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SEM ; 0<VFOL<1

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Old   August 1, 2000, 12:56
Default SEM ; 0<VFOL<1
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In case of scalar eqution method (SEM), the equation of scalar advection is:

d(PHI)/dt + div(PHI*U)=0

This equation gives us values of VFOL (=PHI) who is the volume fraction of liquid, And we can solve this equation with Van Leer scheme for exemple.

1- How we are sure that the value of VFOL is always between 0 and 1 ? If not, can we do this (like in HOL method)?

if VFOL<0 , so VFOL= max(0,VFOL)

if VFOL>1 , so VFOL= min(1,VFOL)

2- is it the inlet and outlet conditions who fixed the range of VFOL ?

Best regards.

Applied Mathematics Laboratory, National Engineering School of Tunisia

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Old   March 8, 2001, 12:35
Default Re: SEM ; 0<VFOL<1
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Dear Mehdi

You can be sure by inserting this into your Q1 file: maxval(vfol)=1.0;minval(vfol)=0.0 maxval(surn)=1.0;minval(surn)=0.0

You should not forget the variable SURN in SEM wich is the most important. It is the "real" volume of fluid in each time step, I mean, the calculated volume of liquid after equation integration.

Nevertheless, if you have a re-compilable version of Phoenics, you should check the volume conservation for each time step. You will be surprised.

On other hand, boundary conditions have nothing to do with the limits of this variables.

Best wishes

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