What's the meaning of this error?
Undefined value found. - Detail: Undefined value found in the stiffness matrix. There are 50197 equations giving NaN/Inf in the matrix rows for the variable mod1.theta at coordinates: (0,0),...
View ArticleUsing 'if' statement with two conditions
Hi, I want to use and if statement in COMSOL but I need it to have two conditions. I want to calculate the value of the x coordinate when y = 0 and T=300. Something like: if(y ==0 and T == 300, xi ==...
View ArticleBoundary electromagnetic heat source and convective cooling
Hi, I am modelling amicroelectrode array with joule heating module. The structure consists of a glass substrate block, an electrode array (spiral or parallel) on top of the substrate, and a fluid...
View ArticleHow to loop simulations in Comsol 4.2a with Matlab
Dear comsolers, here is an example on how to loop simulations. I'll let you decode it. 'Preprocessing' that I did before the loop: 1. Build a model in Comsol (attached). 2. Save As Model M-File...
View ArticleSplit complex variable in real and imaginary parts and iterative solver...
Hi, i'm tring to simulate an indutcor that produce some joule heating on a thin slab. This slab is a non linear material and has a HB curve. I work with 30kHz and i'm using a frequency solver with an...
View Article2D interpolation of material properties as function of Temperature and Pressure?
Hi, I see that COMSOL 4.2a allows 2D interpolations, how would that be used to interpolate fluid properties, such as density, conductivity, cp, etc, as functions of temperature and pressure of the...
View ArticleCreating randomly placed beads/particles in COMSOL?
Hi, I am trying to model a uFluidic capacitor system for electrical impedance spectrometry. It would be ideal if I could create a variable (> 1000) particles with certain properties (permittivity ,...
View Articleabout AC signal calculations in Comsol
Hi all, I am curious about AC signals in Comsol. Why do we need to add an analytic function from the functions subtitle to work with an AC signal? I added a waveform of square wave. If I do not place...
View ArticleMesh dependent results
Hi, All I solved a simple electrostatic problem for computing the potential field (V) in a tube (axisymmetric problem) filled with water. At one end I imposed a voltage of 500V and grounded the other...
View Articlelimitations of number of data in table or result.
Hi, I am using the transient solver in RF modual, and recording the time-varying electric field. For example, I have the following setteings: Comsol is set to record the electric field at a given point...
View ArticleElectric Field norm evaluations
Greetings, Is there a way to get the value of the electric field norm by putting in exact coordinates and getting an evaluation? I am trying to get the E-Field norm value right above the surface of my...
View Articleaxial flux pm generator error
Hi I am working on axial flux pm generator with two rotor and a stator( 3d model ) using the rotating machinery. I am getting this error while computing. I am using 16 magnets and domain 17 20 27 28...
View ArticleHow to find Current and electric field ??
Hello sir, I am student. and learning this Comsol 4.2 software..so i need a help.. My problem statement is like, one meter length semiconductor wire (Ge) and radius is 0.3mm. if i am applying 25V DC...
View ArticleNeumann BCs for Structural Problems
Dear Sirs, I would like to have some informations regarding the Flux/Source BCs in Comsol 4.2. I have read that they correspond to the Neumann BCs. I am using two different modules (General PDE and...
View ArticleThermal stress option seems to be missing
I'm looking to model stress and deformation in parts with differing thermal expansion coefficients as a result of a temperature change. Thermal stress is supposed to be available in the solid mechanics...
View ArticleTension Force
The material I am investigating has much lower tension limit than compression. So I want to use COMSOL to simulate the tension in the material, excluding the interference from compression. In the...
View ArticleConvergence problems in time dependent simulations
Hello, does anyone has experience how to solve convergence problem in time dependent simulations ? I tried to produce square wave input waveform from a sine wave input and using two diodes to cut the...
View Articleerror of tolerances
Hi, I am working on an AC model. The frequency of my signal is 1.3e10 Hz. I am specifying the time interval as (0, 0.1*T, 5*T) and I get an error: "Failed to find time step so that given tolerances are...
View Articleexport image file in java from COMSOL and also plotting while solving
I am running a bunch of 1 hour time dependent COMSOL models in a big 'for' loop. I can get Eclipse to export a .txt file for each iteration of the 'for' loop and I can show a progress bar and a 2D/3D...
View ArticlePML with structural mechanics
I am trying to use a PML with my model. The model uses solids and shells in the structural mechanics. The PML is around a solid block on five sides. However when I attempt to solve I get the error...
View Article