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Rising bubble problem

Posted Jan 22, 2021, 10:54 a.m. EST Fluid & Heat, Computational Fluid Dynamics (CFD) 5 Replies

Niraj Sonule
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I am trying to simulate bubble rise problem. I want to find its center of mass and rising velocity at different time step. Please help me with this. It will be very greatfull.

Thank you.

5 Replies Last Post Jan 25, 2021, 8:58 a.m. EST
Jeff Hiller COMSOL Employee

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Posted: 4 years ago Jan 22, 2021, 11:29 a.m. EST
Updated: 4 years ago Jan 24, 2021, 12:24 p.m. EST

Hello Niraj,

This model shows how to model a rising bubble.

Best,

Jeff

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Jeff Hiller
Hello Niraj, [This model](https://www.comsol.com/model/rising-bubble-177) shows how to model a rising bubble. Best, Jeff
Niraj Sonule
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Posted: 4 years ago Jan 24, 2021, 9:02 a.m. EST

Hello Mr. Jeff, Thank you for your reply but i couldn't find any model in your reply. I am a learner. Thanks for your support.

Hello Mr. Jeff, Thank you for your reply but i couldn't find any model in your reply. I am a learner. Thanks for your support.
Jeff Hiller COMSOL Employee

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Posted: 4 years ago Jan 24, 2021, 12:24 p.m. EST

I fixed the link.

Jeff

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Jeff Hiller
I fixed the link. Jeff
Niraj Sonule
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Posted: 4 years ago Jan 24, 2021, 10:53 p.m. EST

I had read the procedure in that tutorial but there is no mention of determing the center of mass and rising velocity of bubble with respect to time, which are one of the major criterion for simulating this physics. It will be greatfull if you can tell me how to do this.

Thanking you.

Niraj

I had read the procedure in that tutorial but there is no mention of determing the center of mass and rising velocity of bubble with respect to time, which are one of the major criterion for simulating this physics. It will be greatfull if you can tell me how to do this. Thanking you. Niraj
Jeff Hiller COMSOL Employee

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Posted: 4 years ago Jan 25, 2021, 8:58 a.m. EST
Updated: 4 years ago Jan 25, 2021, 9:29 a.m. EST

Hi Niraj,

Sorry. From your initial message I had not understood that you had the model done. With your model already in place, computing the location of the center of mass will, I expect, be a relatively simpler, postprocessing, task. If it was me, I would tackle it by using nonlocal couplings of the integration type to compute the average x- and the average y-coordinate in the bubble (I'd use a boolean expression based on the value of the level set function to detect whether a point lies inside or outside of the bubble). Once you have the coordinates of this center of mass of the bubble, you can get to its x- and y-velocities by differentiation w.r.t. time.

Best,

Jeff

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Jeff Hiller
Hi Niraj, Sorry. From your initial message I had not understood that you had the model done. With your model already in place, computing the location of the center of mass will, I expect, be a relatively simpler, postprocessing, task. If it was me, I would tackle it by using nonlocal couplings of the integration type to compute the average x- and the average y-coordinate in the bubble (I'd use a boolean expression based on the value of the level set function to detect whether a point lies inside or outside of the bubble). Once you have the coordinates of this center of mass of the bubble, you can get to its x- and y-velocities by differentiation w.r.t. time. Best, Jeff

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