cavitation mass transfer rate

linlin.geng · November 16, 2017, 06:18

when we do cavitation simulation, if i want to use the user defined cavitation model rather than the Zwart model which is default model in CFX. I need to confirm that what is the default mass transfer equation, for liquid or for vapor.

when i resort to the CFX-Help, i found that the source term of mass transfer equation for cavitation has the term of vapor fraction rather than the liquid fraction. but when i carry cavitation simulation, there is a default moniter window for the volume fractions of water. so i am confused?

thanks for the possible answer.

PeMo · November 16, 2017, 08:15

CFX Modeling Guide Manual 7.15.4.2:

A user-defined cavitation model can be implemented for advanced users. It requires the following parameters:

Cavitation Rate: This should be set through CEL or User Fortran. The cavitation rate is simply , the interphase mass transfer rate per unit volume from the liquid to the vapor phase, assuming the first fluid in the fluid pair is the liquid and the second is the vapor. If the order in the pair is reversed, the sign must be reversed. As an example, the interphase mass transfer rate for the Rayleigh Plesset model in ANSYS CFX is given by The Rayleigh Plesset Model in the CFX-Solver Theory Guide.

linlin.geng · November 16, 2017, 11:55

Quote:

Originally Posted by PeMo

CFX Modeling Guide Manual 7.15.4.2:

A user-defined cavitation model can be implemented for advanced users. It requires the following parameters:

Cavitation Rate: This should be set through CEL or User Fortran. The cavitation rate is simply , the interphase mass transfer rate per unit volume from the liquid to the vapor phase, assuming the first fluid in the fluid pair is the liquid and the second is the vapor. If the order in the pair is reversed, the sign must be reversed. As an example, the interphase mass transfer rate for the Rayleigh Plesset model in ANSYS CFX is given by The Rayleigh Plesset Model in the CFX-Solver Theory Guide.

thanks for your answer, but my question is that what is the default equation of transfer mass rate, is this equation related to the sequence of fluid pair?

November 16, 2017, 06:18	cavitation mass transfer rate	#1
linlin.geng New Member linlin.geng Join Date: Oct 2017 Posts: 22 Rep Power: 9	when we do cavitation simulation, if i want to use the user defined cavitation model rather than the Zwart model which is default model in CFX. I need to confirm that what is the default mass transfer equation, for liquid or for vapor. when i resort to the CFX-Help, i found that the source term of mass transfer equation for cavitation has the term of vapor fraction rather than the liquid fraction. but when i carry cavitation simulation, there is a default moniter window for the volume fractions of water. so i am confused? thanks for the possible answer.

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November 16, 2017, 08:15		#2
PeMo Member Peter Join Date: Sep 2011 Location: Germany Posts: 39 Rep Power: 15	CFX Modeling Guide Manual 7.15.4.2: A user-defined cavitation model can be implemented for advanced users. It requires the following parameters: Cavitation Rate: This should be set through CEL or User Fortran. The cavitation rate is simply , the interphase mass transfer rate per unit volume from the liquid to the vapor phase, assuming the first fluid in the fluid pair is the liquid and the second is the vapor. If the order in the pair is reversed, the sign must be reversed. As an example, the interphase mass transfer rate for the Rayleigh Plesset model in ANSYS CFX is given by The Rayleigh Plesset Model in the CFX-Solver Theory Guide.