Hello all,

I hope you are all familiar with the heat and mass trasfer example provided in the Fluent advanced tutorials.

The UDF in it has a calculation of mass flow rate.

if(cell mixture temp. >= sat. temp.)

mass flow rate of liquid = -0.1*liquid VOF*liquid density* normalized liquid temp. from saturation temp.

I am kind of confused here to understand a few things...

1) Is the unit of VOF of that of volume? 2) what is the 0.1 in this equation mean?

Thanks in advance,

Srinivas Parimi

The unit of VOF is not volume, it is just a parameter without unit.

The parameter of "0.1" is time relaxation and has a unit of "1/s"

This formula comes from Wenhe Lee(1975) who is Chinese like me.

Hello Joey,

Thank you for your response. If VOF has no units and 0.1 has units of 1/time, the dimensions dont add up on each sides of the equation. There is a volume term still missing.

Thanks in advance,

Srinivas Parimi

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