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How to export data in excel format?

May 31, 2012, 10:35 am
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Hey Ivar,
I want to export my figure into excel format. and replot it in matlab. Is it possible ?
Thank you very much!!

Baofeng
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Saving probe tables in a parametric study

August 1, 2012, 1:03 pm
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Hi,

I am using several probes to plot and also write the data to a table during solving. With the new version, since we have the option to save the table in the model and as a separate file as well, I am using that option. In this way, as the model is running, the probe data are being saved to a text file.

However, when I use parametric sweep in my analysis, as it finishes running for a parameter and switches to the next one, the former probe table file is overwritten. Is there a way to save each of these probe table data for different parameters in separate files?

Thanks.
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Tolga
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export error

August 27, 2012, 6:13 pm
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Hi
I run a simulation and tried to export the results. I am getting the following error . Unknown property, property: spacevars. what does it mean?
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Stationary study of a beam immersed in water

August 29, 2012, 1:32 pm
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Hello Everyone,

I am trying to analyze stationary behavior of a single-crystal silicon cantilver beam which is immersed in water. To do this, I have used Fluid structure interaction module. I apply a body load on the beam and plot the displacement of the tip of the beam. While I could perform stationary study of the same beam using solid mechanic module (with no surrounding fluid), I am running into errors when I use FSI. I am attaching my model herewith. Please provide some guidelines as to how should I go about solving this problem.

Thanks
Sankha
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How to check mass balance?

August 30, 2012, 6:41 am
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Hi,

I was wondering if there is any way to check the mass balance in Comsol? It's kind of hard and time consuming to calculate the mass balance by hand, so does Comsol provide it for users by default?

If anyone can help me, I will really appreciate

Thanks

Simin
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How to solve a general PDE without any physical meaning?

August 31, 2012, 10:16 am
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I am a learner for COMSOL. I am trying to solve a general PDE without any physical meaning. If anyone could help me on this or show me any tutorial, I will appreciate it very much.
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structural mechanics in comsol 4.2

August 31, 2012, 1:32 pm
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Hello sir/madam,

Can i do electromechanical analysis in 4.2 version for cantilever beam type structures
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Importing the solved Soltion

August 31, 2012, 1:51 pm
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Hi,

I have solved a solution for a 3D object, I'm going to import this solution for another solver so that I could be able to use the results for the solution 1 and save running time. Is there anybody can help me in this regard?

Thanks,
Pouya
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Where is the Curl operator in the PDE physics?

August 31, 2012, 10:58 pm
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Hello,

I tried to modify the PDE from the rotating machinery physics a little and wanted to define it in the PDE physic.
The problem I have is that I can't see any curl operators in the coeficient or the general form. The original equations are:

sigma* dA/dt + curl(H) - sigma v x B = J
and
B= curl(A)

I'm sure there is a way to define both equations. Maybe I could use the diveregence operator with a matrix or something else...

Thanks in advance
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difference between segregated and fully coupled solver comsol

September 1, 2012, 9:17 am
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Hi folks,

I am trying to understand the advantages of each of these solvers, and when to use or the other.

I looked through the docs but I am left with the same doubts.

Can anyone point out the main differences and pros/cons of these solvers, and perhaps the iterative solvers, also.

Thanks.

Cheers!

R.Silva
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Heat transfer simulation result is much larger than experimental result

September 1, 2012, 8:15 pm
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I modelled the heat transfer through a hollow brick to calculate the equivalent thermal conductivity. So general heat transfer and weakly compressible Navier-Stokes modules were taken to build the model. But the simulation result is a little larger than the value obtained from experiments. The result of simulation is 0.91 w/(km), while experimental result is 0.68 w/(km).

I consider there should be some problems with my model (probably convection), but I can't find it. The simulation is successful, no error messages. So what could be the problem causing the big difference between computational result and experimental result?

Can anyone please help me?

Thanks in advance
Xiqi

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Magnetic force imposing on magnetic fluid in 3D magnetostatic field (no currents)

September 2, 2012, 1:09 am
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Hi

Everyone

I try to do with a simulation of magnetic fluid imposed on magnetic force in magnetostatic field (no

currents), but the results show that there seems to be no magnetic force on magnetic fluid.

Equations of magnetic force are expressed as:

Fx= mu0_emqa*(Mx_emqa*d(Hx_emqa,x)+My_emqa*d(Hx_emqa,y)+Mz_emqa*d(Hx_emqa,z))

Fy= mu0_emqa*(Mx_emqa*d(Hy_emqa,x)+My_emqa*d(Hy_emqa,y)+Mz_emqa*d(Hy_emqa,z))

Fz= mu0_emqa*(Mx_emqa*d(Hz_emqa,x)+My_emqa*d(Hz_emqa,y)+Mz_emqa*d(Hz_emqa,z))

I am sorry that I could find out what went wrong, and your help is highly appreciated!

Thanks!

Best wishes

Hongliang Zhou
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cut point graphics

September 2, 2012, 1:51 am
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Hi

The cut point plot in my 2D model shows the point as a huge red dot (much bigger than the domain size).

How can I reduce the size of this dot so it sits nicely inside the domain?

Thanks

David
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Creating an external Magnetic Field

September 2, 2012, 3:35 am
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Hi,
I am trying to model a superconducting wire under magnetic field. Since the design of a SC wire includes a circular variable dependency of the conductivity and the current density, I have to use PDE general form to model it. The model works nicely in 3D (attached) without the magnetic field. (Note: this file is without the solution so it is uploadable - the mesh is extremely fine so change it if you run it).

I have been trying for over a month now to apply that magnetic field. An external magnetic field seems like something impossible for COMSOL to comprehend; even when I try adding MF and current in Helmholtz coils nearby to create the field on the wire, it seems that the coupling of the H field in the MF physics and the H solution for the PDE are just not cooperating - they are not the same, and the solution, if it solves, is incorrect.

Please help me!
I need to create a A*cos(21*pi*t[1/s]) magnetic field on the wire while the current flows in it, how can I do that?

thank you very much for your time,
Shoval
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BUG in Comsol 4.3

September 2, 2012, 9:49 am
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Hello,

When we do a remeshing simulation, Comsol generates several "Deformed Configurations #" in the Mesh.
The problem is, when you redo the calculation, the number # of Deformed Configurations increases.

And it's annoying that you CAN NOT delete several unused "Deformed Configurations". (See file attached)
You can select severals configurations, but you can delete only one configuration.
It can be considered as a bug in "Remeshing". I hope Comsol staff will fix it soon.

Best regards,
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How to Introduce contact pair for cylindrical objects

September 2, 2012, 8:09 pm
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Hi everyone,

I have a problem with introducing contact pair for cylindrical object. In the model cylindrical object is overlap by another cylindrical objet. That means in the outer surface for the one object is inner surface for the othre . Both has different mechanical properties.Can I introduce that bounderies as a contact surface?

When I applied contact pair, I couldn't find destination boundaries. Can anyone explain this?

Thanks,
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question on coefficient form PDE or general form PDE

September 2, 2012, 10:57 pm
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I would like to have the following terms in coefficient form PDE or general form PDE: c*del(density) and
c*del(deldotvelocity), where c is a constant and del is the del operator. Can anyone please suggest how to do this?

Thanks,
Regards,
Manish
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Link from Comsole to Matlab

September 3, 2012, 12:33 am
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Hi,

I start the M file from Matlab to Comsole.
Starts Comsol and made same table results.
How can i put this table results to Matlab array?
Please Help.
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Resonance frequency of a piezoelectric cube

January 25, 2011, 7:45 am
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Hello,

I am trying to find the resonance frequency of a piezoelectric cube, using the Piezoelectric Devices physics of COMSOL 4.0.

The edge of the cube is 500e-9m long, and its material is Zync Oxide.

I mean to do so by two studies:

1- Frequency Domain study.

I put a voltage of 40mV on a face of the cube, the opposed face being the ground. This potential induces a deformation in the cube.
I do the study from 1e9 to 10e9 Hz with a 10e6Hz step.

I don't really know how to see the resonance... So I guess the best solution must be to plot the displacement of a corner depending on the frequency ( disp=f(freq) )?
I see something looking like a resonance frequency around 3.4GHz, but I see several other maximums at higher frequencies (8.1GHz, 8.3GHz....) , that I can't explain.

Could you tell me if it can be because of some wrong or missing parameters? or else they would be normal..

2- Eigenfrequency

I try to find eigenfrequencies around the 3.4GHz seen before (6 values by def.) , but the software seems to give me random values around this 3.4GHz frequency.
Even stranger, I will get eigenfrequencies for any eigen value I put (like 5 or 6 GHz).

Finally, sometimes I get unexplainable Complex eigenfrequencies... Do you know why?

Thanks for your time,
Regards

Michel
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Is it real to simulate Full Lightning Impulse 1,2/50 us in Comsol 4.0?

February 13, 2011, 8:15 pm
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Hi

I simulate electric fields in high-voltage switchgear.

In my models I use AC/DC Module Electrostatics (es).
If the electrode is under high potential, the boundary condition for that electrode will be Electric Potential with fixed Voltage value.
So, as a result, I get the static electric field distribution.

My aim is to simulate the influence of time dependent voltage namely Full Lightening Impulse 1,2/50 us.
It has form shown on the fig. 1 in following document:
http://eprints.soton.ac.uk/48555/1/Swaffield_ISH_conference.pdf

The duration of impulse is 50*10e-6 s. As you see it is very short.

So, here is the question.
How can I simulate the model with such time dependent voltage applied to the electrode?
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