Problem with Neumann boundary condition definition
Hi, I am simulating a Helmholtz equation (using the PDE mode module) with a Neumann boundary condition. Some days ago, we decided to update our Comsol version from 3.4 to 4.0. In the new version we...
View ArticleWhat's the difference between Form a union and Form an assembly?
comsol version 4 In Geometry, there is an interface called Finalize (Form Union or Form Assembly). What's the meanings of Form a union and Form an assembly? Is it like this? For example, when I creat...
View ArticleHow to get the current from current density
Hi Everyone, I am simulating a piezo electric transducer in COMSOL Multiphysics 4.0a. In order to get the impedance of the transducer at different frequencies, I need the current flowing at the...
View Articlepulse train
Dear sir i try to get generated heat in cable termination as a result of pulse train ( apply for 5 hours) first i want to generate the pulse train (0.5ms ON and period 1 ms) the value of pulse equal to...
View ArticleQuestions about Darcy's model in Comsol gallery
I have some questions regarding Darcy-Brinkman example, Which I have found online in Comsol gallery. I will be more than happy if you can help me to figure out my problems or tell me how can I find my...
View ArticleModelling transport of species in porous media
Hi everyone, I hope someone can give me some advice. We are currently modelling pyrolysis of large coal particles which involves including for reaction kinetics, heat transfer and mass transfer. We...
View Articlecombined time-dependent and stationary solvers
Hi I have a coupled system of solid mechanics and magnetic field, and I want to solve the magnetic equation in time domain and solid mechanic ones in stationary case. they are bidirectionally coupled....
View Articlewhy the scattering cross section calculation result is negative?
Hi, I am doing some calculation with comsol 4.2a, and I manage to do the scattering cross section calculation for the sphere model. Then I use exactly the same model, but change the sphere scatter to...
View ArticleExtract data of a contour at any time step
Hi everybody, In my results I have a contour and its position (i.e. x, y) is changed at any time step. I want to extract data of the location of that contour at any time step . Would you please help me...
View ArticleCurrent at the boundary
Dear User, What will be correct expression for current density in Joule heating module? I have 2D antisymmetric model. I want calculate current at the boundary. So, I need to integrate current density....
View ArticleDensity-limited diffusion
Hi, I'm trying to solve a set of 3 PDEs where one of the diffusion in one of the PDEs is limited by the value of one of the other variables, something like this: ut=... vt=vx*(D*(1-u))+... when I run...
View ArticleWill the increase of the relative tolerance reduce the solving time ?
Dear all, as mentioned in the title, I would know if the change (specifically an increase) of the relative tolerance in Time Dependent solver (but also in Stationary solver, why not) will reduce the...
View ArticleHow to specify the phase shift in electric currents (ec)
Hi, I try to reproduce the 3-phase cable simulation as shown in www.youtube.com/watch?v=ZCLcbSQB1-Q I used the electric currents physics and time-dependent. How to specify the phase shift among the...
View ArticleFinal Abstract Submission Deadline for COMSOL Conference 2013 Rotterdam –...
Dear COMSOL Users, The Final Abstract Submission deadline for the COMSOL Conference 2013 Rotterdam is Friday, August 23rd! Show the modeling and simulation community what you are working on, and get...
View ArticleCan cut line result be used in simulation?
I am currently using comsol to simulate a concentration lets name it C on a 2D symmetry rectangle. at one point I need to take a boundary value of C, I am wondering if there is anyway I can take the...
View ArticleSaving a file for later assemby
Hi, I want to model geometry of a complicated tool for later studies on Multibody dynamics module. As an start, I have created each part in different files and I have saved them as the mph file....
View ArticleSpecifying a rotating boundary condition
I would like to simulate a rotating wall condition. For simplicity, imagine a square box. On the top surface of that box there is a circle. Inside of the box is a viscous fluid. I would like to impose...
View ArticleStore part of solution for next run
Hi: I have 2D and 3D models of the same experiment which are in the same file. I would like to do two things: 1) Store the solution of the 3D run and store seperately the data from a "cutplane". 2) Use...
View ArticleDisplacement between two points
Hi I am very new to COMSOL and I am having trouble with calculating the displacement between two points. I'm using the structural mechanics module and I'm applying a body load to a an object and I want...
View ArticleApplying weak constraints in Darcy's law
Hi, I'm working on vapor intrusion modeling from subsurface into the overlying building. I have a large domain (100m X 100m) and a building (10m X 10m) with 2m basement is locating at center of the...
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