "reconstruct" function, you might want to see the following thread:

• http://www.cfd-online.com/Forums/ope...algorithm.html

Best regards,
Fumiya

[giack]

Thank you very much for your help
I have another question: in the first document that you send me the compression term is discretized as show in 114 but in i look in the code and the discretization is different. In the code, in fact, is used a quadratic compression scheme as follow:

min(max(4*min(phiP*(1 - phiP), phiN*(1 - phiN)), 0), 1)

the two scheme are similar?what is better?

Thank you very much for your willingnes