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Personalized heat source

January 4, 2013, 1:05 am
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Good morning everybody,

I am a novice in use of COMSOL, I want to simulate the propagation of heat through a material, sounds easy but my heat source is a surface defined by a matrix (every pixel is a source with its own magnitude),

I want to know if COMSOL can simulate this kind of source, and how?!
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3D Symmetry of Model

July 1, 2013, 12:41 pm
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Good afternoon all,

I am modelling two electrodes (tips facing each other) and the electric field between them. There are two Z-axis layers to each of the electrodes, measured in nanometers, whereas the width of the electrodes are measured in the hundreds of micrometers. Further, the electrode tips are half-cylinders. As you can imagine, this leads to some mesh-compiling problems (where it only compiles when the electrode width is set to a few dozen microns, instead of the desired hundreds), and I'm looking for solutions to be able to create and render a larger mesh.

The best hope to a solution (unless there are any you can recommend) seems to be symmetry, as both electrodes and the environment around them are identical.


I don't think 2D axial symmetry, extruded into 3D, would be able to suit my needs.

How would I do 3D symmetry along an axis? I've scoured the COMSOL forums, and while they are normally very helpful (thank you to everyone who takes the time to respond, you aren't just helping the OP) all the advice on symmetry is very vague and esoteric to a beginner like myself.

Thank you for your help,
Daniel
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Simulation of Domain switching in Ferroelectric thin film(BaTiO3) as a function of applied electric field using COMSOL

April 5, 2017, 5:52 am
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Hii;
I am currently working on the domain switching in BaTiO3 as a function of applied electric field(including direction). I want to do it's simulation in COMSOL. I found certain models in the literature, but don't know whether it is possible to model this in COMSOL. Can anyone help me, please?

Thanks a Lot in advance

Mishra
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Comsol with matlab error on HPC cluster

August 25, 2017, 8:59 pm
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Dear All,

I run my comsol models with matlab on HPC cluster which have CentOS Linux installed on it. I use the following command for starting Comsol server on HPC

comsol mphserver &

This command starts Comsol server successfully but when I start connecting matlab to it by the following commmand:

matlab -nodesktop -nosplash -r "mphstart; mymfile.m; exit",

there appears an error which say: "Comsol server must run before calling mphstart", while I am sure about starting Comsol server, even when I try to start Comsol with Matlab by the command:

comsol mphserver matlab

server starts and runs Matlab but a confusing java error occurred and further processing is blocked.
FYI, I use Comsol version 5.3, It is interesting to inform you that everything is OK on my laptop with Windows 7. These errors occurs when I try to perform my simulations on HPC.

Any suggestions and helps are appreciated, Thanks,
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Multi-Layer Coil Inductance Theory Vs Simulation

August 26, 2017, 3:35 am
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Hi All,

I m trying to compare the inductance value for a circular multi-layer coil inductor between:

The theory given by many online calculator (based on maxwell algorithms for most of them) : electronbunker.ca/eb/InductanceCalcML.htmlcoil32.net/online-calculators/...ultilayer-coil-calculator.htmlwww.pronine.ca/multind.htm or www.tesla-institute.com/!app/sim/acic.php all this website give really close results.

And a comsol 2D axissymetric simulation with the same parameters (coil length, number of turns, inner and outer diameter, wire gauge) using "multi-layer coil" of the AC/DC module.

I found quite big differences between theory and simulation for the inductance value (more than 40% for some exemples).

Does someone have a explanation for that difference ?

Note: the equivalent resistance value of the inductor between theory and simulation are really close.

Thanks
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problem in implementing laminar inflow as BCs in 5.2

August 26, 2017, 5:47 am
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Hello friends,

I have built a microfluidic model in COMSOL 5.2. It's a basically 2D long pipe. I tried to use 'laminar inflow -> flow rate' and 'laminar outflow -> pressure' as inlet and outlet BCs respectively. But the software failed to give an answer. Instead, if I specified pressure at both boundaries, then it succeeded to give a result. So how can I use the 'flow rate' as an inlet BC properly?
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What is the difference between pr2.Mflow and pr1.Mflow ??

August 26, 2017, 10:59 am
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Dear All;

Thank you for your attention. I want to plot the mass flow on a boundary of my model, but I encountered two different expressions about the mass flow, i.e. pr1.Mflow and pr2.Mflow. Actually, there are another two expressions for each of the expression given above, pr1.Mflow_d and pr1.Mflow_u. I am so confused about these expressions, and i have no ideas where i can get the meanings about these expressions.

Could you please share me some ideas? Any help would be highly appreciated.

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Power electronic device based Multichip thermal analysis

August 26, 2017, 11:26 am
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how to design multichip in comsol which are consits of IGBT and diode?I m new pls help me
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Different between modeling basic contact problem 2D and 3D

August 27, 2017, 1:21 am
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Hi All,

I did model a basic contact problem (cylinder &plate) in 2D, and it worked.

However, when I try the same problem but in 3D model, it doesn't work even if I used the same procedure like boundaries conditions, mesh, contact,....

The error just shows the "The relative residual (0.018) is greater than the relative tolerance" which just appears many times when I have tried many other modification to boundaries conditions.

I am quite a new Comsol user, and I have spent days to find the solution but I haven't figure out the problem.

Attachmetn is my 2D because I cant upload 3D (size is large here) , but I did the same with 3D.

I am looking for any helps.

Thank you very much

Yen





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Dielectric particle coating with nano-scale Au thin film

August 27, 2017, 5:22 am
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Dear experts,

I have a question about AC/DC module. A dielectric particle (sigma=1e-2[S/m], epsilonr=2.5) suspended in medium (sigma=0.7[mS/m], epsilonr=80) suffers from uniform electric field generated by a pair of parallel electrodes, which I attempt to simulate using Frequency Domain (10[kHz]~0.1[MHz]) in Electric Currents (ec).

Unfortunately, the error message occurs when nano-scale Au thin film (sigma=4.5e7[S/m], epsilonr=6.9) is coated onto the particle. I suspect the conductivity of Au is much more than this dielectric particle resulted in non-convergence solution. But, I wanna know how to solve this model? Please, give me some suggestion, Thank you :).
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Solid Mechanics

August 27, 2017, 5:20 pm
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How do we simulate a foam material in solid mechanics?
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simulation of piezoelectric Energy harvester

August 27, 2017, 7:36 pm
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I have been performing Eigen frequency analysis of piezo cantilever but the results i got are the sets of complex frequency (a+ib). Is there any solution for linearization of the complex frequency so that i can obtain my results in real value ? It would be grateful if someone show me a good solution.
Thank You
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About laser beam and transmission

August 27, 2017, 8:03 pm
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Can someone give me a help that I want to build a model is about a laser beam transmit through the air and the liquid finally arrive the destination, and I want to know the decrease of the energy when laser beam arrive the destination.
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simulation of piezoelectric Energy harvester

August 27, 2017, 8:39 pm
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I have been performing Eigen frequency analysis of piezo cantilever but the results i got are the sets of complex frequency (a+ib). Is there any solution for linearization of the complex frequency so that i can obtain my results in real value ? It would be grateful if someone show me a good solution.
Thank You
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Data from a cut line with Livelink Matlab

August 28, 2017, 1:23 am
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Hello,

I'm studing an optical waveguide in Comsol.
I have defined a cut line 2D to observe the electric field z-component along the width of the waveguide.
Then I have used the livelink matlab command:

mphinterp(model,{'real(ewfd.Ez)'},'dataset','cln1','Solnum','5')

to retrieve the same electric field z-component and plot the corresponding profile.
I have almost the same plot as in Comsol but there are some supplementary points that give the plot a saw tooth like profile.
If I export the data from Comsol into a file and use them to plot the field, I have the same smooth plot as in Comsol but I don't want to loose time exporting the data like this.

What are those supplementary points given by mphinterp? What is the good way to directly retrieve data from a cut line to avoid them?

Thanks in advance!
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Elastoplastic thermal stress problem

August 28, 2017, 1:30 am
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I am modelling an elastoplastic thermal stress problem of a 3D thin plate and am interested to find the maximum normal distortion in one of the boundary faces. I find that the location of the maximum distortion does not coincide with the location of the maximum temperature in the face, although not too far away. I was expecting them to coincide because of the domination of thermal stress in the problem. Can this behaviour be explained by a scientific explanation ?
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Creating your own equations

August 28, 2017, 2:31 am
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Hello.
I want to model the process of plasma-plasma sintering of powder materials, namely shrinkage in the process of sintering.
And since there are no necessary equations in the program, the question arises how to create your own model.
The equations that interest me can be found by link (scientific article).

oatao.univ-toulouse.fr/16581/7/maniere_16581.pdf
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1D Plot Color/Marker cycle

August 28, 2017, 4:15 am
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Hi

Is it possible to define a custom color/marker cycle for 1D plots?
Or to reset the color/marker cycle for each plot in the 1D plot group?

For example, using the predefined color tables to defined the color cycle?
I know I can do this with a Color Expression subnode, but it messes up the Color Legend.

Sometimes, with multiple plots in the same graph, the results can become confusing.

Any help in automating this process would be helpful.

Thanks :)
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How can I define the duty cycle and intensity in acoustic pressure module

August 28, 2017, 12:04 pm
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Hi,
I want to create an ultrasound model with 10% duty cycle (100 ms - ON and 900 ms - OFF) and intensity of 80 Watts/cm2. I have two questions:
1- How can I enter the parameter of intensity in acoustic pressure module? For example, how can I change the intensity as a variable for a parametric study?
2- How can I define the duty cycle in the study?
Thanks
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Boundary layer mesh

August 28, 2017, 1:45 pm
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Hi,

My question is simple, how can I make the boundary layer mesh curve around the corner highlighted in the attached image?

Edit: Why can't I attach the png-file? I get a "file extension error".

Best regards
Philip
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