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Using matlab function in comsol model

December 14, 2015, 7:05 am
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Hi. I do need help with using m-function in comsol 5.1. after all procedures decribed in tutorials(define function, adding path to m-function i need) comsol cant open matlab even to plot function. comsol shows error:
Can not start Matlab
- Library: csmatlab.dll
Error in multiphysics compilation.
I do sth wrong?
Could sbd who has expirience in such a problems explain where mistake is and what sequence of actions should i execute to succeed.
P.S. I dont need Comsol_with_matlab to use external m-function just to transform some results from comsol, do i?
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About the Comsol with Matlab

January 29, 2016, 11:53 pm
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Hi, everyone
When I am trying to plot a function, and an error is occurred : Failure loading MATLAB libraries. This model requires that MATLAB is available. - File: csmatlab.dll - Function: Sigma_G.

I am new to comsol with matbal, and how can I solver the problem?
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Using data from Matlab

February 29, 2016, 1:33 pm
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Dear all Comsol users,

To make the question simple, a heat transfer model is set up in 2-D, and every step, I want to calculate the heat source term in Matlab (which will be a 2-D matrix), then send this heat source term back to Comsol.

Currently, from what I found online, the most viable way seems to be setting up a interpolation function. But my concern is that, for a 2-D problem, the interpolation function in Comsol seems to require the data source to be from 'file' instead of table (for 'table' I can set it in Matlab code). This means that I need to save this heat source term matrix from Matlab to hard drive, then read it again in Comsol every step. Will this be very slow? Or is there a better way to do this?

Thanks!
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installation error

March 18, 2016, 12:04 pm
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Hello,

We are trying to install COMSOL 5.2 on our linux cluster, and get the following fatal FPE. The system is
Red Hat Enterprise Linux Server release 6.2 (Santiago)
vmlinuz-2.6.32-220.el6.x86_64
redhat-lsb-4.0-3.el6.x86_64
glibc-2.12-1.166.el6_7.7.i686
glib2-2.22.5-6.el6.x86_64
gcc version 4.4.6 20110731 (Red Hat 4.4.6-3) (GCC)

What version of Java Runtime is required?

--thanks, Chris

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGFPE (0x8) at pc=0x0000003bd4f3bdf8, pid=8863,
tid=139950724630272 # # JRE version: Java(TM) SE Runtime Environment
(7.0_75-b13) (build 1.7.0_75-b13) # Java VM: Java HotSpot(TM) 64-Bit
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About calculation of the electron trajectory in magnetic lens(2D Axial Symmetry)

March 21, 2016, 6:34 am
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Hello,
I am a beginner of COMSOL.

I want to calculate the electron trajectory in magnetic lens(2D Axial Symmetry).
I can calculate the magnetic flux density.
Then I try to calculate the trajectory by using Time Dependent calculation.
However, electrons do not be affected by magnetic field and just go straight.

Could you check the attached file?
Any help would be greatly appreciated.

Best Regards,
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How to get the polarization state of the reflected light?

March 21, 2016, 9:55 am
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Dear all,

I have been working on the magneto-optical effect. A linearly polarized light is reflected by a magnetized film, Cobalt film for example. The reflected light is supposed to be ellipcitally polarized. Then is it possible to get the polarization state of this ellipcitally polarized, i.e., the polarization rotation and ellipticity?

All ideas will be appreciated. Thanks in advance!

Best regards,
Xiaokun

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How to obtain a variable(x,y,t) with Matlab

March 21, 2016, 1:59 pm
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For a variable, say pressure p, is a function of x,y,t.

In Matlab, we usually have p(x,y) for pressure at any point we want to know.

However, in Comsol linked with Matlab, how can I obtain pressure at any time and anywhere?

Thanks for any help.
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Diluted species transport - singularity error

March 21, 2016, 8:24 pm
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Hi,

I am trying to model the drying of wood in a cylindrical drum with fixed wall temperature.

I keep getting an error at around 1.7 seconds into my simulation. Can anybody help me solve this issues or guide me to some examples I can look at that can help me.

Thank you,

Nadeem
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When i use...

March 21, 2016, 8:47 pm
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When i use the matlab function feature node in comsol 5.1 desk, the comsol alwarys prompt “Failure loading MATLAB libraries. This model requires that MATLAB is available.”
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Calculate the bandwidth and sensitivity of transducer with comsol

March 21, 2016, 9:22 pm
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when i simulate the performance, I don't know how to calculate the bandwidth and sensitivity of transducer, such as the equations or something else?
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Transient acoustics in a solid

March 22, 2016, 4:42 am
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Hi,

I want to model an acoustic wave in a solid (polypropylene and aluminium). I can see that I am able to use the same solid materials in the transient pressure acoustics and in Solid mechanics, so I want to ask which one do you recomend me to use.

I already did some try outs in both physics:

In the transient pressure acoustics module, the wave is generated and travels through the material undistorted.

In the solids mechanics, the wave is heavily distorted and with big oscilations.

Any of them match the lab experimentation but I believe I can fix it adding some damping, but I would like to know in which of both physics should I work on.

The source of the acoustic wave its an impulse between 1 and 5 MHz of frequency.

Kind Regards
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Eigenfrequency Analysis of a Free Cylinder

March 22, 2016, 5:33 am
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Hello!
I want to know which is the sector angle that is used in the cylinder of the application "Eigenfrequency Analysis of a Free Cylinder".
Thank you!
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corrugated horn tutorial

March 22, 2016, 6:54 am
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Hello,

I am trying to follow the corrugated horn tutorial. Once I finished entering the parameters and try to proceed to the geometry, I see that that geometry tab is disabled.
What am I missing?

Thanks
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Contact model

March 22, 2016, 1:28 pm
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Hi,

I'm new to COMSOL and would like to model a sphere in elastic material surrounding by a layer in viscoelastic material, that is pushed inside a deformable cavity. To link my sphere with the layer, what is the best to do ? A rigid connector ? What is the difference with an attachment ?
Another question is to model the contact between the sphere and the cavity. Do I have to create a contact pair ?
Thanks in advance,
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Internal error in geometry decomposition.

March 22, 2016, 2:20 pm
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Dear all,

I recently experienced quite some trouble building my geometries when they involved structures build from parametric curves. I saw a quite a bunch of related posts here and wanted to ask whether there is now some solution to it.

The error usually happens when a structure from a parametric curve (converted to solid and then extruded) is going to be combined with another object by any kind of boolean or partition operation.

The error messages that are produced look like: "Detail: Could not trace curve"
or: "Detail: Error in parameter domain topological analysis."

I attached an example file for the latter one.

So, any hints are welcome. Thank you.

Best wishes,
Hannes
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Interpolation Function Help

July 18, 2011, 10:33 am
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Good Morning,

I'm having trouble using COMSOL's interpolation function, and I was hoping someone might be able to help. I'm trying to load data from a tab-delimited text file. I've followed the instructions in the COMSOL user guide on interpolation functions, however I get the following error when I click "plot":

"Internal error in mesh initialization.
-Plot: previewplot1 (Surface)
-Function: int1"

Additionally, when I try to solve the model I get the following error message:

"-Feature: Compile Equations: Stationary (sol1/st1)
-Error: Internal error in mesh initialization."

When I disable the interpolation function, COMSOL successfully solves the model.

The input data used for the interpolation function was a velocity distribution exported from a previous solution surface. It has the following structure:

% x y z myfun1
0.005164328 0.094835672 0.2 0.098519135
0.015894103 0.087647192 0.2 0.511590803
0.015569986 0.095339275 0.2 0.22689919
0.006197193 0.083275657 0.2 0.312314232
0.005469283 0.016082383 0.2 0.2672031
0.004733427 0.004733427 0.2 0.081290304
0.012546053 0.01240331 0.2 0.43510989
0.015707096 0.004896326 0.2 0.232560416
0.027164381 0.094602393 0.2 0.368319369
etc.

A very simple flow model demonstrating the problem is attached, along with an excel version of the data I'm using. I'm a new COMSOL user, and any advice would be greatly appreciated.

Thank You!
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Urgent research problem: How to solve PDE systems( 2 PDEs 2 unknown u1,u2 coupled in 2 PDEs) in Comsol 4.0????

March 14, 2012, 8:45 pm
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1.Each PDE is composed of u1,u2.
How to set up the coupling process?

2. The spatial dependence for this problem can be reduced to 1D. du/dx
But it is a 2D rectangle.
The laplcian operator will also consider another dimension(du/dx+du/dy).
We want y dependency vanished.
How to deal with this issue?

THANK YOU VERY MUCH to get a little help.

Best Regards
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parametric sweep

April 5, 2013, 5:22 am
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hi,
can we use geometry parameter like (length, width, height) in parametric sweep, i want to see how the output changes with variation in geometry
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reservoir modelling with two phase linear poroelasticity

March 2, 2016, 5:48 am
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Hi everyone,
I have a question: is it possible to create a two-phase reservoir model in Comsol by using Subsurface flow Module (Poroelasticity)?

Thank you all

Giulia
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Moment diagram along a 3D beam

March 19, 2016, 4:11 pm
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Hi,
I am new to COMSOL and having problem with extracting moment diagram from a 3D cantilever beam under various loads. I have applied loads and moments at the free end of the beam and defined the plastic properties of the material used in the model. Accordingly, I do not want to calculate the resultant moments by using the structural analysis formula ( F*d=M), but I was hoping COMSOL could calculate the resultant moment at each section of the beam and present the moment diagram along the beam length as a result.
I have used the "probe" feature for this matter and been unsuccessful (Probe gives the reaction moment of just one section).
Any help is appreciated.
Thank you
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