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Time-Dependent Solver doesn't progress from 0%

Posted 2025/04/23 13:40 GMT-4 5 Replies

Berke Mert
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Hi everyone,

I'm currently working on a 3D simulation (+Magnetic Fields (mf) interface) involving an oscillating object along the z-axis, surrounded by deforming air domains. The object motion is prescribed using a sin(2pift) deformation, also for the upper and lower "air slugs" with (I hope) the correct deformation functions. The simulation needs to be in 3D since I'm gonna add asymmetric coils to the geometry to simulate induction voltages in pickup coils.

I've added a stationary solver at the beginning, and producing a stationary magnetic field plot is fine. Everything also seems fine geometrically and mesh-wise, but my time-dependent solver fails immediately with the following error:

Failed to find consistent initial values.Singular matrix.For mesh case 0 there are 72 void equations (empty rows in matrix) for the variable comp1.mf.mag1.Vc_d0...

I correctly added all the magnetic insulations boundaries, continuity bound pairs and right now I am at a loss for solutions. I would be happy if someone with experience helped me out.

Best regards.

5 Replies Last Post 2025/04/26 11:45 GMT-4
Sebastian Müller
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Posted: 6 months ago 2025/04/23 18:48 GMT-4
Updated: 6 months ago 2025/04/23 18:55 GMT-4

In Stationary the Magnet has no dependent variable Vc_d0 (Electric potential (conductors)), but in time-dependent this dependent variable variable exists. I think it needs some boundary conditions or initial Value.

You could remove this dependent variable by setting in Magnet 1 the 'Constrain for induced currents' to 'No induced currents constrain'.

Nice greetings.

In Stationary the Magnet has no dependent variable Vc_d0 (Electric potential (conductors)), but in time-dependent this dependent variable variable exists. I think it needs some boundary conditions or initial Value. You could remove this dependent variable by setting in Magnet 1 the 'Constrain for induced currents' to 'No induced currents constrain'. Nice greetings.

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Berke Mert
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Posted: 6 months ago 2025/04/26 8:03 GMT-4

Hello,

Thanks for the answer. I tried your suggestion, but it didn't solve my issue. I did however start up a fresh simulation and added a coil to the geometry and I don't get the same error message anymore, so that is solved. However, my time-dependent solver is still stuck at 0%.

I would be thankful if you take a look at it. Also have a great weekend. :)

Best regards.

Hello, Thanks for the answer. I tried your suggestion, but it didn't solve my issue. I did however start up a fresh simulation and added a coil to the geometry and I don't get the same error message anymore, so that is solved. However, my time-dependent solver is still stuck at 0%. I would be thankful if you take a look at it. Also have a great weekend. :) Best regards.

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Sebastian Müller
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Posted: 6 months ago 2025/04/26 9:45 GMT-4
Updated: 6 months ago 2025/04/26 9:47 GMT-4

I don't know what you are trying to do and sim3 is more abstract and therefore better to solve your initial problem.

Maybe you should only use time-dependent study and ramp up the desired magnetic field over time and than start your deformation oscillation.

https://www.comsol.com/support/learning-center/article/Solving-Transient-Models-That-Have-Inconsistent-Initial-Values-46461

Nice greetings

I don't know what you are trying to do and sim3 is more abstract and therefore better to solve your initial problem. Maybe you should only use time-dependent study and ramp up the desired magnetic field over time and than start your deformation oscillation. [https://www.comsol.com/support/learning-center/article/Solving-Transient-Models-That-Have-Inconsistent-Initial-Values-46461](https://www.comsol.com/support/learning-center/article/Solving-Transient-Models-That-Have-Inconsistent-Initial-Values-46461) Nice greetings
Berke Mert
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Posted: 6 months ago 2025/04/26 10:40 GMT-4

I don't know what you are trying to do and sim3 is more abstract and therefore better to solve your initial problem.

I'm doing a simulation of an induced voltage in a multi-turn coil due to a moving magnet, analogous to this tutorial I found (models.acdc.induced_voltage_moving_magnet.pdf) but with different coil symmetry hence why I need to do this simulation in 3D.

Maybe you should only use time-dependent study and ramp up the desired magnetic field over time and than start your deformation oscillation.

That should work I think, but I was underneath the impression that the stationary solver solver at the 2nd study steps, should solve for the initial values at t = 0, and from there the time dependent solver uses it. But I still get the same error.

Feature: Time-Dependent Solver 1 (sol1/t1) Failed to find consistent initial values. Out of memory in nonlinear system solution.

I'm sorry, it really is my first time doing simulations in COMSOL and I don't know what I am doing. This is actually for my Masters Thesis...

Kind regards.

>I don't know what you are trying to do and sim3 is more abstract and therefore better to solve your initial problem. I'm doing a simulation of an induced voltage in a multi-turn coil due to a moving magnet, analogous to this tutorial I found (models.acdc.induced_voltage_moving_magnet.pdf) but with different coil symmetry hence why I need to do this simulation in 3D. >Maybe you should only use time-dependent study and ramp up the desired magnetic field over time and than start your deformation oscillation. That should work I think, but I was underneath the impression that the stationary solver solver at the 2nd study steps, should solve for the initial values at t = 0, and from there the time dependent solver uses it. But I still get the same error. > Feature: Time-Dependent Solver 1 (sol1/t1) > Failed to find consistent initial values. > Out of memory in nonlinear system solution. I'm sorry, it really is my first time doing simulations in COMSOL and I don't know what I am doing. This is actually for my Masters Thesis... Kind regards.
Sebastian Müller
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Posted: 6 months ago 2025/04/26 11:45 GMT-4

Try to solve it analytically, step by step; disable deformation and continuity and try first to get that running. And then add more complexity.

Did you ever had a project-state or sim-file with less complexity, which was functionally running stationary + time-dependent?

Nice greetings

Try to solve it analytically, step by step; disable deformation and continuity and try first to get that running. And then add more complexity. Did you ever had a project-state or sim-file with less complexity, which was functionally running stationary + time-dependent? Nice greetings

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