Effective index and singular matrix error
Hi everyone, I am trying to analyze a silicon waveguide by COMSOL 3.5 using RF Module - Perpendicular waves, and I need to find the effective index for a set of wavelength. I have had no problems to...
View Articlecapacitive transducer, Harmonic Perturbation problem, output pressure
Hello,everyone I'm trying to simulate a capacitive transducer to get the ultrasound with the vibratng membrane. In the begining I use 2D axial symmetry, MEMS module, Pressure Acoustic,Frequency Domain...
View ArticleCreep
good morning I designed creep model of steel bar. Heating the bar up to 1000 ° C and then apply a constant load for 600s. I only used the Marerial Model: Norton Why in the strain-time curve does not...
View ArticleFormula for Inductance coil?
Hi, I'm simulating a coil in comsol. And calculating the coil inductance with global evaluation. But what is the formula it's using? L=(N^2*u0*ur*A)/l doesn't give me the same results. Thanks!
View ArticleNo temperatures calculated by the "Conjugate Heat Transfer" node in the fluid...
I have a mechanic system consisting of fluid and solid parts. The problem is combined, it is mechanics and heat transfer. I need to calculate heat transfer through both components -solid and fluid. AND...
View Article1D transport LivelinkComsol Matlab funciton com.comsol.model.impl.StudyImpl
Hello, I try to couple COMSOL with other program using MATLAB [LinkLiveComsol], and I have the following problem that I cannot understand. Imagine you have a really simple advection-dispersion...
View ArticleHexagonal Crystal (Sapphire) Wafer Orientation
Hello, I am working with the solid mechanics module and I don't seem to understand the way Comsol treats a material with hexagonal crystal structure. I have a simple 3D rectangular solid structure that...
View Articlemoving mesh and electrostatics coupling
Hello everyone Have you ever encounter the moving mesh and electrostatics coupling problem? If you have,thank your for your advise Thanks a lot
View ArticleThe 'penalty method' in the 'Pull-in of an RF MEMS switch' model
In comsol 4.4 this model provides a very valuable method to calculate the pull-in time of an RF MEMS switch through transient analysis, but I'am a little confused about the parameter 'tn=5e5 pa'(...
View Articlefreeze-drying; convective heat transfer with Sublimation/Resublimation
Hi guys, I’m writing my bachelor thesis and want to do a simulation of freeze-drying of coffee with comsol 4.4, but I have not much experience with it. I made some tutorials and simulated examples...
View Articlesimpel model of an extruder
Hi, We are struggling with a simpel representation of an extruder. We first want to simulate a rotating rod in an concentric cilinder. The fluid around the rod is water (laminar flow). Later on, we...
View ArticleTemperatures missed in the solid area in "Conjugate Heat Transfer"...
Why are no Temperatures calculated in the 'solid' domain, while they are calculated in the fluid domain. I easily understand that no velocities can be calculated for the solid area, but temperature...
View Articlemagnetic field gradient in 3D return zero!
Hi everybody If anybody knows that why the gradient of magnetic field in 3D models is always zero? I checked the different methods. for example I wrote d(Bx,x) or different component of B and H. Even...
View Articleanalytic function in another analytic function
Hi, I have two questions: 1. an analytic cunction that has one argument - sigmaxx that I want to incorperate in another analytic function that has another argument = ec.normE. I cant do it no matter...
View ArticleImposing Dirichlet domain condition
Hello all, I wonder if there is a way to impose a Dirichlet condition not on a boundary but on a domain. Let's say, for instance, that at a time tn of my calculation I want to impose null velocity in...
View Articletime dependant simulation: variable input
Hi everybody, I am trying to simulate and validate an air solar collector model. I would introduce time-dependant (hourly time step) input for air temperature and solar radiation using an interpolation...
View ArticleHow can we use Poroelastic Wave Interface to simulate waves in partially...
Hello everyone, I have a question here: How can we use the Poroelastic Wave Interface to simulate wave propagation in partially saturated porous media in COMSOL Multiphysics ? Biot's theory is...
View ArticleAveraging
Hello, I run a diffusion test on a 3D model, I want to find average concentration over some cross sections along the x direction. is it possible? Thank you, Saeed
View Articlerigid solid 2D axisymmetric
I have created a 2D axisymmetric and I want to make one of the elements a rigid solid. However I cannot find the option in the right-click menu of the physics node. It usually is in domains in a 3D...
View ArticleLoudspeaker Modelling
Hi, I have a simple cabinet with a port on the front face. I then have half a sphere normal to the front face acting as the air domain. Firstly, how can I look at the modes inside the cabinet? Using...
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