Learning Forum

[abhnv_01]

Hello,

I am working on a two phase transient model, using VOF-multiphase model.

My model has three section: evaporator, condenser and adiabatic section.

primary phase - liquid

secondary phase - vapor

phase interaction - evaporation-condensation model (LEE model)

surface tension = continuum surface force, wall adhesion, jump adhesion

I am initializing my solution as:

Temperature = Condenser temperature

Pressure = Saturation pressure at condenser temperature

I have created a register and I have patched with 100% volume fraction of vapor in that region.

Evaporator = Constant Heat flux

Condenser = Constant temperature

Adiabatic section = zero heat flux

The starting problem that I am facing is that the research papers that I am referring to have claimed that they first give constant temperature boundary conditions to all three sections so as to get RANDOM DISTRIUTION OF LIQUID SLUGS AND VAPOR PLUGS (formed due to surface tension force and gravity force), once the RANDOM DISTRIBUTION IS ACHIEVED, then they give constant heat flux, and zero heat flux to evaporator and adiabatic section respectively.

But I am not able to get this distribution and I am not able to track the reason for this.

Any help will be highly appreciated.

thanks

Abhinav

[DrAmine]

Hmm I do not understand how they did that: contact the authors. I might think first everything is set at saturation temperature with temperature dependent surface tension then energy is disabled so that flow and curvature establish themselves. Please contact ­ƒÖÅ the authors

[DrAmine]

And share the title of the article

[abhnv_01]

Thank you for your suggestions.
Also, you want me to share the title of the article here?

[abhnv_01]

One thing that I would like to share with you regarding the above mentioned issue is that, when I patched the entire domain with a Volume Fraction of 50%, after running around 2000 time steps, I got the random distribution of liquid slugs and vapor plugs.
But 50% volume fraction for the entire domain will be a case of "DISPERSED FLOW', and VOF-model is used for free surface flows. So, it kind of violates the VOF-modelling.
So, I would again ask you, considering the above mentioned case, how this random distribution can be achieved? I have tried multiple ways to do so, but failed.

[Rob]

How is it done in the paper?

[abhnv_01]

In the paper they have done it as :
They first give constant temperature thermal boundary conditions to all three sections so as to get RANDOM DISTRIUTION OF LIQUID SLUGS AND VAPOR PLUGS (formed due to surface tension force and wall adhesion), once the RANDOM DISTRIBUTION IS ACHIEVED, then they give constant heat flux, and zero heat flux to evaporator and adiabatic sections respectively.

[Rob]

I have no idea. If you patch with 50% it's going to cause problems with VOF, but flow will be random. The above doesn't make sense without knowing how they got the liquid & vapour distribution set up.

[abhnv_01]

Thank you for your time.