What is the difference between relative error and residual?
Hi, I've often experience the error message like, Failed to find a solution. The relative "error or residual" is greater than the relative tolerance. Returned solution is not converged. In this case, I...
View ArticleSolving nonlinear problem using parameter sweep
Hi, everyone! I am struggling to solve some nonlinear optical problem (the material has 3rd-order nonlinear optical response to the electrical-magnetic field) using Comsol RF-frequency domain module....
View ArticleChanging/resetting dependent variables while solving differential equations
Hello, I have a system of two differential equations in the form, x' = a*x^2 + b*x + c*y and y'=c*x + d*y a, b, c and d are parameters. Depending variables has to change to different values depending...
View Articlesimulating an imported mesh (from matlab)
Hi, I'm trying to simulate a prescribed displacement (one end is fixed and the other one displaced) of a mesh created in matlab (the geometry is from a microCT image). The problem is comsol dons't...
View ArticleHow to add z component displacement in 2D x,y plane for Solid Mechanics Module
Hi, I want to build a simple 2D (in x, y plane) model for SH waves in Solid Mechanics frequency domain. But I am having trouble in adding my prescribed Displacement in z direction (can be added only in...
View ArticleMeasure for deformation
Hi, I am looking at the deformation of microwells in an elastic structure. The model is working, but I am having some difficulties extracting useful data from the results. I would like to know how much...
View ArticleInertial Forces Representation in a Microfluidics Module
Hello, I am working on a simulation of a microfluidic system that involves both the effect of dean flow and inertial (lift) forces on particles travelling inside a microchannel. To my knowledge, COMSOL...
View ArticleIntegration and/or Maximum over frequencies for Optimization
Hello, I solve some problem in Frequency Domain with Optimization. In order to perform geometrical parameters Optimization I need an objective function that have to be derived for single defined...
View ArticleModeling Boltzmann Transport equation in COMSOL using coefficient form of PDE
Hi, I am modeling Phonon transport using Boltzmann transport equation. Referring: a. www.comsol.com/paper/nanoscale...tzmann-transport-equation-6408 b....
View ArticleHow to define a variable with simulated result
Hi, everyone, I am trying to run COMSOL file in COMSOL 4.4. My file originally works in COMSOL 3.5, but when i run it in COMSOL 4.4, one variable appears to be orange and I cannot get any result. I am...
View Article3D Lithium Air Model
Hello everyone, I am trying to build a 3D Model of a Lithium-Air-battery based on the 1D Version from COMSOL's model library. Everytime I run the simulation i receive the following error after several...
View ArticleProblem with Automatic Remeshing / MUMPS allocation factor increased to 1.44.
Hi there, I have built a COMSOL 2D model that uses deformed geometry, where the geometry movement is non uniform. I need to use Automatic Remeshing to update the mesh elements. But after some time (t =...
View ArticleIterative solver for Forchheimer flow
Dear all, I am relatively new to COMSOL so please bear with me. I have made a simple axysmmetric model with an inlet on the left hand side and an outlet on the right. The flow between the two has to be...
View ArticleSolve 2D Euler equations by using general PDE (g)
Hi everyone, I want to solve a 2D Euler equations using Comsol to save programming and debugging time. Here the Euler equation is used to describe gas expansion, thus it includes conservation of mass,...
View ArticleUnable to change the frequency of the model due to some error
Hi guys, I need some help regarding some kind of error message received, I had been doing the modelling regarding the heat radiation of a cell phone and wireless router to the human head/body. I am...
View ArticleNaN or Inf found when solving linear system using SOR in Double nano-Granting
Hi everyone, I am trying to simulate the intensity that a light beam through a double diffraction grating.However, when I run the computation, an error of "UNDEFINED VALUE FOUND" occurs, with detail...
View Articleray acoustics module
In the ray acoustics module, how to set up the background velocity of turbulence and how to extract the background velocity?
View Articleconvergence error during simulation
Hello, I am doing a hyperelastic simulation on a silicone rubber sheet with dimensions 50*50*5mm, with pressure being applied on the surface. But after a certain pressure range, I get this error...
View ArticleMultiphyscis two-step analysis
I have four models - Electric EC, Magnetic-MF, Heat Transfer-HT, Laminar-SPF. In Study-1 I solve for only the first three and exclude Laminar flow solution. In Study-2: I solve the Heat and Laminar...
View ArticleElectrostatically actuated diaphragm
Hello, I am part of a project to design an electrostatic speaker. I am using the electromechanics module to model in 2D the displacement of a charged diaphragm in an electric field. The diaphragm is...
View Article