Latest Discussions - COMSOL Forums

Output in the result section

Wed, 24 Apr 2024 14:57:00 +0000

Hello Friends, I have a question. I would be grateful if anyone could help me I want to get an output, but I encountered a problem and I don't know how it is... In the data set section, I defined the maximum and minimum values and connected these two using join according to the formula I had (i.e. take the difference between the maximum and minimum temperature, divide it by the maximum value and give the percentage (data1-data2) )/data1*100 )) But I don't know how to get this output and show it now I would be grateful if any of my friends know how to guide me step by step. Thank you

Cohesive Zone Modeling only mode I

Wed, 24 Apr 2024 03:34:21 +0000

Hello,

I am modeling the connection of two objects using CZM (Cohesive Zone Modeling). I only want to utilize Mode I (tension) instead of Mixed Mode. Does anyone have any suggestions or tips?

Thank you.

heat transfer time transient analysis results are not smooth.

Wed, 24 Apr 2024 01:52:09 +0000

hello.

I am using COMSOL to perform a time dependent analysis and I am facing a situation where the resulting values over time do not converge (smooth continuous values).

The analysis is to calculate the temperature through Joule heating in a simple structure and I need to get a continuous and smooth value with respect to time. Even with a very small time interval, a few microseconds, the calculation shows a discontinuous change in slope at certain points as follows.

Is there any way to prevent this from happening with the time dependent solver option?

Thanks.

i uploaded (mash-deleted) model file. and you may check the graph image of transient temperature image from : ,,,

https://drive.google.com/file/d/1-1vwWjPE7z24-BxKagzqldwba9j11e3r/view?usp=sharing

,,,,

https://drive.google.com/file/d/1IhpdtN4fqCT-1m8jhsnLi8Z9ysAX_iRD/view?usp=sharing

Failed to find a solution

Tue, 23 Apr 2024 21:42:31 +0000

Hello Comsol,

I am trying to compute a model in electromagnetic waves, frequency domain. So, I have to find out two results, one with time modulation and other with without time modulation. When I simulated for without time modulation, I got the correct result and simulation working well. But, when I added time modulated equation in variables definition, I started getting errors. Initially, I got an error that the model is not converging, after I increased the number to iterations but as soon as I did that I get stuck in new error of singular matrix and returned is not converged. not all parameter steps returned.

I am attatching the model file with this message. Please let me know how can I reslove this issue.

Coupling Physics

Tue, 23 Apr 2024 16:58:13 +0000

Hi everyone,

How to couple the heat transfer in solids with the heat transfer in Porous media, as there are no options of multiphysic coupling. The interface between them is deined in the thermal insulation, however I want to simulate the heat transfer through this contact. I thought to define a heat source at the boundaries but I do not want to define a specific value, as I need to define the heat transfer from and to the heat transfer in solid in different scineraios.

If you have an idea, just say it. Thanks for your support

gear pumps

Tue, 23 Apr 2024 12:54:53 +0000

I am looking for anyone to share their experience with emulating gear pumps in COMSOL. I am looking for feedback on the modules used, the problem setup including. Boundary conditions, and solver configuration.

Coupling the Deformed Geometry (dg) interface with the Laminar Flow interface

Tue, 23 Apr 2024 11:01:36 +0000

Hi Could you please suggest a way for me of how to couple the Deformed Geometry (dg) interface with the Laminar Flow interface in 3D model?

Transient Simulation in COMSOL

Tue, 23 Apr 2024 10:35:08 +0000

Hello,

Is it possible to the transient simulation in COMSOL just by changing the source signal with different period? Without using the "Events" could we do transient?

Challenge: I am getting same rise and fall time for three different material in a single device. Lets's say in Silicon on Insulator, I am getting same transient effect for silicon as well as silicon dioxide.

Thanks

Phase initialization

Tue, 23 Apr 2024 01:22:04 +0000

Research background: My model involves transient calculations of many physical fields, including level sets and laminar flow. When using one research step for simultaneous calculation, the calculation step size is particularly small and slow. So I want to first calculate the remaining physical fields, and then import the results of each time step calculation into the horizontal set and laminar flow for calculation. Current issue: If the solution inherited from the previous research step is used to solve the transient, it will prompt that there is no inheritance initialization, resulting in non conservation of volume. If the phase initialization inherits the previous solution and then uses transient inheritance phase initialization, only the last step is inherited. Solution: 1. May I ask how to add a PDE module in a transient to achieve phase initialization? Is this idea feasible. 2. We are currently trying to import using COMSOL with Matlab. Or is there any other way?

Heat Transfer in Sand

Mon, 22 Apr 2024 15:47:52 +0000

Hello, I have experience in modeling heat transfer in porous media, but I'm now interested in simulating heat transfer characteristics within a soil matrix. Does COMSOL offer tools specifically for modeling heat transfer in soil or sand, or should I rely on custom material settings? For example, I want to conduct a 2D simulation for heating a thin layer of sand saturated with glue. I have all required parameters, I just need help in defining that the material is sand. Thank you for your time and consideration

very small timesteps in time dependent simulation

Mon, 22 Apr 2024 14:58:27 +0000

Dear all,

I am trying to do a mesh independence test on a time dependent Alkaline Water Electrolysis 2D simulation (Similar to the application libraries model). The physics involved are Euler Euler multiphase model and secondary current distribution. The file with the coarse mesh converges very quickly, but when I refine the mesh to check the mesh independence, the free time stepping starts taking very small timesteps after a certain time, and the simulation stalls with negligible progress. If I switch off multiphase, the model converges on both the meshes.So, I believe the non-linearity introduced by the Euler Euler model is causing this issue. I tried to check the model solution at this time for any signs of unphysical results/high residuals, but did not find any reason as to why the timestep size reduce. In the logs, I can see that the NLFAIL column increments before the time steps reduce, indicating the nonlinear solver is failing at the given timestep. The model possibly has a singularity at the junction point of the electrode and the insulating wall, which causes some oscillations in the electrolyte current density and disperse phase volume fraction, but even then the model converges at some conditions of inlet velocity, mesh size etc. I cannot pinpoint the exact reason for this behaviour. I had to clear all solutions due to size restrictions, please run the simulations to check the behaviour I described. Will be really grateful for any answers/suggestions, as I am new to comsol and attempting to solve this issue since more than a month. Please let me know in case any further info on this case is required.

Best Regards Amit

Initial stress values from stationary study not working as initial conditions for time dependent study

Sat, 20 Apr 2024 16:30:46 +0000

Hello!

I am currently using the Solid Mechanics module to simulate deformation of a shell over time. I have an initial stationary step were my material is originally very rigid, followed by a time dependent study of a much less rigid material (I use a smaller Young's Modulus).

I want to use the solution of the stationary study as an initial condition for my time dependent study. For this, I am setting the 'Initial values for the variables solved for' as the solution to my stationary study. However, when I plot the Von Mises stress for the first time step of my time dependent study, I'm not getting the same result as my stationary study.

Does anyone have any insights on why this might be, or any way to solve this problem?

Thank you so much!

How to export Electric Field map to TABLE file

Sat, 20 Apr 2024 15:33:38 +0000

Dear all, I'm a newbie in COMSOL. I want to use COMSOL to simulate the electric field and export results to input for Geant4 simulation. I need the output that has the format as below. I tried many ways to export the results but could not find any way I wanted. Can anyone help me, please? Thank you in advance.

        6           6          10

1 X
2 Y
3 Z
4 BX
5 BY
6 BZ
7 BMOD/HMOD
0 [METRE] -0.05 -0.05 -0.26 1.1283e-02 -4.3297e-03 -1.6583e-02 1.2566e-06
-0.05 -0.05 -0.22 2.4980e-02 -1.1691e-02 -3.9227e-02 1.2566e-06
-0.05 -0.05 -0.18 6.0657e-02 -4.1529e-02 -1.0921e-01 1.2566e-06
-0.05 -0.05 -0.14 1.9553e-01 -1.5685e-01 -2.8907e-01 1.2566e-06

Protein binding to porous matrix

Fri, 19 Apr 2024 18:10:44 +0000

Hi! I aim to model the binding (and unbinding as well) of protein molecules to a porous hydrogel matrix. But it seems there is no available module or function in the COMSOL. I could find a surface adsorption function, but my hydrogel matrix is a 3D domain and the protein solutes are inside the matrix, so I need a volumetric binding function to model it. Could you give me any comments? Thanks!

Nonlocal effects for nanobeam

Thu, 18 Apr 2024 20:09:06 +0000

good evening everyone, has anyone ever modeled a beam hand in COMSOL? If so, how did you account for non-local effects?

wave propagation

Thu, 18 Apr 2024 17:26:26 +0000

How can i simulate wave propagation in a porous media based on the Biot's theory

Temperature & SOC dependent electrical circuit components

Thu, 18 Apr 2024 16:39:23 +0000

Hi everyone,

My idea is to couple a 0D Battery Electrical Circuit (BEC) with a 2D or 3D thermal model. For a given current profile, the BEC will generate heat, which will be used as an input for the thermal model.

The tricky part: the components (resistor, RC-couple, etc.) of the Battery Electrical Circuit should depend on the SOC and the temperature. So I want to use the output (temperature) of the thermal model as an input to the BEC to adjust the values of the circuit components. The BEC will in turn calculate the heat loss, which will be used as an input to the thermal model, and so on.

Question: Is there a way to define the electrical circuit components as SOC & temperature dependent?

Thanks for any answer!

Refractive index of PML

Thu, 18 Apr 2024 12:34:50 +0000

Hi, In the mode analysis of optical fibers, the Perfectly Matched Layer (PML) is used as a boundary condition. Generally, the cladding layer of the fiber serves as the PML, and its effective refractive index is set to be the same as or slightly larger than that of the core material. This results in the effective refractive index of the designated PML being a constant real value rather than a complex-valued function of radial coordinates. For a cylindrical-shaped PML, its refractive index should ideally be a complex-valued function of radial coordinates. How should this simulation setup be understood, and how can the effectiveness of this method be explained? Your assistance is greatly appreciated.

Electromagnetic Force Distribution

Thu, 18 Apr 2024 11:15:17 +0000

I am working on an E-I electromagnet. I want to connect the forces generated by the electromagnet to a force distribution on a Solid Mechanics module to calculate the stresses on the I beam. How do I get this force distribution? I seem to only be able to get the total force generated by the electromagnet.

large deformation of cantilever - module selection

Thu, 18 Apr 2024 07:09:05 +0000

I would like to model a cantilever consisting of three layers. Of silicon, aluminum and nickel. Of which nickel will not be along the entire length of the cantilever. The force will act on the same section as the nickel. I am interested in very high deformation. With what module it is best to model this. Is Solid mechanics ok, for this task? I tried to make a larger deformation in the plate model deflected by magnet. And there were problems with it. Is solid mechanics suitable for large deformations?