[Libmesh-users] tensor calculation

[li p. <li...@ya...>]

Dear friends,
I have again on mathematic question, which I can solve
by myself. Can anyone tell me how to transform the
following three terms

div ( delta_ij*delta_kl*U_lk ) + 
div ( delta_ik*delta_jl*U_lk ) +
div ( delta_il*delta_jk*U_lk )

into:
grad(div(U)) + laplace(U) + div(grad(U))
where,
delta_ij: Kronecker delta
U_lk partial differential of U  l,k=1,2,3

This has nothing to do with libmesh. But I really want
to understand it.

thanx

pan

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