circular variable dependency detected
Hi, The author of one paper has defined the conductivity as a function of current density and current density as a function of conductivity. In comsol, it gives a circular dependency error. How to get...
View ArticleGas detonation in the pipe
Dear colleagues! Please help me! I need to simulate process of C2H2 and O2 mixture detonation into the cylindrical tube. But I not sure, is it possible in COMSOL? Mixture ignition started from closed...
View ArticleImposing a rotating boundary
Hi, I am trying to build a laminar flow model with a rotating boundary to shear the flowing liquid. Unfortunately, when I impose the equation of this rotating boundary, the rotation equation appear...
View ArticleCoupling a ODE to the Boundary of a Laminar Flow Simulation
Hello, I'm trying to simulate blood flow in a tube using a mechanical circuit known as the Windkessel model. This model relates outlet pressure to velocity through a set of equations: (1) P = RT*V_avg...
View ArticleExtraction at Arbitrary Points and NaN
I have gone through the matlab-comsol livelink manual, and I understand that the NaN output value occurs when the extraction point is outside of the computation domain; but in this case the point is...
View Articleyield stress
Hi I'm trying to understand how can i define yield sterss for a bingham plastic material in COMSOL. The stress expression for this model is: shear stress = yield stress+m*(shear rate) Any comments on...
View ArticleCoaxial Borehole heat exchanger
Dear COMSOL users, I work on geothermal heating systems using borehole heat exchanger (see file attached for general functioning of coaxial geothermal exchanger). To that purpose, I use non-isothermal...
View Articleheat transfer in fluid flow
Hi, I have trouble in solving heat transfer in fluid flow with a 2 dimensional porous media, but the temperature i set in the boundaries cant take work. can you share me some case simailar to my work...
View Articlewelding simulation
hi, i am trying to process model tig welding of metal. i solved for temperature profile in my 3d comsol 4.2 model. Now how can i define the elements which are greater than melting temperature as...
View Articlefailure to find solution in newer version of COMSOL
Hi, I am a student with very minimal experience with COMSOL (most of what I know, I have learned just from experimenting with the program). I am modeling fluid flow through a flow chamber (see attached...
View ArticleHow to simulate the water boiling by Level-Set method
There is a good example simulating water boiling by phase field. I am trying to use the Level-Set method. However, I was frustrated by many times of failure. My problem is how to deal with the...
View Articlehow to plot error vs iteration number comsol?
All I can see is the "reciprocal of step size" vs "Time step" in the progress window of the solution but I do not know how to plot error vs iteration number in comsol. Can I do it real time or it will...
View Articleunknown property warning
Hi , I was wondering if anyone is familiar with this warning in the log window : " Warning: Problem encountered during results while solving. Unknown property. - Property: usetunit " It gives me the...
View Articleerror vs. time in iterative solver
Hi, I'm using "Transport of Dilute Solution in Porous Media" and the solver is "iterative". I expected to see "error vs. time" graph while solving the problem but still I see "reciprocal vs. time" as...
View ArticleEnzymatic reactions - Laminar flow + Transport of diluted species
Hi ! I would like to stimulate a simple reaction A=>P (in presence of E) by considering A as substrate, E as enzyme and P as product. This reaction will takes place inside a rectangular glass...
View Articlesolution as initial condition.!
Hello all, I have solved a model of flow over a sphere initially with stationary solver, and I have used this stationary solution, as initial condition for further time dependent study. I got the...
View ArticleModeling a falling stream of liquid in air: Time-dependent vs. Stationary
I am trying to model the shape of a stream of oil falling down from a tap to familiarize myself with laminar two-phase flow. By editing the oil drop example in the model library, I was able to solve...
View ArticleReynolds Number
Hi everyone, First off thanks for looking at my question and any feedback you could give me would be greatly appreciated! I'm trying to run some CFD modelling but I'm not sure the flow would be laminar...
View ArticleRunning 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 ArticleCOMSOL support for GPU-acceleration for CFD simulations?
Dear COMSOL-Team, are there plans to include GPU-acceleration into COMSOL CFD simulations (such as ANSYS FLUENT or openFOAM/RapidCFD)? I am working in microfluidics with multi-phase flows, i.e....
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