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Error: Numeric coil Coil 2 (coil2) not solved for. Solve it in a Coil Geometry Analysis step.

January 22, 2017, 8:22 pm
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Hi

I am trying to simulate the magnetic field in single turn coil. In coil I choosen

conductor model: Single conductor
In Geometry Analysis: Input - I have assigned one boundary

but when i simulate I am getting Numeric coil Coil 2 (coil2) not solved for. Solve it in a Coil Geometry Analysis step error.

Plz help..
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Cable model with point mass

January 23, 2017, 4:32 am
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Hello everyone,

i modelled a prestressed cable with truss element (both tried in 2D and 3D) and used the "prestressed analysis, eigenfrequency" to obtain the natural frequencies of the system.
Now i would like to add a point mass in the center point of the cable but when i add the central node the analysis doesn't work because, i think, it adds other dofs to the system.
I tried to build two diffrent polygon, to add the central point or to divide the polygon into two with the work plane but non of those work.
If i use form assembly insted of form union with the added central point, the analyis works but it doesnt take account of the punctual mass.

Any help would be appreciated.
Thanks in advice,
Erick.
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coil impedance

January 23, 2017, 6:08 am
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Hi every body,

I am a new user of COMSOL and I started to do a simulation of a nondestructive testing problem. My model is composed of a circular multiturn coil above a metal plate. an alternative current is applied to the coil, and I want to calculate the impedance of the coil.

please can anyone help me to solve my problem ?
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Selective mesh plotting

September 30, 2015, 4:52 pm
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Hi,

How do I make nice mesh visualizations like the one in the attachment? I.e.

1) How can I assign colors to different domains? I have colors added to materials, and Preferences -> Graphics and Plot Windows -> Show Material Color and Texture is checked

2) How do I filter only certain domains away -in this case air- and leave the coil and core intact?
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Modelling cavitation

October 8, 2015, 8:22 am
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Hi,

I'm new to Comsol and try to model hydrodynamic cavitation using the CFD module. Unfortunately, I don't know how to do this.

Hydrodynamic cavitation comprises the nucleation, fluid’s vaporization and growth, pulsation, if any, and collapse of bubbles which occurs in a flowing fluid as a result of a decrease and subsequent increase in its static pressure.


Are there any examples that investigate cavitation? Can anyone help me with this problem?


Best wishes, Murat
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How to project "arrow surface" in a "cut plane" in Comsol

June 9, 2016, 10:04 pm
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Hi everyone,

I did simulation of flow in a 3D geometry in COMSOL and I generated a cut plane somewhere in the geometry where I want to see the velocity vectors in that plane. In order to do that, first I used "Arrow surface" and made the velocity vectors. However, I need to have the component of the velocity vectors which is on the surface of my plane. Do you have any idea how to do that?

Thanks!
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Errors when computing the interpolation function

January 16, 2017, 10:02 pm
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Greetings, COMSOL user.

I have experiencing problems when computing a COMSOL + MATLAB code. The error that occurs (with or without MATLAB) is linked to Interpolation function #1 (int1). The error message says the following:

Messages:
The following feature has encountered a problem

The following feature has encountered a problem

The following feature has encountered a problem:

Failed to evaluate variable.
- Variable: int1
- Geometry: 1
- Domain: 1
I have right paths to the interpolation function which is a .txt file. I have two more functions, but I have no problems with them.

The .txt file I import consists of three columns:
First column is for X-coordinates and second one is for Y-coordinates. It's a 2D geometry. The third column assigns values for the cells created by (X,Y)-coordinates.

I appreciate if somebody could give some advice.

Thanks
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Can't hide geometric entities in my results

January 23, 2017, 7:14 am
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Hi!

I'm doing a heat transfer study and i need to see the results inside of my geometry. I created a second view and hide some geometric entities to see inside my study, but when i go to my results node and plot my second view, it doesn`t change anything in my plot. Does anyone know if and how this can be done?

Att, Lucas Kakihata.
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Geometry: How to combine multiple lines to form a continuous line

January 23, 2017, 8:47 am
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Hi,

I try to make a diamond shape with curved corners.

1-How can I make a curve that goes through the three points? In addition, I would like that when the three lines are combined, it will form a continuous line.

2- I don't know if I complicate my life by doing this, if it does, your suggestions will be appreciated.

Thank you
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Magnetic field measurement without electric current

January 23, 2017, 9:00 am
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Dear sir,
I want to measure the magnetic field of simple one sided magnet whose arrangement and position from the middle sketched box will be 0.5cm which is shown in file attached(magnet position is just to show its arrangement as they repel each others therefore i kept far distance from center sketch). As i am new to comsol ,i am trying making a model in solid-works and then import into comsol for analysis.But I don't understand ,how to start?
Kindly help me through this.

base Plate is aluminum.
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Internal Error in Geometry Composition

January 23, 2017, 3:39 pm
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I need a list of ALL the reasons this error can pop up. I swear I just spent 70% of my day fighting the software to get a damn Boolean Union to work.

For my specific case, I create a workplane and in the workplane I create a path. I sweep the path, then extrude the swept area. Depending on which parts I actually extrude (lots of overlapping parts once a sweep is done), I can combine them or get a message telling me to go kick rocks.

It's totally inconsistent. I will change the dimensions slightly and re-do the sweep and extrusion, and now it doesn't like what I extruded. Doing a Union of just the swept faces or the extruded parts doesn't make a difference.

If I mix and match correctly, it can work out. Unfortunately I have absolutely no clue as to which ones are the correct ones. Even if I select the same named bodies as before, it isn't guaranteed to work.

Why isn't the message more helpful? The error has to happen *somewhere* in the geometry. Can't it just say "error on Domain 3" or whatever. At least then I could narrow it down instead of rolling some dice again.
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"Reference direction" and "Normal"?

January 23, 2017, 6:25 pm
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Hi, everyone. I want to plot the polar graph and 1D graph in some 3D simulation. In the setting, there are two parameters, which are called reference direction and normal. What is the meaning about these two parameters and which direction do they point?
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Tthe material properties transition from power-to-liquid-to-solid in SLM process

January 23, 2017, 9:44 pm
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Dear all,

I'm studying the process and detail phenomenon of Selective Laser Melting (SLM) of metals.
In SLM process, there should be couple layers of meshes which stands for single layer of metal powders. A moving heat source is applied, and the temperature of metal powders rise and exceed the material melting point. The material properties switch to liquid metal. Once the heat source removed, the temperature cools down and once again the material properties changes. In this time, it will changes from liquid metal to solid metal.

Briefly, the material properties transition is:
metal powder->liquid metal->solid metal

I'm now evaluating some CAE software. Can COMSOL model the changes of material properties (ig. k, cp, rho...) in the Selective Laser Melting (SLM) process?
If the answer is yes, can anyone shortly illustrate how to do that?

Thank you in advance,
Po-Shen
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The scale in optimization

January 24, 2017, 12:45 am
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I am interested in solving problem of optimization, I'm puzzled about 'Scale' in control variables and parameters set.

I wander how 'Scale' influnets the progress of solving, and how to set this value?

I would greatly appreciate any help.

Thanks
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Convergence Problem

January 24, 2017, 2:22 am
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Hello Everyone!

A beginner of COMSOL software calls for help. Even though it is a thorough model with simple geometry, it doesn't converge.

When I add Heat Source term to the model it fails to converge if the range is selected to end around 20ms. Practically it shouldn't bring up any problems since Qgen term kicks in until 723K.

To me it feels like a solver problem. The values and material info are taken from an article meaning they are supposed to be correct.

Any ideas to solve this?

Thanks in advance.
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Superscatterer simulation

January 24, 2017, 4:15 am
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Hi, everyone.

I searched about superscatterer structure simulations for weeks but I failed to find any. That is why I decided to start a new thread.

I read a paper about superscatterer blocking structure. [1]

[1] Xudong Luo, Tao Yang, Yongwei Gu, Huanyang Chen, Hongru Ma, 'Conceal an entrance by means of superscatterer,' Applied Physics Letters 94, 223513 (2009).

It seems surface plasmon is not formed at boundaries between metamaterial and air.

Can anyone help me with this? Modifications to attached simulation file is welcomed.

Simulation files are attached in the link below.

www.comsol.com/community/exchange/493/

Thanks in advance.
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How to move a heating load in parabolic curve

January 24, 2017, 6:36 am
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Hi,
I am trying to model a heating load which is moving with a velocity along parabolic curve. can anyone suggest me how I should approach to model it?

Thank you
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divergence, rotational and cylindrical coordinate.

June 3, 2011, 1:36 am
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Dear COMSOL's users,

I have read in the Multiphysics Users Guide that:

"In practice, this means that to correctly implement equations containing the gradient, divergence, or curl in an axisymmetric geometry, you need to compensate for the missing terms related to the curvature of the coordinate system."

And a few lines below:

"Note: The axisymmetric versions of physics interfaces take the cylindrical system into
account, and no compensation is therefore needed."

So, my question is: if I use a 2D axisymmetric model, should I compensate or not the missing terms if we use divergence or rotational operator?

Thank-you very much in advance.

Best regards,
Isa
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Coupling of 2d axially symmetric geometry with 3D-T-junction

June 17, 2014, 11:24 pm
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Dear all,

I am modeling a flow simulation where I would like to couple axially symmetric tubes to a 3D T junction (pipe flow would not be an option for me as my fluid flow is a little special - I need control over its radial districution).

So I have to do the coupling from the end of a 2D-tube (radial 'line' bounday) to 3D T-junction (sphere boundary, same diameter). I just found information on extrusion coupling which is not working for my case (I guess).

Does anybody have an idea how to map this?

Best regards,

Nils
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Smoothing a pulse made with Analytic function

January 20, 2017, 11:59 am
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Hello,

I have made a sine pulse with an analytic function.
My step function goes from 0 to 1at the location of 2e-4. My analytic function is "100*(sin(2*pi*10^6*t)-step1(t[1/s])*sin(2*pi*10^6*t))" and the lower and upper limits are 0 to 0.001.

The problem is when I zoom in the graph does not look like sine wave. Please see the attached image.
If I plot the same function with the frequency of 10KHz instead of 1MHz, it looks fine.
It seems that there is a problem with the graph resolution. Does anyone have any idea how to solve this?

Thanks,
Hamed
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