# Discussion Forum

## Number of degrees of freedom solved for: 96195

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Paolo Tricerri

August 14, 2012 2:00pm UTC

Number of degrees of freedom solved for: 96195

Dear Sirs,

I am trying to understand from where the number 96195 comes from.

In particular, the mesh I am considering is a tetraedral mesh of a rectangular domain in 3D ( width = 5 cm, depth = 1.5 cm, height = 0.35 cm). The mesh, according to the mesh statistics the domain discretization is made of:

Prism elements: 6600
Triangular elements: 264
Edge elements: 276
Vertex elements: 8

I am using nearly-incompressible model for the material, there a mixed formulation is used to solve the problem and the pressure field is computed (which is not specified but since I use quadratic polynomial functions, it could be P1).
According to the formula presented in www.comsol.com/support/knowledgebase/875/ the number of nodes should be 6600*1.4 = 9240 and the DOFs (for the displacement) = 9240*3 = 27720. Adding the DOFf for the pressure (which is P1) we do not get 96195.

As someone an explanation for the number of DOF???

Many thanks,

Paolo

Ivar Kjelberg

August 14, 2012 8:28pm UTC in response to Paolo Tricerri

Re: Number of degrees of freedom solved for: 96195

Hi

Comsol uses higer order discretization on the elements, so you get more DoFs through tha (check the KB and the doc)t,and you should check how many depedent variables you have, some BC add local dependent variables too

--
Good luck
Ivar

Paolo Tricerri

August 16, 2012 8:21am UTC in response to Ivar Kjelberg

Re: Number of degrees of freedom solved for: 96195

Many thanks!

Have a nice day.

Paolo.

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