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Where are weak contributions added in the governing equations?

When adding weak contributions to a particular physics, where are the weak contributions added in terms of the governing equations? Is it always on the left or right hand sides, or is it added...

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Try converting to triangular mesh on these faces

Dear sir, While meshing my model, only one domain didn't get meshed. And the error shown for a face which is not meshed is "Try converting to triangular mesh on these faces". And, I was not able to...

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Undefined Value Found

I was runing a 2D model and came up with this error.. anyone can help me?? Undefined value found. - Detail: Undefined value found in the equation residual vector. .There are 912 degrees of freedom...

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Problem with periodic boundary condtion.

I am trying to implement the advection equation with periodic boundary conditions using DG. I have specified homogenous Neumann flux on all the boundaries and then I have used the periodic condition on...

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Random nucleation

Dear all, I am currently involved in a phase change simulation. I have not yet found the way to deal with random nucleation occurring for instance during the quenching : during the transient heat...

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Problem in direction of magnetic field

Dear all , I simulated the Two coil system with ferrite core , with primary coil and secondary coil and both are separated by distance , i have problem that , if i am exciting primary with voltage...

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Can't save file after deleting one model

I started with one model, then created a second and afterwards deleted the first one completely. Now I am unable to save the file and I also can't run any study. I think there are some variables left...

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Heaviside function simulate Acoustic emission signal

Hello, I need to apply a Heaviside function difference to simulate a Acoustic emission burst signal. Can help, how can I do this? What model should I use? I'm new working with COMSOL. Thanks, Nuno...

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building a multicomponent gas mixture in comsol

Hello All, I was wondering if someone could help me with building a multi-component gas mixture in COMSOL 4.2. I have my biogas composition of 66% CH4, 33% CO2 and 2% H2S and I need to define...

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wave guide

Hi, I am starting study using Femlab simulation. I have problem. Actually, i want to simulate my metamaterial design but before simulate my design, i try simulate simple design. I just make rectangular...

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Problem Modeling Capacitive Cantilever Sensor

Hi, I want to find out the pull-in voltage of a capacitive cantilever sensor. To do so I did the following: I chose to do the 2D model first to get an idea, then I added Moving Mesh (ale), solid...

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How to set a radial polarized illumination ?

Hello, I am simulating a model and the source of the model is radial polarized illumination. However I do not how to set this incident light. I hope anyone who knows the answer can tell me. I use the...

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Parallel computing MatLab Comsol

Hi, I am using Comsol 4.3 with Livelink for Matlab. I run an optimization code in Matlab where i call Comsol to perform frequency response simulations. Now i would like to start two parallel frequency...

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Modeling a Sliding Constraint

I am trying to model a sliding constraint, basically a pin in a hole. To try to understand how best to apply the contraints I created a simple model of a tube and rod. The tube and rode are both 1 m...

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Modeling a Sliding Constraint

I am trying to model a sliding constraint, basically a pin in a hole. To try to understand how best to apply the contraints I created a simple model of a tube and rod. The tube and rode are both 1 m...

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Stiffness in bending mode

Hello Everyone, I have been COMSOL for quite sometime and have come across a problem that I can not solve very recently. My objective is to find out the bending stiffness of a metallic nanoplate. What...

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parasitic capacitance

hi, i m designing a capacitive comb drive accelerometer in this i want to take parasitic capacitance in to account in order to find capacitance but i cant find where it is...could you please help me out

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difference between "optimization study node" and "optimization module" for an...

Hi! Seems an optimization problem can be performed by either "optimization study node" or "optimization module". If use "optimization study node", the available optimization solvers include SNOPT and...

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mesh error

Hey, I was trying to follow the PDF on comsol website ( Model ID 15) to build a model for Helmholtz coil. I followed almost all the steps except for the dimensions, so the geometry should have no...

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Gain Medium with Circularly polarized light in COMSOL

Dear All COMSOL follows exp(-iwt) modeling in the and hence the absorption of the material is given by imag(permittivity) >0. If I want to simulate a gain medium, is it trivial to replace the...

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