which solver to model a falling film with mass transfer ?
 

Hi everybody!

I need to model the diffusion in a falling film along a wall. My system is a 2 phases flow (Gas + Liquid), however in a first time I will assume that the gas velocity is null. I suppose my interfacial condition is controled by Henry's law.

which solver can i use to simulate my problem ??

Thank you for helping

Hi Cyp,

well, did you have a look at

H. Raach and S. Somasundaram,
NUMERICAL INVESTIGATIONS ON HEAT TRANSFER IN
FALLING FILMS AROUND TURBULENCE WIRES,
5th European Thermal-Sciences Conference, The Netherlands, 2008

This work is based on interFoam. I think he is calling his extended solver thinterfoam as it is an extension of interfoam meaning "thermal interfoam". So you can base your settings upon this work. Have you already performed preliminary simulations looking at the fluid dynamics of a falling film? This might be the first step...

Unfortunatelly, there is no model currently implemented that accounts for the species transfer across the gas-liquid free-surface (steep concentration gradient approaching the interface + jump of species concentration due to different solubilities), as this is represented by a continuous interface approach - interface with interfacial width, smooth transition of bulk properties, etc..
I want to give some presentation on this on the next OpenFOAM workshop. The code snippet is also planned for release within OpenFOAM-extend after I validated it a bit more :rolleyes:.

thank you for your answer.

I read the paper you advise me. It looks close to my problem. In my case, we will only consider a smooth film (instead of wavy film)

what do you mean by "Have you already performed preliminary simulations looking at the fluid dynamics of a falling film? This might be the first step..." ?? I have determined simple analytical solution for the falling liquid flow. So you think I could use the interfoam solver and imposed my analytical velocity field ?

In fact, in my work, I need to evaluate a model of my own by comparison with this falling film test cases (evaluation, mass exchange coefficient, mass exchange rate, effective dispersion coefficient at large scale...)

What is the "code snippet" ? (sorry for my questions... but I am just starting with OpenFoam...)

Thank you again for helping

Hi Cyp,

You are welcome :)

Well, interFoam is based on the so called one-fluid assumption resulting in a mixture model. You might have first a look if interFoam succeeds in reproducing the right fluid dynamic behavior of a falling film (since this is a free-surface flow, large density and viscosity ratios).

Are we talking about mass transfer (evaporation/condensation) or species transfer (dilute chemical component, neglect of mass exchange)?

No problem... That is simply a piece of code.

best,

Hi!

Indeed, we are talking about mass transfer (condensation, evaporation...).

According to your remarks, interFoam does not seem to be the most suitable solver for my case.

Perhaps I should carry out a DNS (That seems closer to what I need):
- a convection-diffusion equation in the liquid phase
- a convection-diffusion equation in the gas phase
- a Henry's law at the interface

As velocity field, I use an analytical Poiseuille flow in the liquid phase.

Should I create my own solver ??

Regards,
Cyp

Hi Cyp,

Did you modelled your Falling Film? If yes I have questions for you :)

Hi Guys,

I just run into this: http://web.student.chalmers.se/group...SlidesOFW5.pdf

I dont do research on liquid film, but Im wondering why interFoam can not deal with liquid film? If I refine the mesh aside the wall, why interfoam isnot suitable for liquid film? Thanks.

Can anyone help me in simulating the heat and mass transfer in the falling liquid film over vertical surface with an air flow? (the temperature of the vertical surface is kept constant below the saturation temperature of the water)
:(