## Nonstandard Constraints and the Power of Weak Contributions

##### Temesgen Kindo October 16, 2018

For a flexible and physics-independent way to extend the applicability of the COMSOL Multiphysics® software, you can implement nonstandard constraints using the so-called weak contributions.

Ler Mais##### Temesgen Kindo September 21, 2018

Learn how to solve variational problems featuring multiple dimensions, higher-order derivatives, and multiple unknowns with a fun example: image denoising in a grainy photograph.

Ler Mais##### Temesgen Kindo September 17, 2018

Learn 2 methods for enforcing inequality constraints in your variational problems, the Lagrange Multiplier method and Augmented Lagrangian method, as well as the theory behind them.

Ler Mais##### Temesgen Kindo September 11, 2018

This post is helpful if you use equation-based modeling: Learn a variety of different methods for dealing with numerical issues when enforcing constraints in variational problems.

Ler Mais##### Temesgen Kindo September 7, 2018

In part 2 of a blog series on solving variational problems in COMSOL Multiphysics®, we discuss how to specify general boundary conditions and constraints.

Ler Mais##### Temesgen Kindo September 4, 2018

In this introduction to a 5-part series, learn how to solve variational problems using equation-based modeling, which is useful for modeling soap films, catenary cables, light beams, and more.

Ler Mais##### Temesgen Kindo June 28, 2017

The ability to create and use methods in COMSOL Multiphysics® is useful for automating your modeling processes, such as choosing physics and studies.

Ler Mais##### Temesgen Kindo May 17, 2017

Learn how to implement stop conditions for time-dependent and parametric solvers in COMSOL Multiphysics®, as well as scenarios for when and why you should.

Ler Mais##### Temesgen Kindo May 9, 2017

By exploiting maximum principles in large and complex models, you will save time and computational resources without having to buy a bigger computer or leave your model to solve overnight.

Ler Mais##### Temesgen Kindo October 6, 2016

In a previous blog post, we discussed integration methods in time and space, touching on how to compute antiderivatives using integration coupling operators. Today, we’ll expand on that idea and show you how to analyze spatial integrals over variable limits, whether they are prescribed explicitly or defined implicitly. The technique that we will describe can be helpful for analyzing results as well as for solving integral and integro-differential equations in the COMSOL Multiphysics® software.

Ler Mais##### Temesgen Kindo October 5, 2016

Cylindrical coordinates are useful for efficiently solving and postprocessing rotationally symmetric problems. The COMSOL Multiphysics® software has built-in support for cylindrical coordinates in the axisymmetry physics interfaces. When defining custom partial differential equations (PDEs) using the mathematical interfaces, paying close attention to their meaning is important. The PDE interfaces assume partial differentiation in a Cartesian system, requiring manual coordinate transformations to change to a cylindrical system. See how to account for such coordinate transformations when using your own PDEs.

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