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evaporation in liquid background fluid

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Old   February 5, 2002, 13:07
Default evaporation in liquid background fluid
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Achim
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Hello STAR user,

I have to model a water-cooled object where local evaporation occurs which is followed by recondensation when the steam is convected to a colder environment. I expect only a small amount off 'gas bubbles' at the same time. Could someone outline the procedure of setting up such a model ?

regards
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Old   February 6, 2002, 05:54
Default Re: evaporation in liquid background fluid
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stephen
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Not easy, there is no facility to model boiling at the moment, although I've heard that there will be a VOF boiling model in version 3.2

You can use MODSWF to locally fudge the heat transfer coefficient to account for the thermal effect of nucleate boiling, but I'm not sure you can actually model the boiling and recondensation explicitly.

Cheers

Stephen
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Old   February 6, 2002, 20:51
Default Re: evaporation in liquid background fluid
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Achim
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thanks stephen, what you say about release 3.2 sounds promising although I don't know if there will be a 3.16, 3.16b, 3.17 etc. release in between. tweaking the htc is surely an important issue, if you have references, please let me know.

I'm a novice in the field of two phase flow but can't I use the first call to POSDAT to check wether a cell approaches its saturation pressure, flag it in a boolean array which I make accesible for DROICO by means of a common block. Then in DROICO release (liquid) droplets where appropriate to use STAR's build in model for vaporisation ? Will those droplets be limited by void fraction ?

Furthermore, what happens to a droplet when it's vaporised ? is it still there, so that I can make use of breakup and collision models for the gas bubbles or do I have to keep track on the scalar (vapour) and release new (vapour) droplets for that ?

thanks for taking the time

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