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Solving the stress in extra dimensions inside 1D battery module

July 12, 2019, 1:32 am
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Hi all,

Hope you all will be fine and progressing in your research activities. I have a simple question.

I am using the lithium ion 1D battery model for full cell and doing galvanostatic discharging of the cell. In the Comsol version 5.4 ( under Porous electrode, particle intercalation node, there is an option to calculate the stress and strain). When i searched the equation view it shows me the equations for the radial and tangential stresses which are solved in extra dimension node. The extra dimension is the spherical particle defined in the porous electrode domain

My question is: Can i solve the Diffusion induced stress if I click the option of (calculate stress and strain in the particle intercalation node). If Yes then how I will be able to see the results along the particle radius means I want to make the particle radius as my x-axis and stress as y-axis Thanks and Best regards Yasir Ali

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stress analysis of a tension bar

July 12, 2019, 2:06 am
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Hi,

I am really new to COMSOL and I am getting errors that I don't know how to fix. I want to simulate a stress analysis of a tension bar made of titanium.

My COMSOL runs in german so it's a little bit pointless to show you screenshots. I have attached my file to this thread. Maybe an expert on this forum can help me out. :)

Thank you very much in advance.

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noise generated by an air flow

July 12, 2019, 3:24 am
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Hello

I want to simulate the noise generated by the air flow from a fan passing through a heat sink. I have the geometry, but I do not know what modules I need.

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Change of a lens' focal point with wavelength. Refractive index wavelength independent

July 13, 2019, 8:33 am
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Hello Everyone,

I was using a Comsol example for the focusing lens:

https://www.comsol.com/model/focusing-lens-57621

I made no changes to the model. The focal length of the lens is set to be 1000 um.

Initially, I was scanning the wavelength of the incident EM wave. The scan was done from 1 um to 9 um, see the attached pictures - there is also the equation solved by Comsol included in these pictures.

From the pictures, it is clear that the focal point of the lens is changing with the wavelength, even though the refractive index in the lens is wavelength independent - it is just artificially set to a some specific value.

I wish to ask you for a clarification of this effect, as I was not expecting it and was surprised to see it. My only explanation is that the usual "lens maker formula" (which states that if there is not wavelength dependent index of refraction, the focus should remain constant) is derived from the geometrical optics - eikonal equation, which in turn is an approximation for the wave equation for cases when the wavelength tends to zero.

In this case we are working in the MIR/NIR region, and maybe the eikonal equation is not valid anymore.

Could you please help me in understanding this issue?

Best Nemanja

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modeling the influence of roughness on impedance response of rectangular electrode

July 13, 2019, 2:22 pm
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Hi all, I am beginer for studying Comsol. I am modeling the influence of roughness on impedance response of rectangular electrode and using AC/DC module in Comsol now. I really do not know how can I set up the formula to calculate the current distribute around my electrode. I looked at up the formula the current= comp1.intop1(-ec.nj2(x+y)) for 2D problem. I am doing 3D now. Thank you very much!

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Vacuum evaporation

July 14, 2019, 8:29 am
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Hi, Is there any way to simulate how fast a cup of water is evaporating under low pressure (boiling)? I mean mailny the speed of mass change.

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Setting surface to ground

July 14, 2019, 3:09 pm
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Hello! I am totally new to COMSOL so I am sorry if this is really silly. I have a basic geometry (created in Inventor) with a cylinder which has a bifurcation at a point and right before the bifurcation I have 2 parallel plates. I want to put a potential difference on the plates (+/- 2000V, for example) and 0 V for the cylinder itself (i.e. make it ground). I shoot particles (protons for example) from one end of the tube and I adjust the potential such that after passing through the electric field created, the protons don't go straight, but they go through the bifurcation. So i already have some issues. The geometry is succesfully imported, but when I select materials, even if it is set on "All domains", in the list below it apperas just 1 and 2 (even if there should be at least 3 elements), and I think they refer just to the2 electrods, not to the tube itself. Then, when I want to select the ground (i.e. for the tube itself), when I go to selection list some surfaces appear as "not applicable", and these surfaces are exactly the one corresponding to the cylinder. So basically I can't set the cylinder to 0 potential. I know this is probably very basic and stupid, but in all the videos I found online, after they import the geometry everything works smoothly, so I am not sure what I am missing. Any help is greatly appreciated (I attached the COMSOL file with the geometry imported). Thank you!

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Is there a MPC functionality in COMSOL?

July 14, 2019, 10:52 pm
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My problem is to simulate two beams connected at an included angle. The diagram is shown below.

pic

The first beam is hinged on the ground, and the rotation is restrainted by a rotation spring with stiffness coefficient . The second beam is connected with the first beam via a pin joint and the rotation stiffness is .

In other FEM softwares, I know I can use MPC to achieve the connection between these two beams. But I didn't find a similar functionality in COMSOL. How can I simulate my problem. My goal is to investigate the effect of the included angle and spring stiffness on the natural frequencies of this system, so I want to perform a parametric study. A simple example file would be highly perfered and appreciated.

Best Regards

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How to set up a circularly polarized light source

July 15, 2019, 12:01 am
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I'm going to set up a circularly polarized light source in the 2-d model. Now I'm using the boundary condition of the port, but I don't know how to set it.So I hope to get your help

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Laplace equation, Potential Flow, Air/Hydrofoil, Kutta Condition, Lift/Drag

July 15, 2019, 1:05 am
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Dear fellow COMSOL users,

I'm using Laplace equation solver to get the potential flow(ideal flow) around a 3D air/hydro foil.

The inlet and outlet BCs are set correct, which I cross checked with compressible potential flow module in COMSOL.

However, the results show that the Kutta condition is not satisfied at the trailing edge. (This occurs the same when the compressible potential flow module is used.)

Is there a way to apply the Kutta condition in this situation?

Thank you in advance.

Best regards

Chris Joe.

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heat penetration in microwave oven domain through waveguide

July 15, 2019, 1:32 am
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The below post is related to an archived discussion

[start here]sir, As I am done with modelling for basic model (heating of water), i came across two problem 1. the study part showing no output as heating of water in jar domain(domain 2) . Even whenever i selecting the 'domain of oven'(domain 1) then 'jar containingwater'(domain 2) inside it is automatically selected. So the boundary condition on boundary of jar is automatically selected as perfectly conductor. and when i adding physic of "heat transfer in solid", after selecting the jar as my domain , its selected as thermal insulator on a same boundary of my jar.

  1. whenever i have been passing energy through waveguide , it is not been able to go into the microwave oven domain. what shold i do to sort out this problem. please guide me as im new learner to comsol. i am attaching my comsol file , please check out where i gone wrong.
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Composite material modeling

July 15, 2019, 3:40 am
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How to build composite tube model?

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solid mechanics weird results

July 15, 2019, 4:14 am
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Hi,

I am simulating a piezoelectric device. I am experiencing difficulty in understanding the stress result of the structure. The bottom layer has zero displacement boundary condition, however I see a bulge as seen in the image on the bottom layer. Could anyone help me understand what it is?

Regards,

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display the graph for a specific volume

July 15, 2019, 5:46 am
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Hello,

I made the mechanical simulation for a large volume (eg. 0<X<760, 0<Y<760, and 0<Z<80). But I want to general a 3D graph to show the mechanical deformation (strain) for a specific volume (e.g. 285<X<380, 285<Y<380, and 0<Z<80). I didn't find a way to do it. Could anyone help me with this? Thanks.

Best regards, Ronggang

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Laser cavitation

July 15, 2019, 7:10 am
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Hello ereryone, I am leaning the COMSOL to simulate laser cavitation, unfortunatly, I can not simulate the expansion and collase of bubble. Anyone have the related experience of bubble simulation?Or some learning materials or exact tutorials ? Please help me, my god. Best regard.

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Internal error callback

July 15, 2019, 9:08 am
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Hi there

when I run same case 5 times, maybe 3 times of them failed the error was** internal error callback**. It seems that COMSOL is unstable. It's not always worked or failed.

Any help will be appreciated.

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Solid-beam weld joint

July 15, 2019, 3:42 pm
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I screwed up the Comsol versioning on my previous post so I want to ask my question again, in proper context. I use Comsol 5.2a, I have a simple need to weld one end of a beam to a rigid domain. All I want is a way to specify a boundary condition where the location of beam contact on the rigid domain and the angle of beam contact relative to the local surface of the rigid domain do not change, no matter what else is going on in the simulation.

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How to draw an arc with fixed radius and across two points in MATLAB livelink for COMSOL

July 16, 2019, 1:10 am
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Hi,

I am using matlab livelink to draw a geometry. Does anyone know if there any commad to draw an arc with a specific radius and across two points?

Thanks!

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Opening/Accessing methods saved in the MPH file outside of the Application Builder

July 16, 2019, 1:29 am
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Hi, we created an App from MPH file under Windows (Application Builder is only available in Windows). This MPH file was then slightly edited under Linux, but the functionality of the App should not be exposed. Afterwards, we open the MPH file under Windows and upon clicking 'Application Builder', we get 'Unexpected error occured' with some error. By clicking second time on 'Application Builder' button, Comsol screen turns completely white and there's no way out of it other than exiting.

We're wondering if there's other way to open/access MPH file and its methods in Java/Matlab and debug the error in more detail. Thanks for any insights Peter

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how to know the meaning of phrase like ewfd.nxx or ewfd.kixx used as part of expression for variables

July 16, 2019, 1:49 am
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Hi， I find many phrases like ewfd.nxx and ewfd.kixx were used as part of expression for variables and it is hard to konw what these mean.Is there any files to search or anyway to know ? Thanks.

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