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2D Marangoni Effect due to Evaporation of Solute

Posted Dec 13, 2013, 11:26 p.m. EST 3 Replies

Sathish Akella
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Dear Community,

I am trying to solve Marangoni effect due to evaporation of solute. I have closely followed the model example in which the Marangoni effect is due to the thermal gradients.

Here is what I would like to know.

1. How to define the weak term in my model? I have tried using "-test(u)*k*cx"
Also, I don't understand weak term properly :( and what do these test functions mean?
2. I think, one can also use boundary stress instead of weak term. I defined my boundary stress as "-k*cx". When I try to solve I have convergence problems. Any thoughts?

also, I really appreciate if some one can give me an intuitive understanding of weak term.

PS: k is the evaporation rate and cx is the gradient in c (i.e.) dc/dx

thanks
Sathish.
3 Replies Last Post Jun 11, 2015, 5:48 p.m. EDT
Sathish Akella
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Posted: 1 decade ago Jan 7, 2014, 4:16 a.m. EST
Dear Community,

I solved the 2D Mrangoni effect with variation in surface tension due to thermal gradients using Boundary Stress (For now, I will not use weak constraints). Note that the "diffusion of heat" and "diffusion of material" follow identical physics. But when I use "Transport of Diluted Species" instead of "Heat Transfer in Fluids", the solver fails.

Here is what the attached model does:

1. It has two studies, "Study 1" and "Study 3"
2. Study 1 solves the "Heat Transfer in Fluids" coupled with "Laminar Flow"
3. Study 3 solves the "Transport of Diluted Species" couple with "Laminar Flow"

I have adjusted the parameters such that the solution when solved ONLY for "Heat Transfer in Fluids" is identical with the solution when solved ONLY for "Transport of Diluted Species". This is a way to check that the solution to diffusion equation is same no matter which module you use.

thanks in advance,
Sathish.

Dear Community, I solved the 2D Mrangoni effect with variation in surface tension due to thermal gradients using Boundary Stress (For now, I will not use weak constraints). Note that the "diffusion of heat" and "diffusion of material" follow identical physics. But when I use "Transport of Diluted Species" instead of "Heat Transfer in Fluids", the solver fails. Here is what the attached model does: 1. It has two studies, "Study 1" and "Study 3" 2. Study 1 solves the "Heat Transfer in Fluids" coupled with "Laminar Flow" 3. Study 3 solves the "Transport of Diluted Species" couple with "Laminar Flow" I have adjusted the parameters such that the solution when solved ONLY for "Heat Transfer in Fluids" is identical with the solution when solved ONLY for "Transport of Diluted Species". This is a way to check that the solution to diffusion equation is same no matter which module you use. thanks in advance, Sathish.

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Susant Patra
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Posted: 10 years ago Jan 5, 2015, 8:09 p.m. EST
Hi Sathish,

I tried to run example_v1 in comsol 5.0. unfortunately it did not converge (both study 1 and study 3). Do you have an updated version of the problem?

Thanks for your help.

Regards,
Susant
Hi Sathish, I tried to run example_v1 in comsol 5.0. unfortunately it did not converge (both study 1 and study 3). Do you have an updated version of the problem? Thanks for your help. Regards, Susant
Michael
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Posted: 9 years ago Jun 11, 2015, 5:48 p.m. EDT
In the attached image is the answer for the test function. hope helps
In the attached image is the answer for the test function. hope helps

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