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weak formulation

Can I get the weak formulation of two equations in attached file ?

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exporting data

Hi all I have a 3D cube and I need to get isothermal lines at the surface of the cube.If I am using the contour plot (line) option but the quality of isotherms are not good. Can anyone tell me how to...

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Defromed Mesh

Hi everyone. I designed a 2D rectangular object with a deformed mesh composed by a set of points interpolated between them in order to realize lines. How can I "move" such a structure in COMSOL 3.5a (I...

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Total Mass and Mass Flow Rate discrepencies

I have a pipe that flows air through a porous media. I calculated the mass flow rate by doing a surface integral across my inlet and outlet. I put fp.rho*v in the integral expression box (where v is...

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liquid thermal expansion by comsol?

Hi I want to simulation air thermal expansion in a sealed chamber, leading to a deformation of PDMS thin membranes on the top of chamber. I can not find suitable example form COMSOl. Does anybody give...

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Modeling a transient plane-wave

Hi, I have just started learning myself Comsol 4.1. I have earlier experience with version 3.5 , though. My question relates to time-dependent transient analysis in RF-module. I would like perform a 2D...

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Step function

Very simple question, but I can't find out how to do it. I have a external temperature, "Temperature 1", which is 100 C. After 330 seconds I would like it to drop 80 degrees to 20 degrees. I should be...

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PML refractive index

Hi, I am studying a model of Step index fiber and I want to put a cylindrical PML around the core. What should be the refractive index of the PML , should be same as refractive index of the cladding or...

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Modal Mass calculation

Hi Is it possible to calculate the modal mass for a particular mode shape? Can someone please explain how to do it.

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Error in comsol: Automatic scaled regions cannot treat selections without...

I am trying to simulate an optical nano-antenna where I used a spherical coordinate. However I am getting an error like "Automatic scaled regions cannot treat selections without exterior and interior...

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Metamaterial relative permittivity

Hi everybody. I realized with MATLAB (not LiveLink) a metamaterial permittivity distribution. It consist in (x,y) point coordinates and relative "epsilon" values, like: x y val 0 1 0 .... 4 2 10 .......

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question in the blood vessel tutorial

In the attached tutorial, on page 15, the force (boundary load) in the x,y,z directions is specified with a negative sign. I am wondering if someone can explain what the negative sign signifies. I am...

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Axial flux permanent magnet generator

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...

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changes in geometry

hi, am designing a 3d comb drive accelerometer, i have made some perforations in the proof mass( circle) when i run the model, shape of perforations changes to octagon..cud any1 help me wit this..

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magnetic-Fluid-Structure Interaction in a Network of Blood Vessels

The blood vessels are embedded in a biological tissue (the cardiac muscle) and, during the flow of blood, pressure is applied to the internal surfaces producing deformation of the vessel walls. In the...

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Time derivative of a surface integration in 4.3

Hi I'm using the magnetic field (mf) physic in time dependent study. I want to calculate the voltage V(t), as v(t) = - d/dt(flux phi) (time derivative of the magnetic flux). I serched the docs and...

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Later version of COMSOL has robuster and stabler solvers

Dear all, I just want to share my recent experience with a convergence problem. During last several weeks I was struggling with convergence problem. The model has two 2nd-order PDE and Electromagnetic...

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Cluster computing with HPCS 2008

How can I share the Comsol with the compute nodes. Please give each step to do this.

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Specified shear boundary condition

hello friends, i am trying to model a problem in which i have to use the boundary condition of wall as moving wall and the boundary condition of teh bubble as zero shear stress condition. How to...

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calculating a flux through a curved surface

Hi, I working on solving the electrokinetics problem in the attached geometry. I solve the problem but I am having problems with post-processing. I am interested in calculating the flux through the...

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