Resources for two-way coupling

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Hi everyone,

I am planning to implement a two way coupling between electromagnetic and fluid flow equations. This would be done by calculating Lorentz force from EM in the first step and using it as force term for fluid flow and then calculating velocity fields and geometry, and then using them to recompute Lorentz force. I should be able to iterate this for a few timesteps and track changes in magnetic fields and velocity vectors with time.

I am not sure if there is a GUI method of doing this, or should I program the loop (coupling) in the java file for the models. Also, is there any similar two-way coupling example I can use as a reference from the Application Gallery, I couldn't find any myself.

Any help for getting started with this is much appreciated.

Thank you! Maruthi


5 Replies Last Post Apr 4, 2024, 10:27 p.m. EDT
Robert Koslover Certified Consultant

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Posted: 1 month ago Mar 30, 2024, 6:46 p.m. EDT
Updated: 1 month ago Mar 30, 2024, 6:49 p.m. EDT

Sounds like a multiphysics model to me. Are you modeling magnetohydrodynamics (MHD)? There's a coupled set of magnetic and electric fields (mef) and laminar flow (spf) already available, as suggested for MHD calculations, for you to select within the AC/DC module. I suggest you take a look at that. There's also an example "magnetohydrodynamics pump" model available in the Application Library.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Sounds like a multiphysics model to me. Are you modeling magnetohydrodynamics (MHD)? There's a coupled set of magnetic and electric fields (mef) and laminar flow (spf) already available, as suggested for MHD calculations, for you to select within the AC/DC module. I suggest you take a look at that. There's also an example "magnetohydrodynamics pump" model available in the Application Library.

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Posted: 4 weeks ago Apr 1, 2024, 2:30 p.m. EDT

Yes, although the magnetohyderodynamics pump is a stationary solution.

The timescales for EM equations and fluid flow is different. I want to solve EM in frequency domain and fluid flow in time dependent. I should be able to see changing fluid velocities until a user defined termination. I don't know how to get there, for now the example is too simple to provide a time dependent coupling.

Yes, although the magnetohyderodynamics pump is a stationary solution. The timescales for EM equations and fluid flow is different. I want to solve EM in frequency domain and fluid flow in time dependent. I should be able to see changing fluid velocities until a user defined termination. I don't know how to get there, for now the example is too simple to provide a time dependent coupling.

Dave Greve Certified Consultant

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Posted: 4 weeks ago Apr 2, 2024, 2:46 p.m. EDT
Updated: 4 weeks ago Apr 2, 2024, 2:46 p.m. EDT

>

The timescales for EM equations and fluid flow is different. I want to solve EM in frequency domain and fluid flow in time dependent. I should be able to see changing fluid velocities until a user defined termination. I don't know how to get there, for now the example is too simple to provide a time dependent coupling.

You might want to look at RF heating problems, where a frequency-transient study is used to solve the magnetic problem (frequency dependent) and heating (transient).

You may not find an example that is very similar but you may find examples that will give hints on how to approach this.

> >The timescales for EM equations and fluid flow is different. I want to solve EM in frequency domain and fluid flow in time dependent. I should be able to see changing fluid velocities until a user defined termination. I don't know how to get there, for now the example is too simple to provide a time dependent coupling. You might want to look at RF heating problems, where a frequency-transient study is used to solve the magnetic problem (frequency dependent) and heating (transient). You may not find an example that is very similar but you may find examples that will give hints on how to approach this.

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Posted: 4 weeks ago Apr 3, 2024, 6:14 p.m. EDT
Updated: 4 weeks ago Apr 3, 2024, 6:14 p.m. EDT

Thank you. This helped me figure out the problem. Frequency-transient solved the issue. I am trying to add in Heat Transfer as well and I am not sure what coupling interface to use.

Currently I am doing an Electromagnetic Heating interface and coupling magnetic and heat transfer in fluids but the results seem not physically right. The blog page on "Tips and Tricks in Induction Melting" (https://www.comsol.com/blogs/tips-and-tricks-for-modeling-induction-furnaces/) suggests Induction Heating multiphysics between magnetic field and heat transfer in solids. I am not sure if this is right because although it is for modelling induction furnace I am confused as to the usage of heat transfer in solids interface. Is liquid metal still considered as a solid?

Thank you. This helped me figure out the problem. Frequency-transient solved the issue. I am trying to add in Heat Transfer as well and I am not sure what coupling interface to use. Currently I am doing an Electromagnetic Heating interface and coupling magnetic and heat transfer in fluids but the results seem not physically right. The blog page on "Tips and Tricks in Induction Melting" (https://www.comsol.com/blogs/tips-and-tricks-for-modeling-induction-furnaces/) suggests Induction Heating multiphysics between magnetic field and heat transfer in solids. I am not sure if this is right because although it is for modelling induction furnace I am confused as to the usage of heat transfer in solids interface. Is liquid metal still considered as a solid?

Robert Koslover Certified Consultant

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Posted: 4 weeks ago Apr 4, 2024, 10:27 p.m. EDT
Updated: 4 weeks ago Apr 4, 2024, 10:28 p.m. EDT

The Comsol Help system notes that there are differences in the way heat transfer is represented in the "solids" vs. "fluids" representations. For solids, "the temperature equation defined in solid domains corresponds to the differential form of the Fourier’s law that may contain additional contributions like heat sources," while for liquids, "the temperature equation defined in fluid domains corresponds to the convection-diffusion equation that may contain additional contributions like heat sources." Fortunately, you can find articles available on the internet where various authors discuss their use of heat transfer equations in modeling liquid metals, including in batteries and MHD applications, for example. I suggest you review those carefully and select the approach most appropriate to your particular physical regime of interest. This software provides a wonderful toolbox, but you are the mechanic.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
The Comsol Help system notes that there are differences in the way heat transfer is represented in the "solids" vs. "fluids" representations. For solids, "the temperature equation defined in solid domains corresponds to the differential form of the *Fourier’s law* that may contain additional contributions like heat sources," while for liquids, "the temperature equation defined in fluid domains corresponds to the *convection-diffusion equation* that may contain additional contributions like heat sources." Fortunately, you can find articles available on the internet where various authors discuss their use of heat transfer equations in modeling liquid metals, including in batteries and MHD applications, for example. I suggest you review those carefully and select the approach most appropriate to your particular physical regime of interest. This software provides a wonderful toolbox, but *you* are the mechanic.

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