Latest Discussions - COMSOL Forums

modelling induced currents

Tue, 03 Jun 2025 18:14:54 +0000

Hello,

I am trying to find the induced current/voltage/power of a coil from the magnetic fields generated by another coil.

I am using the magnetic and electric fields interface, and I have defined my primary coil using a terminal and ground boundary condition on either end of the coil, under the magnetic insulation boundary condition.

I want to make the other coil passive and simply read out what gets induced in that coil, but I am not sure how. If I use another terminal, I need to set the voltage/power, but I don't want to excite this coil too, I just want to see what it feels from the other coil.

How could I go about doing this? Thanks.

Topology Optimization: Comsol 6.3 vs Comsol 5.6 solution issue

Tue, 03 Jun 2025 10:50:09 +0000

Hi Everyone, I am working on a Topology Optimization setup of model (that consists of two materials) that undergoes Induction Heating(Physics involved: electromagnetic heating) in two step study ( Step1: Coil Geometry analysis, Step2: Frequency-Transient Solver, the optimization is applied for step 2). At first, I was having trouble running the above topology optimization in COMSOL 5.6 as I would repeatedly get "Warning: Forward solution failed, requesting reduced step." message and I was able to solve the issue by upgrading to COMSOL 6.3 But now I am facing a new problem, I am trying to run the same study in stationary solver instead of transient solver and I am not able to perform the optimization in COMSOL 6.3 as it keeps giving me an error. I don't face this issue when I run the same study in COMSOL 5.6, so I have been trying to modify the solver config to replicate the solver configs of COMSOL 5.6 but I keep getting the error.

I would really grateful any help to solve this and please let me know if you need any further information regarding this.

Best, Ashok

P.S. Please go through this link for more context on previous issue.

COMSOL–MATLAB Livelink Export Issue

Tue, 03 Jun 2025 10:08:49 +0000

Dear all,

I am using the student version of COMSOL Multiphysics 6.3 and am encountering some issues when trying to run a COMSOL model exported as a .m file in MATLAB.

Specifically, the model (which includes heat transfer and surface-to-surface radiation in a 3D geometry) runs perfectly within COMSOL. However, when I export it as a .m file and attempt to run it in MATLAB, I encounter an error during the physics definition step, particularly when boundary selections are being set.

The error suggests that some of the boundary indices being referenced do not exist.

Java exception occurred: Exception:

com.comsol.util.exceptions.UnexpectedServerException: com.comsol.model.data.SelectionOutOfBoundsException: Illegal input vector illegal entity
number
(rethrown as com.comsol.util.exceptions.FlException)

Messages:

com.comsol.model.data.SelectionOutOfBoundsException: Illegal input vector illegal entity number

This is the incriminated matlab line that gives error but in realty this happen for any selection boundary in the code:

model.component('comp1').physics('ht').feature('hf1').selection.set([41 42 46 49 50 51 53 54 56 57 66 67 68 69 71 72 74 75 83 84 89 90 107 110 127 128 130 131 133 134 141 142 148 149 150 153]);

However, I am unable to understand what is causing the issue, as the model runs flawlessly within COMSOL. The selection indices appear to match those used in the COMSOL model and therefore should exists.

Thank you in advance to anyone who might be able to help.

Best regards, Federico

Can Magnetic Fields, mf, and Magnetic Fields Formulation, mfh, work together?

Mon, 02 Jun 2025 20:44:01 +0000

Hello, I am working on a WPT 2D-axisymmetric model, using a copper coil as primary and an HTS coil, as secondary, pick up coil. My question is if i can use the mf interface, with the coil domain for the copper coil, and the mfh interface for the secondary, HTS, superconductor, coil? Can the two interfaces work together, where the magnetic field generated from copper coil, in mf interface, can be seen in the hts coil, inducing current?

Thanks, Vitor

Adding a module

Mon, 02 Jun 2025 19:49:10 +0000

I already installed the COMSOL with the license and now want to add a module and I already added in my license but i need to install it, Should I reinstall all software again or I can added on the existing software ?

Radiation shielding using lamellar micro/nano-structured materials

Mon, 02 Jun 2025 04:21:06 +0000

I am new to using COMSOL and am currently exploring simulations to evaluate the shielding performance of lamellar or composite materials against ionising radiation, specifically X-rays and neutrons.

I would greatly appreciate any recommendations for relevant references, seminars, tutorials, or experts in this area who could provide guidance or insights.

Thank you for your time and support.

Best regards,

About: The Electromagnetic Waves, Time Explicit Interface

Sun, 01 Jun 2025 12:25:29 +0000

The below post is related to an archived discussion

[start here]

By 2025, there are still no applications or cases concerning this physical field.

Mass additionally while building geometry from topology optimized product

Sun, 01 Jun 2025 04:04:35 +0000

Hello! Please help me how to know the mass of the actual topology optimized part because after i conducted topology optimization of a product (heat sink in my case) and then import mesh from database and create the geometry, the mass/volume that i can measure from geometry of this part is more than expected. For example in one case of very low mass of 0.1kg even though topology optimization was conducted successfully the end mass was showing more than 0.1 kg whereas I kept the constraint to keep only 70% of the original mass and even mass was removed from the geometry. Please let me know how we can avoid the thresholding error that adds more mass while creating the geometry of the topology optimized part. I am using the "measure" from geometry to know the volume of the product and multiplying it with density to know the mass.

Angle of incident laser

Sat, 31 May 2025 10:46:32 +0000

Hi everyone, I'm beginner in simulation with COMSOL software. I'm very curious in someone's 2015 article about deposited beam power on heat transfer in solid, they filled in 3 parameters about beam origin point, beam orientation but currently my COMSOL software can only change the z parameter of that. So can someone guide me in detail how to use this, because in the article I followed it used that equation?

Long Simulation Time for Time-Dependent Solver

Sat, 31 May 2025 04:03:31 +0000

Hi,

I am modeling an electromagnet with DC input at a constant voltage with the aim to understand the time-dependent changes in the conductivity, flux density, temperature and pull force of the equipment.

The target cycle time is 0-24 hours with steps of 1 hour. The core is soft iron with a CRGO block domain at its center.

I am unable to attach the .mph file since it is currently still running.

The time-solver is progressing time in "seconds" and not "hours" and the simulation for every 5 seconds is taking 30 seconds in real time.

The same applies for studies without CRGO that I have done for 0-8 hour results which have spanned for 12-14 hours in real time.

I need all the results mentioned before, but I need to understand how I can bring down the simulation time drastically since the real time consumed is too long.

Thank you.

How to Simulate Series-Parallel Thermoelectric Generator in COMSOL?

Fri, 30 May 2025 13:53:02 +0000

I need to simulate an electrical circuit where Peltier cells operate as generators using the Seebeck effect. I would like to connect three cells in series and then place them in parallel with another set of three cells, also connected in series. How can I set up this kind of configuration in COMSOL? Thanks a lot for your help!

Radiative Cooling of a Cube in Vacuum (Satellite Simulation)

Fri, 30 May 2025 13:48:09 +0000

I’m having trouble setting up radiation physics in vacuum. Specifically, I have an aluminum cube representing a satellite in space, initially at a temperature of 393 K. It needs to cool down by radiating heat to the surroundings, which are at 93 K. How can I set this up? Thank you!

temperature rise, Electromagnetic Heating

Fri, 30 May 2025 09:58:38 +0000

Hello, I'd like to consult about an issue I'm encountering in my simulations. I'm performing multiphysics coupling calculations using the RF and Bioheat Transfer modules. In 2D models analyzing antenna radiation effects on human tissue across different frequencies, both SAR and temperature rise vary with frequency as expected. However, when applying identical modeling steps and settings to 3D simulations, only SAR changes with frequency while temperature rise remains constant - despite modifying material parameters for each frequency. Could you please advise what might cause this discrepancy and how to resolve it? I deeply appreciate your assistance.

How to excite an HTS coil with current?

Thu, 29 May 2025 14:25:50 +0000

Hello, i am learning to use COMSOL, and i wanted to know how i can excite a superconducting HTS coil with a DC current. I started to learn with a regular copper coil, using Magnetic Fields module, mf, where i can use the coil domain, defining there the turns, and the current excitation. Now i wanted to try with an HTS coil, now represented with an homogeneous bulk of hts tape, with different turns. For this I am using the Magnetic Fields formulation, H formulation, mfh. Using the Farady's Law domain for the hts, where i define the power law for the non linear resistivity. My question is, using this module how can i excite this coil with a current, for a stationary study? And for future frequency domain studies, is it possible to connect to an electrical circuit? Like with the coil domain, from mf?

Thanks, Vitor

Study inside Study

Thu, 29 May 2025 01:36:18 +0000

Hi everyone, I need some help with a multiphysics simulation in COMSOL. I'm working on a model that involves two main studies:

-A time-dependent study, where certain material properties (permittivity and conductivity) evolve over time according to a time-dependent variable.

-A frequency domain study, where I want to evaluate the capacitance of the system based on the state of the material at each time step from the time-dependent study.

My goal is to: Run a time-dependent simulation (e.g., from 0 to 6000 hours, with 1000-hour intervals). At each time step, perform a frequency-domain analysis (using a fixed excitation frequency). Extract the capacitance at a specific point in the excitation cycle (e.g., the peak of a square wave).

However, I'm running into issues: The material properties used in the frequency domain study seem to stay fixed rather than update based on the time-dependent solution. As a result, the capacitance result doesn’t change between time steps. I tried using the “Values of variables not solved for” field to specify the correct times, but I get errors like "parameter mismatch" or the solver just doesn't progress.

My question: How can I configure COMSOL so that the frequency domain study is evaluated at each time step of the time-dependent study, using the updated material properties from that time?

Thanks in advance for any tips!

High-Pressure Hydrogen Flow Modeling

Wed, 28 May 2025 13:29:16 +0000

Hello everyone,

I’m new to COMSOL and would appreciate some guidance. I want to model the flow of high-pressure hydrogen through a pipe and valve. Specifically, I’m interested in understanding how the pressure affects the valves and bends in the pipe, and how the temperature and pressure change throughout the flow.

Could anyone guide me on the best possible approach to model this in detail? Also, are there any blogs or videos you would recommend to help me understand this better?

Separating Substrate and Ground Changes S11 Significantly

Wed, 28 May 2025 10:56:10 +0000

Hey guys,

I'm working on simulating an antenna with a ground plane (green). Initially, the ground was modeled as part of the substrate, but since I want to study different ground geometries, I split them into two separate blocks: one for the substrate and another for the ground.

However, even before modifying the geometry, I'm seeing a significant difference in results. For instance, the S11 parameter shifts from -64 dB (combined model) to -23 dB (split model).

I've tried several things to resolve this, including:

Using Union, Compose, Ignore interior faces, and Merge entities

Adding a boundary layer in the mesh (but it takes ~2 hours just to generate the mesh)

None of these have solved the issue so far. Has anyone dealt with something similar? Is there a better way to replicate a layer?

Any insights would be greatly appreciated!

Integral /surface of a Transmission plot

Wed, 28 May 2025 09:49:10 +0000

Hi everyone

I am doing some calculation on some structures to measure transmission. I am doing a parametric sweep changing the geometry and I end up with many plots of wavelength vs Transmission from mid to long wave infrared 3-14 um.

Is there a way to do the integral of the plots (each plot individually) so I can get the surface below the plot? I want to get a single value that can give me an indication of the total transmission?

Thank you

Young's modulus calculation

Wed, 28 May 2025 01:34:48 +0000

How anyone help me how to calculate Stress, Strain and Young's modulus in graphene

COMSOL version 6.3 Update 2 is available

Tue, 27 May 2025 17:47:33 +0000

Update 2 for COMSOL software version 6.3 has been released. It brings a number of significant performance and stability improvements. Users with an on-subscription license can download the update from this link.