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Implicit solver in COMSOL

Posted Jun 14, 2018, 3:24 a.m. EDT Parameters, Variables, & Functions, Structural Mechanics Version 5.3a 1 Reply

Sai Elakkiya Venkatachalam
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Hi all, I am new to COMSOL.My research needs to couple the behavior of Mechanical Magneto thermal effect.I have non linear constitutive relation for magnetostrictive material which is the funtion of (sigma,H),I have to use implicit solver for solving this equation.Does anyone help me to solve the implicit equation in COMSOL? Another doubt is how to write our own implicit or explicit function in COMSOL?

1 Reply Last Post Jun 15, 2018, 10:20 p.m. EDT
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist
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Posted: 6 years ago Jun 15, 2018, 10:20 p.m. EDT

All equations are solved implicitly in COMSOL. If you choose "fully coupled", and damping factor of 1.0, this will be as implicit as you can get. However, it will likely not solve. In order not to solve implicitly, you can choose an explicit solver, but most solutions are not solved that way. This is because COMSOL automatically derives and includes the Jacobian matrix for you. You can also modify what is in the Jacobian by using the "nojac" operator. Indeed, look at the equation view to find where some of the equations already include the "nojac" operator due to some stability issues.

-Good luck to you !

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James D. Freels, Ph.D., P.E.
All equations are solved implicitly in COMSOL. If you choose "fully coupled", and damping factor of 1.0, this will be as implicit as you can get. However, it will likely not solve. In order not to solve implicitly, you can choose an explicit solver, but most solutions are not solved that way. This is because COMSOL automatically derives and includes the Jacobian matrix for you. You can also modify what is in the Jacobian by using the "nojac" operator. Indeed, look at the equation view to find where some of the equations already include the "nojac" operator due to some stability issues. -Good luck to you !

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