Support Knowledge Base

Solver Solutions

1262: Improving convergence of transient models

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...
Version: All versions - Platform: All Platforms

1261: Performing a Mesh Refinement Study

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...
Version: All versions - Platform:

1260: What to do when a linear stationary model is not solving

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...
Version: All versions - Platform:

1258: Understanding the Fully Coupled vs. Segregated approach and Direct...

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...
Version: All versions - Platform:

1257: Solving electromagnetic heating models with high-frequency loads

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...
Version: - Platform:

1255: Reducing the amount of solution data stored in a model

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...
Version: All versions - Platform:

1254: Controlling the Time Dependent solver timesteps

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...
Version: All versions - Platform:

1250: Running parametric sweeps, batch sweeps, and cluster sweeps from...

This solution describes how to launch a parametric sweep, a batch sweep, or a cluster sweep simulation in COMSOL Multiphysics® from the command line. Short Summary Model methods are presented as a concept to modify...
Version: All versions - Platform: All Platforms

1249: Solution number is out of range

You compute a distributed parametric sweep on a cluster. When processing the results some values are missing or you get errors such as "The solution number is invalid" or "Solution number is out of range". This issue...
Version: 5.3a - Platform: All Platforms

1245: Solving Models with Pulsed Loads in Time

I am solving a transient model which has loads that change instantaneously in time, but the solver appears to be missing some of these changes in the loads. How to I get the solver to correctly recognize when the load...
Version: All versions - Platform: