Running Comsol Desktop Model with Matlab Script: Updating Parameters
I am using a matlab script to update fluid parameters (viscosity and density) initially defined in comsol desktop. Based on some coupled physics, the density and viscosity of the fluid will change,...
View ArticleHow to set the variable with Fourier Transform when solving PDEs using...
Hello everyone My question can be simplified below: AIM: get a dependent field u(x,t) PDE general form: u_t=A(u,u_x)+B(u) Want to solve it using coefficient form. Problem: A(u,u_x) can be expressed...
View ArticleAutomating Comsol with Matlab: While Loop and Time Dependent Solver
I am running a comsol model with matlab; and I have a while loop in which the pressure values extracted from comsol at a time tmax corresponding to the iteration parameter, k of the while loop, is used...
View ArticleOverall sound pressure level (or pressure)
Dear, I have a problem to calculate "overall" pressure in ray acoustics module. I know equation for real overall (with diferent frequencys or bands), but in ray acoustics module we have direct and...
View ArticleFailed to find consistent initial values -- transport of diluted species
Hello, I am having an issue with the model I am running using Transport of Diluted Species in COMSOL version 4.4. I have a large circle enclosing many smaller circles. The smaller circles have a flux...
View ArticleConverting 2D model 3D.
Hi there, Can you suggest a way to import a 2-D surface in 3-D file and give it some thickness to make it 3D? I 've tried directly importing the file but it's filling all the voids in the 2D surface....
View ArticleThermal Wall functions
Can somebody elaborate on this from the reference manual pg (794) : "Wall boundary conditions for turbulent fluid flow. For the k-ε turbulence model, this condition is of the type k − r( ε ), −n · ∇ε,...
View ArticleMixture of sweep mesh+Tetrahedral mesh in a 3D model
I have a helical coil embedded in solid cylinder and was trying to figure out best way to mesh it since helix always creates problems. 1)I did a mapped mesh on one end of coil cross section. 2)Swept it...
View ArticleSave only probe measurement in parametric study
Hi everyone, I am quite new to Comsol, so maybe my question is easy to answer... I am doing a study with 3 parametric sweeps at the same time, with only one point of interest measured by a probe. My...
View ArticleConvergence on a Rotating Machinery Mixture Module (multi-phase flow)
Hello everyone, Quick question, I'm trying to simulate fluid flow (water and air) in a reactor. It is essentially a mixer with an impeller to induce the flow of water while air is introduced via two...
View ArticleParameter sweep breaking geometry
Hi all, I've been having a really frustrating problem with parameter sweep, and was wondering if anyone has any insight: I am simulating the 2D cross-section of a co-planar waveguide, and am sweeping...
View ArticleHow to get the time stepping information?
In my problem, I want to use event interface to model a stochatic event(an open-close markov process), its Monte Carlo trace need the information of time step, i.e. deltaT = t_next - t_current....
View ArticleSeveral BH curves for one part
Dear all, currently I'm working on a simulation approach for polymer-bonded permanent magnets. Therefore I need to implement several BH curves for one part. Based on the temperatur of every finite...
View ArticleOut of memory during LU factorization
Hi there, I am a new member in the COMSOL community. I am trying to solve a simple 3D problem having diffusion and chemical reaction within the subdomain. However, I am getting this message "out of...
View ArticleA error reads 'Failed to find a solution. Segregated Step 1 Singular matrix.'
Dear all, I built a cardiac cell model in 3D. There are two domains as the extracellular and intracellular space. Two Laplace's equations are applied to these two domains (∇∙8∇V_i=0,∇∙8∇V_e=0). Then I...
View ArticleSimple optimization in comsol 5.0
Hey Everyone I'm trying to do A simple optimization in Comsol 5.0 However it keeps giving me an error. In the attached image you can se how I set it up. A quick summary: under definitions I have...
View ArticleScale of dependent variables
When I run my simulation and look into the log under the time dependent solver, I found the following: Time-dependent solver (BDF) Number of degrees of freedom solved for: 7927 (plus 1444 internal...
View ArticleEquation-Based Modeling is dimensional or dimensionless?
Please help me to understand more clearly about dimension in the Mathematics branch (in Comsol 4.2). I would like to quote here some information from the User guide:"The Mathematics interfaces are...
View Articletwo phase laminar flow in 3d
hi I m supposed to simulate two-phase laminar flow problem (moving mesh). the size of a cyl is , r=5 h=5 The bottom of the cylinder is fixed and the top of the cylinder is moving with a certain speed...
View ArticleFind temporal location of the maximum of a variable
Hi, I would like to know at which exact time occurs a maximum of a variable, and so far I only got to know the maximum of this variable but not WHEN it occurs. I tried with the operator maxop1 but...
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