get the error : Duplicate parameter/variable name. - Variable: mod1.ux

December 19, 2014, 1:06 am

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Hi all,
my computational model is composed of some sub-domains with different physics for flow. two have Darcy physics and third one uses laminar flow. in running simple steady state flow I faced this error. Can anybody help me?

Duplicate parameter/variable name.
- Variable: mod1.ux
Error in multiphysics compilation.
- Feature: Compile Equations: Stationary (sol1/st1)

Thanks,
Best

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meshing issues

December 19, 2014, 1:54 am

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hello,
I was trying to simulate a model which involves very fine meshing , can someone tell me what this error mean :-
Variables property does not include all degrees of freedom in xmesh.
thanks in advance ,
with regards
Jyotirmaya Ojha

Constraint found for variables in different Segregated groups

December 19, 2014, 2:26 am

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Dear All,

I got this error when I start to run a steady state system composed of 4 Darcy Law and 1 laminar flow!

Can any body help me?

Constraint found for variables in different Segregated groups. Try to merge these groups.
- Feature: Stationary Solver 1 (sol1/s1)

Thanks,

Multibody dynamics- Error while using Livelink with inventor

December 19, 2014, 5:42 am

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I have synchronised my model in inventor with comsol and ensured every parameter between both of them is perfectly matched, but the initial physics which comes like Linear Elastic Material and Initial values have selected all domains but is showing Not applicable in bracket. Also i am unable to select any boundary while trying to create an attachment or applying boundary load. Please help if you know about some trivial mistake which i am making.

How to display a specific ray trajectory?

December 19, 2014, 6:08 am

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Hello all,

In Ray Optics module, when I simulate a light ray injects onto a water drop, how can I display a specific trajectory, e.g., the trajectory that refracts first, then reflects and then refracts again?

Regards,
Tony

Cannot extract data from two datasets properly

December 19, 2014, 6:11 am

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I'm using COMSOl 4.4 LiveLink with Matlab (R2012b).

I've run a time-dependent simulation with two studies, where I've implemented a stop condition for the first time-dependent study, and then used the solution from the first study as the initial condition for the second study.

The problem I'm having is that the first solution contains 44 time points, while the second solution contains 197 time points. When I load the model into Matlab and try to use mphglobal, for instance, to extract data from the second data set, it only gives me the first 44 time points' worth of data. Am I missing something?

When I access the solution information of the model using mphsolutioninfo(model), it shows me that the two datasets have the proper size (see below):

>> info.sol3

ans =

dataset: {'dset3' 'dset4'}
study: 'std2'
sequencetype: 'SolverSequence'
values: {[1x197 double]}
parameters: {'t'}
mapheaders: {'t' 'Inner' 'Outer'}
map: [197x3 double]

>> info.sol1

ans =

dataset: 'dset1'
study: 'std1'
sequencetype: 'SolverSequence'
values: {[1x44 double]}
parameters: {'t'}
mapheaders: {'t' 'Inner' 'Outer'}
map: [44x3 double]

Any suggestions?

Thanks

Dave

Ubuntu 14.04LTS installation notes

December 19, 2014, 10:41 am

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I just installed COMSOL 5 on Ubuntu 14.04LTS. Here are my notes in case they could help somebody.

Linux install is a bit of a pain because COMSOL's idea of "support" for unix is, umm..., calibrated differently than for other OS's. In any case, linux install was well worth it. In my preliminary benchmark linux was _twice_ as fast as Windoze running COMSOL and seems to use memory more effectively.

Notes:

-- COMSOL on linux requires LSB support that is not in Ubuntu 14.04LTS by default. Before installing COMSOL you should run

sudo apt-get install lsb-core

to install the LSB dynamic linker

-- I dowloaded COMSOL50_glnxa64.tar.gz. I untarred. Changed to the untarred directory. I ran "sudo ./setup". Answered the questions. Took defaults. Specified my license file, my names, etc.... Click Install. Everything seemed to install OK with no error. The whole pile goes into /usr/local/comsol50 and noplace else. Obviously this approach doesn't give you a working installation. The COMSOL devs don't know about RPMs and such, apparantly.

--No license manager startup is installed. I had to do this manually. The COMSOL devs apparantly have never heard of upstart and such. There's a template rc script in

/usr/local/comsol50/multiphysics/license/glnxa64/rc.lm

You can edit this rc script and paste it into /etc/rc.local before the exit 0. Make sure /etc/rc.local is executable. Reboot and this should start LMCOMSOL

--No desktop icon is created by the installer, nor is there a "comsol" command in the command line path.
You'll find some windoze icon files in the installer directory. I converted one to PNG using gimp. Adding desktop launchers are descripbed here help.ubuntu.com/community/UnityLaunchersAndDesktopFiles

--If you'd rather have a comsol command to run from the command line you can make a symblink to /usr/local/bin as described in COMSOL support "solution" 1086. But be careful cutting and pasting. The command for creating a symbolic link is incorrect. It should be

sudo ln -s /usr/local/comsol50/multiphysics/bin/comsol /usr/local/bin/comsol

not what appears in the COMSOL solution

sudo ln –s /usr/local/comsol50/multiphysics/bin/comsol /usr/local/bin/comsol # WRONG!

That one had me going for a few minutes.

-------------------

Anyway, I hope this helps somebody.

PML for infinite layered films

March 21, 2013, 9:55 am

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Dear folks,

I am trying to simulate a point source illuminating on a stacked films extending to infinite. A intuitive way to truncate the film, I think, is to use PML. However, when extending the layered film material into PML, the performance of PML obviously is not good, even worse than Scattering BC without PML. I attached a figure showing the field, compared to a FDTD result, reflection from the PML boundary is apparent. COMSOL technique support also indicates that PML does not work well for infinite films, and suggests to live with SBC. So I am wondering is anyone here has encountered similar problem and can share the experience. Thanks a lot.

Best Regards,
Leiming

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Import projected view in Matlab

December 17, 2014, 5:59 am

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Hello,
Is there a function to import projected view in matlab?
I work on a quite complex geometry with some part were imported manually from other software.
This defines my base geometry. Now I need to add some points using matlab (will be my source and measure points in electrostatic.)
For that I would need to know the contour of some area. (in coordinate)
Is there a way to have comsol tell to matlab the vector constructing an object?
If any of you would know how to do that, you would save me!
Thanks,
Regards
P

coupling matrix of platinum and polysilicon ?

December 19, 2014, 8:51 pm

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we are designing cantilever. how to find coupling matrix of platinum and poly silicon??? Help me please....

define wall boundary between some boundary in one physics

December 20, 2014, 12:13 am

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Dear All,

I want to define wall boundary conditions between some domains of same physics when I am using Darcy physics. When I want to select that boundaries, they are non applicable. does anybody know How I can do that?
I dont want that walls to have same pressure. I mean the continuity of variables should not be met!

Thanks,
Best,

coupled nonlinear odes bvp

December 16, 2009, 4:03 am

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I want to solve coupled nonlinear ODEs. It is BVP. Anybody can help me in this regard.

Undefined value error with Scattering Boundary Condition

November 25, 2014, 3:38 am

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Dear all,

I try to set up an eigenfrequency simulation for an optical nanostructure, where its eigenmodes and corresponding Q-factors should be simulated. To do so, an air cylinder with scattering boundaries is placed around the structure. This method was already used in our research group with Comsol 3.5a, where it perfectly worked. If I try this in the same way as before in Comsol 4.4 I get an error that says that some undefined values where found (I put the complete error at the end).
Even if I take an working mph-file from 3.5a and load and rerun it in 4.4 I get this error.
To demonstrate it, I created a smaller simulation in Comsol 4.4 that should just calculate the optical eigenmodes of a silicon disk. It is attached to this message.
I know that I could also use a PML around the simulation volume (which I already did and which works), but in my particular case I would like to use a scattering boundary. You find the complete error at the end of this message.

Thank you.
Hannes

Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
There are 4992 equations giving NaN/Inf in the matrix rows for the variable comp1.E10.
at coordinates: (1.95739e-006,4.10639e-007,1.5e-006), (1.93312e-006,5.12863e-007,1.5e-006), (1.33784e-006,1.48666e-006,1.5e-006), (1.2579e-006,1.55489e-006,1.5e-006), (1.31557e-006,1.3701e-006,1.5e-006), ...
There are 1664 equations giving NaN/Inf in the matrix rows for the variable comp1.E20.
at coordinates: (1.23741e-006,1.44043e-006,1.5e-006), (1.27943e-006,1.26486e-006,1.5e-006), (1.52137e-006,1.29824e-006,1.40898e-006), (1.4484e-006,1.23084e-006,1.5e-006), (1.85009e-006,7.59702e-007,1.40843e-006), ...
There are 1664 equations giving NaN/Inf in the matrix rows for the variable comp1.E21.
at coordinates: (1.23741e-006,1.44043e-006,1.5e-006), (1.27943e-006,1.26486e-006,1.5e-006), (1.52137e-006,1.29824e-006,1.40898e-006), (1.4484e-006,1.23084e-006,1.5e-006), (1.85009e-006,7.59702e-007,1.40843e-006), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns.
- Feature: Eigenvalue Solver 1 (sol1/e1)

heat transfer in a tissue from a network of tubes

December 21, 2014, 12:41 am

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i need to know the formula to calculate the amount of heat transferred in a minute from a tissue, with a certain volume and kept at constant temperature, to the fluid, contained in a network of pipes, flowing with a certain flow/minute and at a certain inflow temperature, supposing that temperature of the tissue and the temperature of the pipe fluid equilibrate (get the same) at the outflow of the fluid from the tissue

when you toss in gambling

December 21, 2014, 8:30 am

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and blow the doors off the Bucs

December 21, 2014, 9:27 am

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[url=givemn.org/teams/carolina-pant...e-stream5497109ebab2f]Carolina Panthers vs Cleveland Browns live stream[/url]
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Importing .mphtxt/.mphbin file into COMSOL4.1

March 16, 2011, 10:39 am

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Hi,

I created a geometry in Eclispe(COMSOL API) and saved that in ".mphtxt" format. When I try to import through server it shows the following error:

The bundle class path entry "e4-workbench.jar" could not be found for the bundle "update@plugins/org.eclipse.ui.workbench_3.6.0.I20100603-1100.jar"

and many more errors of this kind.

Am I missing some files in my Comsol Multiphysics package?

Thanks
Sandeep

Undefined value found in the stiffness matrix.

November 10, 2012, 12:28 pm

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Hi I am Getting Following error when I am trying to solve Mosfet model in comsol

Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
.There are 9 equations giving NaN/Inf in the matrix rows for the variable mod1.phi0
. at coordinates: (1.85106e-007,-3.45295e-007), (7.68991e-008,-2.18897e-007), (1.31003e-007,-2.82096e-007), (8.2885e-009,-3.71345e-007), (9.66972e-008,-3.5832e-007), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns.

thanks and regards

Pavan Naik

Time dependent alternating temperature/thermal insulation boundary conditions

June 14, 2013, 8:15 pm

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Hi all,

I am trying to setup alternating boundary conditions for a certain boundary based on the hours of each day. My model will run for about 2 months, and I would like to set the boundary condition such that:

- 0-6 hours: Temperature BC
- 6-24 hours: Thermal insulation BC

The boundary condition would switch from Temperature to Insulation and vice versa each day until the end of running. I am wondering if this is possible, or if there is a more practical approach.

I would be grateful if you could help me. Thanks,

--
Tolga

MATLAB parfor and Comsol server

June 29, 2014, 3:37 am

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Hi,
I want to speed up my computations using the parfor loop in MATLAB (from Parallel Computing Toolbox). I run this on a Linux machine. My code so far:

system('killall -9 comsollauncher java'); % kill previous running Comsol server instances to prevent port assignment problems
pool = parpool('local',2); % open local pool with two Workers
parfor i=1:5 % set this to 2 iterations (=number of workers in pool) and it will work
comsolPort = 2036+i; % set unique port
system( ['comsol -np 1 server -port ',num2str(comsolPort), ' &'] ); % start a Comsol server
pause( 6 ) % give Comsol server time to start up
testfun(comsolPort) % function connects to the given Comsol server using mphstart(comsolPort), does some Comsol stuff and later disconnects
end
delete(pool); %close pool

Using 2 workers the code works if parfor makes only 2 iterations. But if there are more iterations mphstart() cannot connect to the given Comsol server throwing:

"Error using mphstart (line 152) A connection to Comsol could not be established. Please check that a Comsol Server is started prior to calling mphstart"

although a new server is definitely running on the given port. This might be related to how the MATLAB job scheduler works. But I have no idea why and how to fix this. Having only as many parfor iterations as workers in the pool is not optimal, because I have to run far more cases than there are CPUs/workers on my machine. Do you have any suggestions how to make this work?

Thank you and best regards,
Chris