Latest Discussions - COMSOL Forums

COMSOL Installation

Fri, 16 May 2025 13:07:34 +0000

Hello, I am Imrankhan from GE Vernova. We are trying to install comsol 6.3 on AWS. We have license server with in our GE network. We used 1718 port and xyz... license server used it..

Need information on installing this version . What could be the Username and our organization is GE Vernova.

Looking for your support.

Thanks, Imrankhan h

Activated carbon fiber packed bed adsorption and electrothermal desorption

Fri, 16 May 2025 08:49:17 +0000

How to simulate adsorption where both physical adsorption and chemical adsorption coexist in COMSOL?

"An unexpected error occurred"

Fri, 16 May 2025 06:39:36 +0000

Dear COMSOL Support Team,

I hope this message finds you well.

I am encountering an error while working with COMSOL Multiphysics. The software displays the following message:

"An unexpected error occurred. See the end of the log file for details."

This error appears during launching a model and it prevents me from proceeding further.

Details:

COMSOL Version: 6.2

Operating System:Windows

Log File: attached with this mail

I would appreciate your guidance in resolving this issue. Please let me know if you require additional information or files.

Thank you for your support.

Best regards,

request for trial passcode

Fri, 16 May 2025 06:37:31 +0000

hi team, i want to try comsol for my research work. Can you please give me trial passcode for implementing my work? i have applied for the same through i stem. please do the needful .

Discrepancy between 3D and simple 2D simulation in inductance calculation

Fri, 16 May 2025 06:19:33 +0000

Hi everyone,

I am using the COMSOL AC/DC module with a magnetic field (mf) physics in the frequency domain (1 kHz). I have simulated a rectangular coil in both 3D and 2D space (note the model is simple 2D, not 2D axi-symmetric) and computed its inductance values. My coil dimension is 100mm x 100 mm x 2 mm (i.e. length = 100mm, breadth = 100mm and diameter = 2mm). However, the inductance value from 2D FEA is much higher than the equivalent 3d FEA.

In 3D, I created the same rectangular loop and gave the appropriate excitation, meshing, and region and then, obtained the inductance value. The 3D FEA result matches my hardware results. Please see the attached link: https://drive.google.com/open?id=1L-9eyQ3RzHZ67-O4HqAMA9CeexfBUxfn&usp=drive_fs

In 2D, I have properly defined the out-of-plane thickness (as 100mm) and given excitation of +1v and -1v to the cross-section of each coil. The entire domain is meshed with extremely fine elements. Further, I also selected the region properly to get a constant inductance value. (For 2D, see the attached file) The results for 3D FEM is 334uH and 2D FEM is 388uH. For multiple turn coils, I am getting the same error in inductance results.

Note: For the circular coil, I have used 2D axi-symmetric and obtained the correct results. What could be the problem with simple 2D? Please help me solve this problem. I have been stuck here for a long time.

Surface Tension of Bubble in Transient Thermoviscous Acoustics Study

Thu, 15 May 2025 16:16:57 +0000

Hello,

I am modeling the oscillation of a bubble in water subjected to an acoustic wave. I have successfully performed the analysis in the frequency domain, where I define the acoustic wave using pressure acoustics and couple the boundary conditions with thermoviscous acoustics. Within the thermoviscous acoustics physics, I have defined two domains: air and water. At the air-water interface, I have incorporated surface tension, allowing me to plot the displacement and mode shapes of the bubble.

However, when transitioning to a transient study, I notice that the thermoviscous acoustics module lacks a surface tension node. My current setup includes "Pressure Acoustics, Transient" and "Thermoviscous Acoustics, Transient."

How can I incorporate surface tension into this transient study and accurately measure the transient displacement of the bubble interface?

Thanks in advance! Ali

Help with mesh matching a reference sketch in COMSOL

Thu, 15 May 2025 14:27:01 +0000

Hi everyone,

I'm new to COMSOL and need some help with the following task:

I’d like to create a mesh in my COMSOL-object (see picture) that matches the red lines shown in the sketch (see picture). Could someone kindly provide a step-by-step guide on how to achieve this?

Thanks a lot in advance!

Kind regards, Luisa

COMSOL modelling of magnetron antenna in launcher waveguide

Thu, 15 May 2025 14:07:15 +0000

Dear all,

After reading the following post, I would still have a question, please: https://www.comsol.com/forum/thread/344681/modeling-magnetron-antenna-connected-to-rectangular-waveguide

In the case I wish to model only the waveguide launcher and the magnetron antenna (the waveguide launcher whose picture has been attached in the previous post would be the furnace/resonant cavity itself where I would include some liquid to heat, small cube in my snapshot), how should I model the magnetron antenna? As far as I understood, it should be a coaxial port in the RF module, but not sure how to set the boundaries (please see attached picture, MPH file too big).

Thanks in advance,

Kind regards,

Fabio A.

Fluid movement induced by propeller

Thu, 15 May 2025 11:16:35 +0000

Dear,

I am currently simulating a simplified 3D system in which I have an open duct of water, in this duct I have a propeller which should accelerate the water from the inlet side towards the outlet side. This is a simplified system which allows me to setup the real system later on which I can then simulate and compare to practical experiments. I already made the simulation of the simplified duct by means of a stationary study with a rotating domain which resulted in the fluid to show swirls, as expected. However, this simulation was made by giving an inlet velocity to the inlet of the system. What I actually want is to make this simulation without a pre-selected in- and outlet boundary condition but make the fluid move by means of the propeller itself. I already tried several ways of doing so but none of them result in a working simulation.

Does anyone perhaps know if I am overlooking anything?

Kind regards,

Julian

Inquiry on Implementing Enthalpy-Porosity Technique in COMSOL

Thu, 15 May 2025 06:54:01 +0000

Hello,

I hope this message finds you well.

I am interested in simulating PCM (phase change material) melting using the enthalpy-porosity technique. I understand that COMSOL has a built-in apparent heat capacity model for phase change, but I would like to ask if it is possible to implement the enthalpy-porosity method in COMSOL.

If it is feasible, I would greatly appreciate any guidance, references, or examples that could help me set up this model.

Thank you in advance for your support.

Meshing issues - small gaps

Wed, 14 May 2025 21:47:19 +0000

Hi,

I am trying to mesh some coils that have small gaps between them (≈0.5mm). In reality this space will be filled with an insulator. I keep getting the following warnings with my mesh:

"Faces adjacent to a thin region" "Domain has a region that is much thinner than the specified minimum element size"

In understand its because of these gaps but not sure of the best approach to fix this issue. Any help would be appreciated.

FYI This is my first COMSOL project and I am self taught

use of additional drive for calculations

Tue, 13 May 2025 21:16:06 +0000

I read on a previous post how to use Preferences -> Files to set up an alternate drive for doing the calculations. It looks like there is some care to keep users straight. For our team, we share a floating license that is on a single machine, as is the alternate drive. How should the files names be structured to keep the different users distinct if we all make use of this machine?

Simulating 3D Water Droplet in Powder Bed

Tue, 13 May 2025 16:29:40 +0000

Hi,

I hope you're doing well.

I'm currently working on a project using COMSOL Multiphysics, and I'm still quite new to the software. The title of my project is:

"Optimizing the Binder Jetting Process by Simulating the Penetration Behavior of Binder in a Powder Bed."

I'm trying to simulate a 3D water droplet falling onto a powder bed, and while I've successfully designed the powder bed part of the model, I'm struggling with the setup for the water droplet. Specifically, I’m not sure how to model the droplet and make it interact properly with the powder bed using the appropriate physics.

I came across a couple of YouTube videos that show similar simulations:

https://www.youtube.com/watch?v=60cATi0LKng

https://www.youtube.com/watch?v=u8GMDY5EEmE

These were helpful for visual understanding, but they don’t provide the full setup details. I’ve tried several approaches but haven’t been able to get reliable results.

Could you please guide me through how to model the 3D water droplet and set up its interaction with the powder bed? Your support would really mean a lot to me, and it’s very important for the success of my project.

charge transfer on the interface of oxide and channel

Tue, 13 May 2025 05:31:41 +0000

Dear sir,

Can you teach me how to model charge transfer onto the surface of channel? I am using surface charge density but it is not working. As I want to show if some charge transfer takes place corresponding drain current increases or decreases

Simulation of Triboelectric nanogenerator for blood pressure measurement

Sun, 11 May 2025 13:30:05 +0000

The below post is related to an archived discussion

I get solid mechanics output and this solution is used for electrostatics interface to find output circuit voltage. Please suggest detailed steps to do this.

Geometry and domain for far-field calculation

Sun, 11 May 2025 09:53:47 +0000

Hi all,

I am trying to simulate a 2D rectangular grating element. What I want is to make a plot of the radiation pattern. I have defined the far-field domain as the medium surrounding the grating element (see figures). The outer layers are PMLs.

But I am not sure if this gives me the correct far-field. Is it ok for the far-field domain to not be circular/axi-symmetrical? And the boundaries, is it ok for them to not be closed?

My model is based off someone else's work, but they had defined the far-field as all the domains inside the outer PMLs . This however of course doesn't work because then the far-field medium is not homogeneous.

Variable Resistance for Deforming body

Sun, 11 May 2025 08:02:36 +0000

Hello everyone,

I am Malik, currently working on a simulation project involving measurement of resistance changes in a strain sensor. My objective is to monitor how the sensor's resistance varies with applied mechanical strain. However, during my simulation, the resistance value remains constant and does not reflect the expected variations with strain.

To briefly explain my approach, I'm using a conductive silver path on a PDMS surface. I have encountered specific challenges and would appreciate any guidance you can provide:

Initially, I used two physics interfaces: Solid Mechanics and Electric Currents. However, when attempting to couple these two physics interfaces, I didn't find the required Electromechanics option in the Multiphysics coupling node. Instead, the software suggested using Piezoelectric Effect, which doesn't align with my current research scenario.

Alternatively, I introduced the Moving Mesh interface to couple mechanical deformation with electrical properties. Unfortunately, whenever I select boundaries in the Moving Mesh, they become unavailable for selection in the Solid Mechanics interface, and vice versa. This issue prevents effective coupling between these two physics interfaces.

I kindly request your expert advice or suggestions regarding the best approach to accurately measure changing resistance in response to mechanical strain on a stretchable PDMS surface. If anyone has personal experience with a similar project or can recommend relevant examples from COMSOL's Application Gallery or elsewhere, it would be extremely helpful.

Thank you very much for your support and valuable suggestions!

Best regards, Malik

How to Model Continuous Electron Beam and Secondary Emission with Smooth Space Charge in Charged Particle Tracing?

Sat, 10 May 2025 03:21:28 +0000

Hi, I'm using the Charged Particle Tracing interface to simulate a continuous electron beam hitting a wall, where secondary electrons are emitted upon impact (should be continuous as well).

I first used “Specify current” (as in the Electron Beam Divergence Due to Self Potential example), but this results in a single pulse — secondary emission occurs only once.

Switching to “Specify release times” creates a continuous beam, but the resulting space charge density and potential become coarse and noisy, likely due to insufficient particle coverage.

How can I simulate a continuous beam with ongoing secondary emission, and ensure a smooth, nonzero space charge density along the beam path?

Any suggestions for improving accuracy or particle sampling would be appreciated. Thanks!

How to mirror or replicate quarter-tank simulation data to visualize the full tank?

Fri, 09 May 2025 17:07:01 +0000

Hi everyone,

I’m working on a simulation of a stirred tank using the model based on the modular_mixer_ke tutorial available in the Application Libraries, and for computational efficiency, I’ve only modeled a quarter of the tank geometry (1/4 symmetry). I’d like to visualize the full tank (i.e., all four quadrants) for better interpretation of flow fields, especially streamlines.

In ParaView, it’s possible to replicate the same streamline data by applying symmetry operations (e.g., Transform) to get a full tank view from a quarter model. Is there a similar approach or workaround in COMSOL to achieve this type of visualization?

I’m specifically interested in whether it’s possible to:

Reflect or replicate the results from the simulated quarter geometry to other quadrants.

Visualize the complete streamline field (or other fields) as if the full tank was simulated.

Any advice or suggestions would be greatly appreciated. Thanks in advance!!!

3D Electric Current in non conventional coil

Thu, 08 May 2025 14:41:10 +0000

Hello,

I am trying to create a 3D Time Domain current in a coil that has a non conventional shape, say a J-shape where the current enters one boundary on the J and leaves on the other. Does anyone know how to do it? I have a figure of the problem attached. I also attached the COMSOL file, created in 5.4