Quantcast
Channel: Latest Discussions - COMSOL Forums
Viewing all 26527 articles
Browse latest View live
↧

Imported SolidWorks part doesn't behave correctly

February 17, 2013, 7:31 pm
$
0
0
I'm relatively new to COMSOL but I haven't had much luck finding a solution.
I had an assembly in SolidWorks made of 3 parts. I created a new SolidWorks part file which had the 3 parts mated together correctly and saved it. I imported that SolidWorks part into COMSOL. COMSOL recognized it as having 3 domains which I assigned different material properties to. I fixed the bottom and applied a load on the top. When I ran a tetrahedral static solid model test, the stress was what I expected for the top layer but it appears that it did not make it to the remaining layers. The stress on one side of the interface is a magnitude different than the other side, right at the interface. I attached a picture of this.

The nodes seem to align at the interface too. Even when I used the same mesh size for the entire model, I had the same issue. Does anyone have suggestions on a solution? I also attached my setup.
I can provide more detail and pictures if needed.

Thanks,
Jeremy
↧
Search

about helix geometry modeling

February 18, 2013, 7:37 pm
$
0
0
Hi, I am trying to model a spiraling geometry (helix-like) with a complicated cross section. Does anyone know how to do it with comsol 4.2/4.3a?

I used the build-in "helix" one but that was with a circle cross section while what I want is actally not that simple.

Thanks for any feedback!
↧
↧

Vanishing geometry in nano level

February 19, 2013, 12:07 am
$
0
0
Hi

I'm trying to plant some nano-cylinders on a larger cylindrical base of [um] dimensions. When I plant 3 cylinders on top with 200[nm] radius, everything works just fine. But if I reduce their sizes to 50[nm], only one of the wires remain. If I add another cylinder of same dimensions, the whole structure just vanishes.

I've already played around with the relative tolerance values. Currently, it's 1e-9. But nothing seems to be working. I've narrowed down the problem to 'form union' section under geometry. But I cannot figure out a solution.

Any advice is appreciated.
↧

Study 1 error

February 19, 2013, 12:41 am
$
0
0
Hello,
I want to ask some questions. I can try make an example e-core magnet design. There is an error in the Study 1 section. When I right click the Study 1 and select show default solver, an error happens : " The DAE is structurally incostistent. Variables:2 Equations:1 Error in automatic sequence generation. "
I thinking one of the reason of the error is the External I Vs. U 2 I enter only p label parameter for 3, there is no n label parameter in the example.
The other problem, in the Gauge Fixing for A-Field 1 section, there is no "Constrain variable in at least one point" check box. I can not found it. Please can somebody help me?
↧

Solid Oxide Fuel cell (SOFC) model in fuel cell and batteries section

February 19, 2013, 12:43 am
$
0
0
Dear All

I was using the solid oxide fuel cell (SOFC) model available in the COMSOL library of Batteries and Fuel cell. However in that model, I found that the user needs to input the inlet velocities at the anode and cathode respectively which remains unchanged.

In actual fuel cell the inlet velocities change depending upon the applied load. Only the respective stoichiometries (multiples of the actual consumed reactant) at anode and cathode remain constant. If anybody else has used the same fuel cell model and find this problem or if someone has used a different approach to vary the velocities, their assistance would very much be appreciated.

Regards
Abhishek Raj
↧
↧

Can't add point load to shell.

February 19, 2013, 1:47 am
$
0
0
I can't add a point load to my shell for some reason.

I've tried adding all points, and the non-corner point has (not applicable) written after it.

Please could someone help me understand why this is and maybe suggest way around it?

Thanks in advance.
↧

Heat in inductor using Induction Heating

February 19, 2013, 2:04 am
$
0
0
I'm working on a model to see the temperature in all of the parts within the inductor. Since I'm using the Induction Heating physics I have to excite the inductor using Lumped Ports. However the simulation only converges when I put one of the boundaries of the big box that surrounds the inductor to a specific temperature.

The questions I have are:

- Is the excitation correct if I want to compare the results with measurements done in real life?
- How can I get around the need to put a boundary to a fix temperature since this isn't accurate with real life?
- Are there any improvements i can do to my model for an even more accurate solution?

I'm currently using COMSOL 4.3, the model geometry is taken from the Model Library > AC/DC module > Inductive devices and coils > inductor_3d.mphbin and the meshing is a Coarse, Physics-controlled mesh.

Thank you in advance
↧

meshing big geometry

February 19, 2013, 2:43 am
$
0
0
Hi
how to divide a big geometry of 100 m length and 1-200 mm thickness into several sub geometries to enhance the mesh quality? Is there any node in comsol to do ?
↧
Search

How to turn on display of domain/boundary/point numbers (in Model Builder~Graphics Window)

February 19, 2013, 3:40 am
$
0
0
A very simple question for which I cannot seem to find an answer! ..... nor successfully managed to locate it within documentation.

In the Graphics Window within Model Builder, it is often desirable to turn on/off the display of domain, boundary and/or point numbers. This can apply most commonly to meshes, but is also useful in results display/visualisation at times (e.g. when looking at contour plot on 2d surfaces).

Whilst there is access to varying degrees of Graphics Windows functionality/manipulation, via icons which appear above the window (...the number and extent of which are contextual), there is no obvious access to a whole host of possible annotations, even if that as a minimum simply comprises turning on/off all of the domain, boundary and/or point numbers...

↧
↧

Problem assignment of material parameters (properties) in porous materials

February 19, 2013, 7:46 am
$
0
0
I am using poroelasticity module. There are porous material and fluid in the model. When I assign the properties of porous material or fluid, I need to choose which domain I should assign. The fluid and porous materials are at the same domain, because fluid exists in the void of porous materials. So after I assign the properties of the porous materials, for example, density, to a certain domain, I need to assign the properties of fluid to the same domain. But the question is that after I assign the properties of fluid to this domain, the assignment of properties of porous materials will be overridden by the properties of fluid.

So my question is that how do I assign the material parameters of fluid which exists in the void of porous materials to the domain? Thanks
↧

external pressure direction in Two-phase flow, moving mesh(tpfmm)

February 19, 2013, 8:09 am
$
0
0
Hello every one!

I have a question

I'm trying to build simulation using laminar two-phase flow, moving mesh(tpfmm)

and there is a external fluid interface with external pressure and surface tension.

When I put value in external pressure, I think the direction of pressure will be normal to surface,

but i want it to be just z direction

I have no idea to make the external pressure direction into z direction..

Is there anyone who knows it?

I appreciate any advice!
↧

Electrode modeling - diffusion

February 19, 2013, 9:39 am
$
0
0
Hi everybody, I am new to COMSOL and I need to model a 2D problem. I have two electrodes (a generator and a collector) immersed in a support electrolyte of 100mM of KCl in which there's a 1mM of Fe(CN6)^(4-) which will become Fe(CN6)^(3-). I need to analyze over time the concentration, taking into consideration the diffusion only (not the convection). Can you help me to set up the problem? I defined the geometry and the control volume, but now I'm stuck in the definition of the problem.
Andrea
↧

peristaltic pump

April 19, 2010, 5:47 am
$
0
0
Hello,

I have some question about peristaltic pump the model Comsol, "peristaltic_pump.mph (Model Library Path: COMSOL_Multiphysics / Multiphysics / peristaltic_pump) ".

(a) The Comsol use this equation "netflow=netflowt-(inflow+outflow)/(2*Ttot)", but the correct definition of the net flow would be this equation "netflow=netflowt -outflow + inflow " ? Why of this division (2*Ttot) ?

(b) What would the value of the flow pumped by the end of a cycle?

b.1) Would be the integral outflow over time?
or
b.2) Would be the integral netflow over time?

Thanks
↧
↧

general pde mode, spherical coordinates

March 10, 2011, 11:52 am
$
0
0
Hi, everybody
I want to solve a differential equation in spherical coordinates (just “R” component dependent)
By “General PDE mode” (comsol3.4).
But there is no default spherical coordinates in the comsol .
Now how can I resolve this problem?
The simulation geometry is as following:
A----------------------------------------B
Regards
parviz
↧

Variables & Functions in Comsol 4.1

March 22, 2011, 2:56 pm
$
0
0
Hi,

I am trying to do something very simple that worked perfectly in 3.5a, but that I cannot reproduce in 4.1. I have the feeling that I am totally missing something, but I do not know what.

I define a global variable, myVar, and want to use it in a global function, myFun. The function myFun does not recognize the variable myVar (when plotting the function). Why???
Next, I want to use this function (which is a function of time) to define a boundary load (Model 1>Solid Mechanics>Boundary load 1). But the function is not recognized (it stays orange). Why???

I have put the example as attachment.

Thanks for any help.

Alois Pfenniger
↧
Search

comsol software

October 6, 2012, 7:17 am
$
0
0
Hai sir,

i'm studying final yr electronics and instrumentation dept... i do my project based on 6 axis torque force sensor using comsol software.. so please give your opinion and suggestions....
↧

Axial flux permanent magnet generator

December 5, 2012, 8:59 am
$
0
0
Hi Dr. Ivar/All,

Iam trying to simulate the axial flux permanent magnet generator with two rotor and a coreless stator sandwiched between two rotor.

Permanent Magnets are attached on inner surface of the rotor in such a way that magnets on two rotor are in N-S orientation.

I used the following boundary condition for the different domain under rotating machinary physics(rmm)
- For PM i used the constitutive relation remnant flux density from the Amperes Law
- For two rotor i used the BH realtionship
- I used the multi turn coil domain to model the coil
-used the prescribed rotational velocity for the rotation fo the rotor
-used continuity

Apart this i used the free tetrahedral meshing .

I tried to simulate taking reference from the generator model in Comsol model library but still not getting the desired flux and the voltage.

I really need your suggestion regarding this matter.I tried to find out the discussion regarding the axial flux permanent magnet generator in the discussion forum but none of them are answered. I am stucked at this point please help me out .

I have attached the model by clearing all the mesh and solution for making it appropriate for uploading.

Thank you
Aruna

↧
↧

Pressure boundary conditions

February 14, 2013, 11:02 pm
$
0
0
Hi All,

I am working on a coupled problem involving a piezoelectric and fluid.....I need to apply the pressure from the piezoelectric after each iteration step and apply it as a pressure boundary condition on the fluid.

Can anyone give me some ways to solve this problem.

Regards.
Rahul Kishor
↧

About conductive electrodes of piezoceramics layers

February 17, 2013, 11:49 am
$
0
0
Hello everyone,

I am working on a piezoelectric energy harvester(substructure and a piezoceramic layer). I am applying a point force on the substructure and measuring the voltage from the surface of the piezoceramic to obtain voltage FRF (voltage/point force).

I want my model to account for the conductive electrodes bracketing the piezoceramic layer so that I can obtain uniform potential distribution throughout the surface of the piezoceramic. However, I couldnt find the appropriate boundary condition for this purpose.

I appreciate any help,
Bugra Bayik.
↧

Sloshing Tank with FSI

February 18, 2013, 1:44 am
$
0
0
Hello All

I calculate the waves of a water tank and then damp with a structure the waves. At the beginning I start with a single excitation an then wait and just let the gravity do the job. My model is similar to the sloshing tank example but rebuild with the FSI. I added then a bar which is made of rubber with a damping loss factor.

Now the problem: When the young modulus is 10e9 the model works fine, but the bar moves only for um. When I reduce the young modulus to 1e9, the model didn't converge. Does anybody know how I can make this model more robust? I would like to see the bar swinging within the waves and set the damping factor an the size of the bar to optimally damp the waves.

My model is attached.
↧
Viewing all 26527 articles
Browse latest View live
Search