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How To add derivative boundary condition

Posted Sep 30, 2024, 1:51 p.m. EDT Electromagnetics Version 6.2 4 Replies

Shivam Singh
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I am working on a project in which I want to apply the derivative of Magnetic scalar potential (Vm) at the topmost and bottommost boundary of my rectangular(2D) domain . I don't know the value of Vm but I know the value of Derivative of Vm with respect to vertical axis(=y). Help me how to apply it. I am using comsol 6.2.

4 Replies Last Post Oct 2, 2024, 8:34 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 6 months ago Sep 30, 2024, 2:48 p.m. EDT

The spatial derivative of the scalar potential is the magnetic field. So you can use a magnetic flux density BC, which is readily available.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
The spatial derivative of the scalar potential is the magnetic field. So you can use a magnetic flux density BC, which is readily available.
Shivam Singh
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Posted: 6 months ago Oct 1, 2024, 11:02 p.m. EDT

The spatial derivative of the scalar potential is the magnetic field. So you can use a magnetic flux density BC, which is readily available.

Thank you sir for replying my problem. Sir, I try to simulate film boiling under the influence of magnetic field. My computational domain is 2D Rectangle in which Top most boundary condition is derivative of magnetic scalar potential (Vm) with respect to Y is -H_not and for bottommost boundary condition is derivative of magnetic scalar potential is H_not. I don't know the the initial value of magnetic scalar potential anywhere in domain. As you suggested I apply the magnetic flux density at the boundary when I try to simulate the study,it shows me error as follows: "Failed to fined consistent initial value". It is time dependent simulation as bubble formation ocuurs. I searched past 3 days regarding my problem this but I didn't find any solution. Most of tutorial of permanent magnet is using stationary and using B-H curve. Please help me to solve my problem.I would be very grateful

>The spatial derivative of the scalar potential is the magnetic field. So you can use a magnetic flux density BC, which is readily available. Thank you sir for replying my problem. Sir, I try to simulate film boiling under the influence of magnetic field. My computational domain is 2D Rectangle in which Top most boundary condition is derivative of magnetic scalar potential (Vm) with respect to Y is -H_not and for bottommost boundary condition is derivative of magnetic scalar potential is H_not. I don't know the the initial value of magnetic scalar potential anywhere in domain. As you suggested I apply the magnetic flux density at the boundary when I try to simulate the study,it shows me error as follows: "Failed to fined consistent initial value". It is time dependent simulation as bubble formation ocuurs. I searched past 3 days regarding my problem this but I didn't find any solution. Most of tutorial of permanent magnet is using stationary and using B-H curve. Please help me to solve my problem.I would be very grateful
Edgar J. Kaiser Certified Consultant
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Posted: 6 months ago Oct 2, 2024, 2:03 a.m. EDT

As you solve for a potential field you need to fix a reference potential in the model. As you don't have a field in x direction I applied 'Zero Magnetic Scalar Potential' to the top boundary and it solves.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
As you solve for a potential field you need to fix a reference potential in the model. As you don't have a field in x direction I applied 'Zero Magnetic Scalar Potential' to the top boundary and it solves. Cheers Edgar
Shivam Singh
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Posted: 6 months ago Oct 2, 2024, 8:34 a.m. EDT

As you solve for a potential field you need to fix a reference potential in the model. As you don't have a field in x direction I applied 'Zero Magnetic Scalar Potential' to the top boundary and it solves.

Cheers Edgar

Thank you sir for helping me. It means I have to assign the value of scalar potential in my domain. One last question sir, Is there any way I can see the variation of "H" in my domain. I am new in COMSOL. I tried to search in internet but I didn't find. Again, Thank you for helping me.

>As you solve for a potential field you need to fix a reference potential in the model. As you don't have a field in x direction I applied 'Zero Magnetic Scalar Potential' to the top boundary and it solves. > >Cheers >Edgar Thank you sir for helping me. It means I have to assign the value of scalar potential in my domain. One last question sir, Is there any way I can see the variation of "H" in my domain. I am new in COMSOL. I tried to search in internet but I didn't find. Again, Thank you for helping me.

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