Singular matrix, returned solution not converged
Hi, I have a Matlab code that solves four coupled differential equations, which works and gives me the attached plot. (The actual code is here: www.ee.ucl.ac.uk/~rjames/modelling/constant-order/oned/,...
View ArticleParametric Simulation with Automated Datasets and Plots?
Hello, undergraduate student and novice Comsol user here. I'm working on a parametric simulation and I'm finding the process of running the simulation, and then having to define all the datasets (for a...
View ArticleFailed to find consistent initial values. Last time step is not converged.
Hello I am a new user and I am running a natural convection cooling problem. I get below error "Failed to find consistent initial values. Last time step is not converged" How do i debug this error?...
View ArticleConvergence at high Velocity
Hello, I am trying to develop a model of nozzle flow into a cavity. I have a model that I am able to run at low velocities (0.1 m/s), but have not been able to get a higher velocity (~50 m/s) version...
View ArticleFluid flow and heat transfer in phase change material
hi I'm using Comsol 3.4 ,I am solving a conduction- convection heat transfer problem and fluid flow I got this error Error: Time 0: Repeated error test failures. May have reached a singularity. Last...
View ArticleHow to solve first-order PDE?
Hello, I try to solve 2D first order PDE in COMSOL, but unsuccessful yet. The equation is f_t + x*f_x + y*f_y = 0 with initial condition f(x,y,t=0) = y/x - log(x) on square area S = (1..9, 0..1). The...
View ArticleBeam excited by a shaker
Hi All, I aim to model a simple beam excited by a shaker. I am using the Solid Mechanics. I would like to know how big is the displacement of a particular mode (eg first flexural) when I excite the...
View ArticleCoupling 1D Pipeflow to 2D axisymmetric Porous Media
I am working on coupling 1D pipeflow to 2D axisymmetric porous media. The coupling is peformed by averaging the 2D boundary to the 1D point and integrating the 1D point to the 2D boundary. The coupling...
View Articlecan you explain what both of them(2D & 3D) is different??
Hi I'm trying to put the friction in BC. 2D is good working but 3D is not. So I wonder what the problem is and what differnt.... I attach these files of 2D and 3D. So if you have time to check them,...
View ArticleMesh, blocks and center
I have an array of blocks with these dimensions: length = 200 um; width = 6 um; height = 50 nm. I simulate the magnetic field inside these blocks (in certain conditions) and I need to get one...
View ArticleCalculating Mutual Resistance on Power Cable 2D -MEF
Hello everybody I'm trying calculating per-unit-length electrical parameters of a power cable buried in soil, cable consists of core and sheat, so i have 2 loops which are formed as follows: loop 1...
View ArticleMagnetic Field inside Gap of Toroid
Hi - I am new to COMSOL (going through tutorials now) and have some questions in regards to modeling magnetic fields. I want to model the magnetic field inside of an air gap in a circular toroid. I...
View Articlestudies with multiples steps
Hi all, there is something so weird with my COMSOL 4.3, when I create a time dependent study with different steps the solution only represents the last step and It is not posible to change the time...
View ArticleElectric currents resolve at every timestep
Hello all, I am trying to model a mesh that deforms (ALE) in proportion to the normal current density (ex. electroplating application). The issue I'm encountering is that I am not able to force the...
View Articlevariable geometry
Hi Ivar, It is me again. I would like to ask you something in relation with variable geometry, imagine two rectangles and suppose that one has a fixed geometry and you placed the other one on top of...
View ArticleMesh Problem: Inverted elements & Failed to create boundary layer, domain...
Hello everyone, I am trying to model a simple Shell and Tube heat exchanger. I have always the same meshing problem. Sometimes if meshing succeeds then during computing the message of avoiding inverted...
View ArticleDependent Boundary Condition
Dear All Do you know how to impose such a boundary condition in COMSOL for a simple flow in a channel? I want to impose u=du/dy at the lower wall of the channel (for example at y= -1m) (u is the...
View ArticleScattering of a plane wave by a nanosphere
I have been tried to simulate the scattering of a plane wave by a single metallic nanosphere using the RF Module, however with no success. During the computation process, an error message was shown....
View ArticleCoupling of Transport of Diluted Species with Darcy Flow with thin layers
Hello All, I'm working on a model of blood flow through a porous media. The blood flows through two main conduits an arteriole and a venule both of which have a main luminal region as well as a thin...
View ArticleHow to solve 6 Coupled Mode Non linear Partial Differential Equation
I am having 6 variables Ap_plus, Ap_minus, As_plus, As_minus, Q_plus, Q_minus Equations are in attached pdf variables have dependency of both time and space. I have tried pdepe Matlab but having...
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