form (const space V, const space& V, "2D_D");
Assembly the form associated to the div(2D(.)) components of the operator on the finite element space V:
/ | a(u,v) = | 2 D(u) : D(v) dx | / Omegawhere
1 ( d ui d uj ) Dij(u) = - ( ---- + ---- ) 2 ( d xj d xi )This form is usefull when considering elasticity or Stokes problems.
Here is an example of the vector-valued form:
geo omega ("square"); space V (omega, "P2", "vector"); form a (V, V, "2D_D");Note that a factor two is here applied to the form. This factor is commonly used in practice.