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Vapor formation during single droplet condensation problem |
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#1 |
New Member
Luca
Join Date: May 2020
Posts: 2
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Hi everyone,
I am trying to simulate droplet condensation and coalescence on a flat surface. First of all I am trying to let a droplet grow which is already on the surface at t = 0 by water vapor condensation. The droplet and the surface beneath it have a temperature which is slightly lower than the water vapor saturation temperature. The droplet is surrounded by water vapor at saturation temperature of 373.15 K. The problem I have is that after a few time-steps the liquid fraction inside the droplet starts to decrease until there is actual water vapor formation inside the droplet. Please see the image in the attachment to have a better idea of what is happening. The water droplet has a temperature which is also below the saturation temperature, so what is happening seems quite unlogical to me. I used the following operating conditions: Operating conditions:
Thanks in advance |
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#2 |
Senior Member
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You should use a lower temperature for the fluid or else evaporation can occur. A droplet at 373.15 will evaporate, so, use a slightly lower temperature. If the water is truly at 373.15, then, vapor pressure in surrounding should be equivalent to 100% humidity. Evaporation from the inside of droplet is unphysical and incorrect since ratio of liquid density to that vapor is 2000 approx., so, bubble will explode. Secondly, a contact angle of 90 is useless since it is equivalent to default condition of non-wall adhesion. Water on copper usually makes an angle of 70.
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Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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#3 |
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Elo Nielsen
Join Date: Jun 2020
Location: Europe & USA
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Hi Luca
Did you get it to work? I am working on the subject and agree that you should set your droplet to the wall temperatur because that is how Fluent will look at the liquid phase ant let it calculate the conduction though the droplet. Regarding the used surface tension for water at ~373K you should consider incorporating the curvature of the droplet. |
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Tags |
coalescence, condensation, droplet |
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