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Thermocapillary/Marangoni Convection in CFX

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Old   May 30, 2007, 06:16
Default Thermocapillary/Marangoni Convection in CFX
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Seamus
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Hi, I'm trying to simulate the Marangoni convection caused by the presence of a bubble situated on a heated surface, but I'm having many problems. Firstly, how should I try to model this? Should I use two domains, one for air and one for my liquid, or should I represent the bubble by a volume fraction? I need to specify a fluid pair to have the surface tension option become available, but how can you specify a varying surface tension (one that varies with temperature)? I have tied a simple linear variance, but get an error stating I need some prefix for phase or particle.

Any help will be greatly appreciated,

Seamus
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Old   May 30, 2007, 06:33
Default Re: Thermocapillary/Marangoni Convection in CFX
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Phil
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Have you successfully validated a bubble free maragoni convection simulation?
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Old   May 30, 2007, 07:10
Default Re: Thermocapillary/Marangoni Convection in CFX
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Seamus
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Do you mean a free-surface model? I have not been able to specify a varying surface tension coefficient, so I can't include Marangoni forces,
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Old   May 30, 2007, 08:03
Default Re: Thermocapillary/Marangoni Convection in CFX
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Gert-Jan
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I should use one domain and a volume fraction for the bubble. However, I doubt if CFX can do the job. You need to know that surface tension is implemented explicitly and that you need a very fine mesh. Therefore you will need a lot of iterations and a very small timestep.

Perhaps you could consider Fluent or Star CD with a VOF method. Or an academic tool specifically created for this type of problem?

Good luck, Gert-Jan

www.bunova.nl

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Old   May 30, 2007, 10:15
Default Re: Thermocapillary/Marangoni Convection in CFX
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Joe
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I dont think CFX even has a facility for varying the ST coef.
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Old   May 30, 2007, 10:19
Default Re: Thermocapillary/Marangoni Convection in CFX
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Seamus
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In the modelling notes it says the Marangoni force will be automatically included if the surface tension is variable. I have asked for technical support from CFX but am yet to get any feedback.
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Old   May 30, 2007, 20:38
Default Re: Thermocapillary/Marangoni Convection in CFX
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Phil
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Have you successfully validated a bubble free maragoni convection simulation?
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