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divergence of current density

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Hi

I want to find the divergence of current density using the expression div(J) , where J=(epsilonr-epsilon0)E to find the volume charge density (rho) using continuity equation. => div(J) = d/dt(rho)

if I try to find divergence using standard definition of divergence div(J)=(epsilonr-epsilon0)*(d(Ex,x)+d(Ey,y)+d(Ez,z)) I get large values due some numerical error for the finite mesh element size. Is there any other way to find divergence?

Thanks,

Amin

1 Reply Last Post 13 ago 2011, 14:00 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 13 ago 2011, 14:00 GMT-4
Hi

have you checked if the Exx Eyy ... are not already defined in COMSOL (I tend to forget how it was back in 3.5 ;), then you do not need to use the div() operator. Also check that you use 2nd or higher shape functions

--
Good luck
Ivar
Hi have you checked if the Exx Eyy ... are not already defined in COMSOL (I tend to forget how it was back in 3.5 ;), then you do not need to use the div() operator. Also check that you use 2nd or higher shape functions -- Good luck Ivar

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