Even with different superheat amount of vapor is same

rupak504 · March 7, 2020, 02:17

hello,

I am simulating a film boiling phenomenon.

I am using following models:

Multi-phase: VOF
Scheme: Implicit
Turbulence: k-e
Methods: default
Controls: default
Phase change: Lee model (r = 0.1)

My Problem is: Very little difference (almost overlapping in graph) in amount of vapor generation even when degree of super-heat is increased by 45K.

regards

vinerm · March 7, 2020, 07:34

What's the fraction of vapor at the initialization? The model requires a positive vapor fraction at initial stage.

rupak504 · March 8, 2020, 00:41

Quote:

Originally Posted by vinerm

What's the fraction of vapor at the initialization?

At the initialization the fraction of vapor is zero.

Quote:

Originally Posted by vinerm

The model requires a positive vapor fraction at initial stage.

Why so?

vinerm · March 8, 2020, 04:29

The way the model is implemented, it checks for the minimum value of both phases to determine the mass transfer. If vapor fraction is always zero, the mass transfer will never begin.

March 7, 2020, 02:17	Even with different superheat amount of vapor is same	#1
rupak504 Senior Member Lolita Join Date: Aug 2016 Posts: 115 Rep Power: 9	hello, I am simulating a film boiling phenomenon. I am using following models: Multi-phase: VOF Scheme: Implicit Turbulence: k-e Methods: default Controls: default Phase change: Lee model (r = 0.1) My Problem is: Very little difference (almost overlapping in graph) in amount of vapor generation even when degree of super-heat is increased by 45K. regards

March 7, 2020, 07:34	Pre-existing Vapor	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	What's the fraction of vapor at the initialization? The model requires a positive vapor fraction at initial stage. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

March 8, 2020, 04:29	EC model Implementation	#4
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	The way the model is implemented, it checks for the minimum value of both phases to determine the mass transfer. If vapor fraction is always zero, the mass transfer will never begin. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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