Solver

Solving complicated models

Solution Number: 1267 Versions: All versions

I have a large, complicated, model that is not solving, or taking a long time to solve. What should I do? There are a number of reasons why a model may not be solving, or solving very slowly. This article describes ...


Memory leak in the Fortran Runtime Libraries

Solution Number: 1264 Versions: 5.4

When running running a model that uses the MUMPS solver repeatedly on my multicore processor, I notice a small gradual increase in Memory Consumption. Please make sure that your COMSOL Multiphysics 5.4 installation is ...


The MUMPS solver crashes or hangs during Cluster Simulation

Solution Number: 1263 Versions: 5.4

When running large models on a cluster with COMSOL Multiphysics 5.4, the MUMPS solver hangs or crashes. This issue has been fixed in Update 4 for COMSOL Multiphysics 5.4. Please update your COMSOL installation to ...


Improving convergence of transient models

Solution Number: 1262 Versions: All versions

Transient models involve computing a solution that varies over time. To do so, the software begins with the given initial conditions and computes the evolution of the unknowns using one of several different time ...


Performing a Mesh Refinement Study

Solution Number: 1261 Versions: All versions

How do I gain confidence in the accuracy of the solution to my problem? How do I perform a mesh refinement study? All of the numerical methods used within COMSOL Multiphysics® discretize the modeling space via a Mesh ...


What to do when a linear stationary model is not solving

Solution Number: 1260 Versions: All versions

I am solving a linear stationary finite element model but the software is not solving. Why? What can I do about this? A linear finite element model is one in which all of the material properties, loads, boundary ...


Understanding the Fully Coupled vs. Segregated approach and Direct vs. Iterative linear solvers

Solution Number: 1258 Versions: All versions

How, and why, switch between a fully coupled and a segregated approach to solving a multiphysics model? How, and why, switch between the direct and iterative linear system solver? ## Fully Coupled versus Segregated ...


Solving electromagnetic heating models with high-frequency loads

Solution Number: 1257 Versions: All versions

I am solving a Multiphysics problem involving electromagnetics and heat transfer. The electromagnetic fields are varying at a constant frequency, and the period is very short compared to the timespan over which the ...


Reducing the amount of solution data stored in a model

Solution Number: 1255 Versions: All versions

My models contain a lot of solution data, and I do not want my file sizes to get too large, it takes a lot of disk space. What can I do to reduce file size? Will this reduce the time it takes to solve the model? File ...


Controlling the Time Dependent solver timesteps

Solution Number: 1254 Versions: All versions

I am solving a transient model and changed the stepsize in the Times: field in the Study Settings, but the solver is still taking exactly the same timesteps. It seems the timesteps that the solver is taking are not ...


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