Latest Discussions - COMSOL Forums

Magnetic Field Simulation : Difference in Inductance Values

Fri, 21 Mar 2025 06:56:09 +0000

Hi All, I have modeled a Transformer 2D as shown in below image in COMSOL AC/DC Module to find the leakage inductance.

I'm using version COMSOL Multiphysics 6.0 (Build: 405). I have used homogenized, numeric, coil group feature for the windings. The LV_a and LV_b constitutes one coil group for the LV winding, with LV_b having reversed current direction. Similarly, the HV_a and HV_b constitutes one coil group of HV Winding (having opposite current direction than LV winding). The LV winding is applied with 5V and HV winding short-circuited (0V). For a Magnetic Field physics study with frequency of 20kHz, the simulation results are as follows:

LV Coil current (A) : 0.037315-4.3362i
LV Coil inductance (H): 9.1752E-06
LV Coil concatenated flux (Wb): 0.00000015255-0.000039787i
Total magnetic energy (J): 0.000043133

Now, as per the above results, the LV coil inductance calculated by using the formula,

[L = 2*Total Magnetic Energy / (LV Coil Current)^2]

is 4.587E-06, which is exactly half of the inductance value in the COMSOL results shown above.

So, which value of LV Coil Inductance is correct? And why is the difference? Can someone through some light on the above issue please?

Heat a block between parallel copper plate

Thu, 20 Mar 2025 22:45:06 +0000

Hello experts,

I am trying to heat a block (bone) between parallel copper plate. The plate is 5 cm in diameter and 0.2 cm in height. The block dimension 1x1x0.2 cm. I read a research paper who solved similar problem (attached). They mentioned using EM Waves, frequency domain and heat transfer modules. For the power input 100 W for 50 ohm impedance. Peak voltage input 100 V. They also mentioned using lumped port. Which surface should I select as lump port? Should I select uniform lump port? How can I solve the problem based on your opinion? Source file attached. Thanks in advance.

Heating Cuvette in Microwave Oven

Thu, 20 Mar 2025 22:38:36 +0000

Hello everyone,

I am trying to heat a cuvette in a Microwave oven. I have set the port and power source. When I tried to run the file it shows Undefined variable. I have attached the source file. Can anyone help me solve the problem?

Discussion on the Validity of Radiation Heat Transfer Modeling Under Cloudy and Clear-Sky Conditions

Thu, 20 Mar 2025 09:15:24 +0000

Hello everyone,

I am using COMSOL to simulate radiative heat transfer and analyze the radiative performance of a sample under both cloudy and clear-sky conditions. I have obtained surface irradiance data for both cases and am conducting simulations using surface-to-surface radiation heat transfer to evaluate the effects of different atmospheric conditions.

In my model, I consider radiative counterpart temperature and external radiation source irradiance as the primary variables:

For clear-sky conditions: The radiative counterpart temperature is set to outer space at 3K. The external radiation source irradiance is taken from clear-sky surface irradiance data. For cloudy conditions: The radiative counterpart temperature is set to the cloud layer temperature. The external radiation source irradiance is taken from cloudy-sky surface irradiance data.

I have the following questions and would appreciate any insights:

Are there similar application cases that I can refer to? If so, is my modeling setup reasonable?
Since the surface irradiance already accounts for atmospheric absorption and scattering, is it appropriate to use surface-to-surface radiation heat transfer (which neglects the effects of the medium) for this simulation?
In my model, I only vary the radiative counterpart temperature and assume both the cloud layer and outer space are at an infinite distance. However, clouds are much closer to the Earth's surface than outer space. Is this assumption valid, or should I consider the finite distance of the cloud layer in my model?

Thank you for your time—I look forward to your suggestions!

How to obtain Spectral Radiant Power or Normalized Intensity Vs Wavelength Study and plot

Thu, 20 Mar 2025 08:37:48 +0000

Hi, Recently I am working on a project based on thermal emitter model and I want to observe that the "peak" power get radiated from my model (heater) in which wavelength range, more specifically i want to obtain it basically at IR range 8(um) to 10(um).

Now which procedure should I follow. I've taken Heat transfer in solids and the Surface to Surface radiation coupling as my physics model.In study I've taken Stationary study.

I am attaching a screen shoot as a reference, which i want to perform in my project.

Charged particle tracing, parameters influencing Collision number

Thu, 20 Mar 2025 06:01:41 +0000

Hi all, I have been simulating charged particle tracing through air, under the influence of both fluid flow and potential difference. I came across a problem with size of particle, so I was wondering if size of particle released matter in the collision or trajectory when collision cross section, background number density, particle mass, charge etc are already defined.

I also faced another problem were the required time step for detecting all the collisions and that of observing complete trajectory differs in large order. Which make me almost impossible to observe both in single simulation. Is there any way to solve this?

block heating between parallel plate - RF heating

Wed, 19 Mar 2025 23:49:23 +0000

Hello experts,

I am trying to heat a block (bone) between parallel copper plate. The plate is 5 cm in diameter and 0.2 cm in height. The block dimension 1x1x0.2 cm. I read a research paper who solved similar problem (attached). They mentioned using EM Waves, frequency domain and heat transfer module. For the power input 100 W for 50 ohm impedance. Peak voltage input 100 V. They also mentioned using lumped port. Should I use port or lump port? Which surface and condition should I use? Uniform lump or other lump option? At the end, how can I get the temperature changes of block based on your opinion? I am new in COMSOL, could you please put details. Thanks.

Modifying Selections with Get and Set in LiveLink for Matlab

Wed, 19 Mar 2025 13:27:47 +0000

Hello everyone,

I could retrieve information of selections with the "get" command (see following example with the model in the attachment).

model1=mphload('SupportSelectionExample1') model1 = COMSOL Model Object Name: SupportSelectionExample1.mph Tag: Model Identifier: root

model1.component.get('comp1').selection('sel16') ans = Geometry geom1: Dimension 3: Domains 4–5 Type: Explicit Tag: sel16 Operation: Explicit

However, I haven't been able to modify the setting under "Geometry" with LiveLink for Matlab. Could anybody help?

Best regards, Anton

Understanding the Density of States (DOS) in COMSOL

Wed, 19 Mar 2025 08:35:30 +0000

As far as I know that the Density of States (DOS) is a function of energy (E) referring to the number of allowed modes or states at that specific energy level. However, in COMSOL's material properties, it requires a constant value for the density of states (DOS) field.

The relation between DOS and E is the following,

My current task is to calculate the density of states (DOS) for COMSOL Simulation, given the DOS-effective-mass, , of a material. I am unsure what value to assign to in order to calculate DOS of my material.

COMSOL modelling of Wire Electrochemical machining for cutting steel sheets

Tue, 18 Mar 2025 17:54:03 +0000

I have created a 2D geometry for COMSOL simulation modeling, and I have attached the relevant files for reference. The geometry consists of two squares:

The upper square represents the electrolyte flow domain, with its inlet and outlet indicated in the attached files. The lower square represents the workpiece. Additionally, a circle within the upper square represents the wire. I need assistance with the following aspects:

I have resolved multiple errors encountered during the simulation; however, I am struggling with one final error: "Inverted Mesh Element." Despite my efforts, I have been unable to fix it.

In the simulation, I require tool movement towards the workpiece. I have attempted various solutions, but the tool movement is not occurring as expected.

Furthermore, I would appreciate feedback on whether the selected physics in the simulation are correct. If any modifications are necessary, please provide guidance. I am completely stuck on this issue and have been struggling with it for the past 20 days without success.

I request all viewers to kindly assist me in resolving these problems. I have attached screenshots of the error encountered & physics invoved in the COMSOL simulation file. A reference research paper for better understanding is "Modelling of Wire Electrochemical Micromachining (Wire-ECMM) process for anode shape prediction using finite element method" by Vyom Sharma, Ishan Srivastava, V.K. Jain, J. Ramkumar.

wall freeze conditions

Tue, 18 Mar 2025 16:28:25 +0000

Hello!

I'm using COMSOL 6.2 and working with es and charged particle tracing. I have an ionizer tube with flying ions through the volume. The surrounding environment is vacuum. The initial velocity of ions are based on thermal velocity. To analyze the beam parameters such as emittance and energy spread after the acceleration electrode I need to have a time interval of at least 250 us to allow ions exit the ionizer tube. I'm using axisymmetry for he geometry model. This time interval with short steps of 1 ns takes a very long time to compute and I decided to put different sections and divide the tube into 3 sections with short time intervals. so each section will stop ions using a freeze on the wall. Now I have one release (uniform time and density distribution) and three separate time dependent studies for each section. I am running the first study, the ions freeze on the wall, the solution is stored and used as dependent variables solved for in the next study while those not solved for are using es field solution. The second study doesn't let the frozen particles continue moving even though I modify the configuration in that step and remove the wall. I am not sure how to let the frozen particles continue moving as if there's no wall. Could you please guide me through this?

Thanks

Creating an application for submarine power cable for different configurations

Tue, 18 Mar 2025 11:52:56 +0000

Hello Folks,

Task - To create a single interface in COMSOL Application Builder for a model that can handle different configurations (2, 3, or 4 conductors, with or without insulation or screens)

So, i have planned to create a different Geometries for 2, 3 and 4 conductors and different studies and background in application builder creating a drop down menu to select the conductors and it should redirect to that specific geometry and study with the basic form which includes input, output, graphics and ribbon and ask for the following. 1) Conductor diameter 2) Insulation thickness 3) Screen thickness 4) cable diameter

Output Capacitance Inductance Impedance Attenuation

Also, i have all the formulas required for calculations.

So, I am looking for the resources or approach for this above conditions.

Thanks in advance

Humidity analysis in semiconductor module

Tue, 18 Mar 2025 06:25:38 +0000

Dear sir, I would like to know if we can analyze the behavior of transistors under different humidity conditions. Additionally, can we also check the repeatability of the transistor? And if yes then how can I proceed

Corrosion in pipelines - flow velocity

Sun, 16 Mar 2025 18:13:44 +0000

Hello! I am trying to implement the flow velocity in my corrosion model for pipelines. I am using the Tertiary Current Distribution, water-based with electroneutrality. I am using the convection section at the Electrolyte node to input the velocity field. I also have the convection check-box marked at the No Flux node. Would this be the correct way to implement the velocity?

Near field modelling

Sun, 16 Mar 2025 14:36:49 +0000

Hi, Can someone give details on how to have near field simulations for electromagnets. In the AC/DC module, I could not find the menu where we can switch between far field and near field simulations. Any help is appreciated. Rahul R

No Java Shell output from System.out.println("Hello World");

Sun, 16 Mar 2025 10:41:21 +0000

Hello, I have the windows version of COMSOL but System.out.println("Hello World"); doesn't print to Java Shell window, in contrast what is said in the Reference PDF. Do I have to redirect System.out. to Java Shell Window manually before using System.out. ??

I tried also with .flush() without success.

When using System.out.println("Hello World"); directly in JavaShellWindow-> Run it is functioning, but not from (global) method, like said above.

Nice Greetings

time averaged wall shear stress in COMSOL software

Sat, 15 Mar 2025 19:05:26 +0000

Please show me how to calculate time averaged wall shear stress in COMSOL software

Karim PhD fellow Jahingir Nagar University, Dhaka, Bangladesh

insertion loss (S21) and reflection loss (S11) of SAW acoustic delay lines (ADL)

Sat, 15 Mar 2025 04:16:56 +0000

I want to simulate SAW acoustic delay lines (ADL) by using COMSOL Multiphysics and find the insertion loss (S21) and reflection loss (S11).

I have seen research paper on "* Gigahertz Low-Loss and High Power Handling Acoustic Delay Lines Using Thin-Film Lithium-Niobate-on-Sapphire.*" and I want to find the following figure using COMSOL Multiphysics.

Fig. 3. Simulated ADL performance of 4.64 μm and LG of 10 μm. (a) Mode shape. (b) IL and RL. (c) Group delay. (d) Wideband performance

So, please give the detail step in COMSOL Multiphysics to find insertion loss (S21) and reflection loss (S11) corresponding to frequency domain and time domain study, condition for terminal and corresponding to formulas to find the IL and RL and how to find Group delay.

Maximum number of Newton iterations reached

Fri, 14 Mar 2025 19:09:11 +0000

Hello, I am having an issue with one of my COMSOL projects, getting the error "- Feature: Stationary Solver 1 (sol1/s1) Failed to find a solution. Maximum number of Newton iterations reached. Returned solution is not converged. Not all parameter steps returned." I have no idea how to fix it as im doing a project that gives only step by step instructions that don't explain how anything works or how to troubleshoot it. If anyone with more experience than myself can tell me where I am messing up it would be immensely appreciated.

acoustic pressure study ignorying losses

Fri, 14 Mar 2025 15:48:52 +0000

Hi all,

I have question, I need to perform frequency domain simulations in Acoustic pressure study and I would like to observe the acoustic pressure of the system considering the material losses and then without considering it. Is there a method to do it?