Nonlinear solver scheme
Dear Ivar, We are solving a nonlinear transient problem using a "fully coupled approach" with the constant Newton option (damping factor =1). The termination criterion is the default tolerance with a...
View ArticleUse a solution of a very similar problem as initial values...
Dear all, I am generating a phononic band diagram of a photonic crystal (mechanics-analogy to photonic bands...) by sweeping the bloch-floquet k vector from Matlab (i.e. a boundary condition - but in...
View ArticleBest way to find the average velocity over a cross section of an axisymmetric...
I'm attempting to find the average velocity over a cross section (of an 2d axisymmetric flow profile) vs distance along the flow channel (say z direction) in COMSOL. The only way I can find to do this...
View ArticleUMFPACK
I am using COMSOL 4, I want to solve a nonlinear equation. I can not find UMFPACK in solver list!!! Could you tell me where it is?! Thanks.
View ArticleHollow fiber membrane
I want to model hollow fiber membrane, I have a problem with reaction term in tube side. this term changes the continuity equation into nonlinear type. this model has three section; tube, membrane and...
View ArticleCalculation of effective material loss (alpha-eff)
I was wondering while doing my undergraduate research that- if there is any way to calculate the effective material absorption loss (alpha-eff) using comsol. I know the equation, but i do not know how...
View ArticleLimit number of eigenfrequency solved for
Hi, In my optimization process, I would like to maximize one cavity mode's quality factor. But since there is a neighbor mode has higher quality factor. Comsol always optimizes the neighbor mode...
View Articlehow to solve these equations using comsol?
Hello Mr. Ivar, I am a new comsol user and have read many froum posts of you, so learned and kind of you. Recently I have meet a equation set and don't know how to solve it. The equation are as follow:...
View Articlehow to solve piecewise equations with integration using comsol?
Hello everyone, I am a new comsol user, recently I have meet a problem and don't know how to solve it. The equation are as follow: X=0, when V<0.5; d(X,t)=V,when V>=0.5; V=sin(2*pi*t); I don't...
View ArticleSegregated Group Solver different results
Hi folks, I have been using COMSOL for a while now and, sometimes, when facing a difficult convergence problem I do mess around with the solvers a bit. I have seen some posts here on the forum...
View ArticleUsing lower limit node
Hi, I'm trying to use the lower limit node, but I can't select any variables because the variables window is not there. I can select variables in the segregated step nodes. See attached file for...
View ArticleHeat transfer modelling of selective laser melting
Hello everyone, How can I simulate melting of a powder media? To be more clear, when the temperature of a part in a powder bed exceeds melting point, it turns into molten material. After that when the...
View ArticleUnidirectional coupling of a time dependent study to a stationary study
Hello, I am using structural mechanics module and a stationary study to calculate stresses and strains in a simple 2D axi-symmetrical model. The model has a thermal expansion node. I have another study...
View ArticleOptimisation of processing parameters in laser sintering of metal/alloy powders
Hi everyone, I am new to COMSOL Multiphysics.. Can anyone help me in simulating selective laser melting(SLM)/direct metal laser sintering(DMLS) of metal/alloy powder media in layer-by-layer fashion? IN...
View ArticleInconsistent uni-directional constraint with Conjugate Heat transfer
I am trying to model a simple high temperature hydrogen heat exchanger with the conjugate heat transfer module. While I have been sucessfull in modeling individual tubes of the hydrogen alone, I cannot...
View ArticleFSI - High convergence problem
Hi all, I'm new to COMSOL and I have a problem that involves an interaction between air and a solid body. I am interested in the torque generated on the body by the moving fluid. My intent is to use...
View ArticleConvergence problems
Hi there, Could any one give a hand? I have no idea what is happening with the solver or the model. I am trying to model a laminar flow without any other physics. The default plots during solving...
View ArticleStudy
I would like to deform a component and strain it in the deformed state with internal pressure. How do I set up the study, so that these two processes run sequentially. The pressure load is to take...
View Articlethe mass matrix is zero
Hello I am trying to simulate my design. In the first step, I tried Mode Analysis but unfortunately I faced this error: The mass matrix is zero Please let me know how can I fix it? Of course I read...
View ArticleLaplace-Beltrami Operator on a Curved Surface
Hi all, When I use the Coefficient Form Boundary PDE (cb) on a curved surface, is differential nabla operator the generalized operator which implies the curvature, say, is the Laplace operator the...
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