## Equation-Based Modeling in COMSOL Videos

##### Phil Kinnane March 7, 2011

COMSOL Multiphysics offers direct access to mathematical models utilized in its interfaces and allows users to customize their own theoretical model within COMSOL with unparalleled ease. Here are three video tutorials on how users can add their own Partial Differential Equations (PDEs) within the COMSOL Multiphysics interface.

## Comments

Murilo Pessoa de OliveiraApril 13, 2013 11:17 pmnatural convection.mph – Where can I find this template to download?

I would like to replace the fluid and include the AIR but also consider the effects of thermal radiation in the annular space, How to do this?

Phil KinnaneApril 16, 2013 1:35 pmHi Murilo, the model here is a little out of date and probably wouldn’t be appropriate for the latest release. Also, it would be very difficult to include the radiation physics using the underlying equations. This is instead supported by the Heat Transfer Module

Amin ParviziOctober 2, 2013 9:23 amGreetings,

As a matter of fact, I have two Poisson equations with two different source term ( D^2 =f1 and D^2=f2 , D^2 is Laplacian) in 2D and , I do not know what is the boundary condition. Would it possible to use the equation based modeling in Comsol to solve this kind of equations?

Best Regards

Phil KinnaneOctober 7, 2013 10:51 amHi Amin,

Yes, of course you do need to know the boundary conditions, but once you figure that out, you certainly can solve two coupled Poisson equations in COMSOL.

Nor SyamimiOctober 11, 2013 4:01 amhi, i am currently doing on solid mechanics model..i’m having trouble to calculate the line length of my model before and after deformation to calculate the object elongation. I am an beginner in comsol..

mimi

Ozgur TanerOctober 21, 2013 4:59 pmIs it possible to edit one of the coefficients as a second PDE’s dependent variable? For instance, changing ‘alpha’ in coefficient form as ‘u2′. In this case, does Comsol apply the nabla operator to both of the variables, or it only considers alpha as a coefficient (which will be the value of u2 in this case)? Thanks in advance.

Nishanth MehanathanJanuary 22, 2014 12:05 amHi How can I include curl of a vector in the PDE …

Hassanein MobarekOctober 24, 2014 6:28 pmHi,

I have a question regarding to create my own PDE in COMSOL, I know that I have to use one of three templates available in COMSOL but still I don’t know how to transfer my high nonlinear equation into one of the equation templates.

Could anyone please help

Regards

Phil KinnaneOctober 27, 2014 8:57 amHi Hassanein,

You may want to check out the following blogs that also talk about the subject:

http://www.comsol.com/blogs/solving-algebraic-field-equations/

http://www.comsol.com/blogs/equation-based-modeling-a-custom-model-of-a-beating-heart/

http://www.comsol.com/blogs/understanding-traffic-congestion-via-equation-based-modeling/

http://www.comsol.com/blogs/modeling-viscous-fingering-equation-based-modeling/

Failing that, I suggest that you make an attempt and, if this doesn’t solve, then send your attempt to the Support team (support@comsol.com) to see whether they can help you.

Best regards,

Phil