Modeling Condensation in water vapourair mixture
Can any one throw some light on "Modeling Condensation in vapourair mixture".. to be precise... Is their any commercial code that will solve these kind of problems ???
I would appreciate your responses Thanks Amol 
Re: Modeling Condensation in water vapourair mixt
I can reccomend this book about numerical simulation of condensation
Nonequilibrium Condensation in High Speed Gas Flows by Yu A. Ryzhov, U.G. Pirumov, V.N. Gorbunov http://www.amazon.com/exec/obidos/AS...1592623232920 If you have some commercial CFD product like FLUENT or CFDACE you can add condensation model by yourself by UDF  the simplest model consists from 4 ODE along streamline. Condensation of water wapor in mixture with air is pretty well been studied, but the main question  what you are interesting in ? Temperature levels or location of Wilson's line can be predicted by simple model, with droplets size distribution function situation is worse. 
Re: Modeling Condensation in water vapourair mixt
Amol,
If I'm not mistaken this has been looked at by some CFX people. Get in touch with their indian office for info: Mr Hari Doss AEA Technology Engineering Software 16 Jayamahal Main Road, Bangalore 560046 India Tel:+91 (80) 226 7272 Fax: +91 (80) 225 1133 Email: haridoss@vsnl.com 
Re: Modeling Condensation in water vapourair mixt
In StarCD, I have simulated the condensation by programming the nucleation and droplet growth model. The Young's nucleation model and Gyarmathy's droplet growth model are all very popular in the region of condensation. You can try them.

Re: Modeling Condensation in water vapourair mixt
Thanks Peter
I would really appreciate if you can give some more insight about how I should model this through udf.. and you guess is correct .. I want to know "droplets size distribution" Thanks again waiting for you response. Amol 
Re: Modeling Condensation in water vapourair mixt
Thanks Herve !

Re: Modeling Condensation in water vapourair mixt
Jing
I would appreciate if you can give some more info about it,, Thanks in advance.. Anant 
Re: Modeling Condensation in water vapourair mixt
The simple model of condensation is based on dividing the whole process into two separate steps  nucleation and droplet growth. It is dishonest  but in some situations it works. After it the nucleation rate is calculated by FrenkelZeldovich expression, and droplet growth  by some other expression (there are a lot of variants). In this case one has no need to calculate cluster size distribution function itself but can calculate only first 4 moments for it. So one has system from 4 ODE. This was usual approach for a long time and a lot of simulations of condensation of water vapors in turbines were done by such method, which was described in many books, but I prefer the one which I reccomended to you. The good agreement with experimental data is achived by fitting parameters. For some substances such approach works good, for other  not (LothePound paradox, etc.). For water it works. I think, 99.999% of all calculations of condensation were done for condensation of water vapors. But it also depends from two other main factors : average cooling rate between saturation point and Wilson's point and mass fraction of monomers. If cooling rate (the temperature gradient) is less than 100010000 K/sec  Frenkel's formula works. There a lot of details here. But the great disadvantage of such approach is that you don't have cluster size distribution function. If you really(!) need it  there are two approaches. If you are working with small clusters  honestly solve the system of ODE for nucleation process (I was using such approach to simulate metal cluster formation and growth for metal clusters beam generators). If you are working with large droplets  solve the system of equations for different fractions of droplets. It is hard to make more detail advise without knowledge of your problem.
About UDF. It again depends from your problem, but in many cases you can put selected model into your own code and call this code from commercial solver after each time step to recalculate heat source (result of condensation) and mixture molecular weight and enthalpy (function of P,T and cluster size distribution function). In CFDACE such approach can be realized. I have no handonexperience with FLUENT, but it is clear that situation is the same. If you have more questions  you can use my email. 
Re: Modeling Condensation in water vapourair mixt
Hi, Amol
Peter has described the nucleation and droplet growth process in detail. I just add something. For the homogeneous condesation, the classical nucleation theory is good enough. You can get the droplet size and number distribution at the nucleation line with the nucleation equation. Please check the following paper: Young, J. B., 1992. Two dimensional, nonequilibrium, wetsteam calculation for nozzles and turbine cascade. J. of Turbomachinery, Vol. 114, 569579. In the following flow passage, the droplet growth process could be simulated by the Gyarmathy's equation. Please check: Gyarmathy, G. et.al.1973. Spontaneous condenstion of steam at high pressure : First experimental results. Instn Mech. Engrs. Wet Steam 4. Paper C66/73 Conference, Univ. of Warwick. Hopefully they are helpful! Jing 
Re: Modeling Condensation in water vapourair mixt
Thanks Peter
I will definately get back to you on this. 
Re: Modeling Condensation in water vapourair mixt
Jing
Thanks a lot for those references. 
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