I am trying to model a two phase flow with evaporation and condensation mechanism. I have a cold water at 300 K flowing in at 90 degree to a channel of hot gas at 1700 K. Is it possible to model the bubble formation which is caused due to the evaporation of water. I am using FLUENT for the modeling purpose. The unique thing of the problem is it has two separate inlet for two different phase. I am not sure how should I proceed with the problem, should I go with mixture model or the Euler model? Or do you think I should directly model the droplets in DPM?
Thanks for your reply. VOF models are applicable when we need two fluids are immiscible or when we need to address the issue of interfacial surface between two fluids. I believe, i may have to go with mixture model or population balance module. Since the temperature of the incoming gas is high, it would be best if i consider water as droplets and then model evaporation.
Following links may be useful for you:
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CDAQFjAC&url=http%3A%2F%2Fwww.inl.gov%2Frelap5%2Frius%2Fyellowstone%2Fbasu.pdf&ei=8srHVLTqLOPJmAWkqYCQCg&usg=AFQjCNEg79cxvMz4cxyRNL7hE9kgm4X3yA&sig2=JN_cOXroCa1IYNSByH7K8Q&bvm=bv.84349003,d.dGY&cad=rja
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCsQFjAB&url=http%3A%2F%2Fdocs.lib.purdue.edu%2Fcgi%2Fviewcontent.cgi%3Farticle%3D1190%26context%3Dcoolingpubs&ei=8srHVLTqLOPJmAWkqYCQCg&usg=AFQjCNH5RYvYOVMgmsid65KYxbZmpAC7wQ&sig2=xn_Sg4mOkhn0ONrCNweM8w&bvm=bv.84349003,d.dGY&cad=rja
http://www.sciencedirect.com/science/article/pii/S0021999108001228
Dear Shailesh Konda,
1) For modeling gas liquid two phase flow, firstly you have to predict the flow pattern according to flow rates of liquid and gas to the channel. There is a general flow pattern map for gas liquid two-phase flow according to superficial liquid velocity of each phase.
2) Then, if it is stratified flow and slug flow, you should use VOF model. If it is homogenous bubbly flow or dispersed bubbly flow, you should use mixture model.
3) Here, your case is not pure gas-liquid flow without mass transfer. For your case, you want to see vaporization (evaporation) from liquid due to mixing with hot gas. For that issue, you have to consider mass transfer from liquid phase.
4) So, mixture model or VOF model, whatever you use, you have to activate mass transfer process. Then you also should know how much mass transfer rate from liquid phase.
5) Or, if the available mass transfer models are not match with your case, you should be able to create UDF to model that process.
6) Then, you can see the process of evaporation and condensation. Then, if the gas fraction is pre-known at the inlet, you may be able to analyze if there is evaporation process and how much it increases the local gas fraction in the flow.
I have as personal protocol simulate from the simplest to the complex, and in the process acquire experience with some problem. You ca use DPM, but try to solve with a simple approach and append run after run more features as DPM. In any case, the protocol of Nay Zar Aung is good to study your case. I recommend it.
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