[petsc-users] Removing rigid body motion using Null Space

[Hom Nath Gharti]

Dear all,

After searching old mailing lists, it appears that the rigid body
motion can be removed using Null Space features in PETSc.
Unfortunately, I could not successfully implement this to a simple
elastostatic problem. I have an unconstrained sphere and I need to
compute displacement field due to a point load on the surface.

I tried:
call MatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,0,nullspace,ierr)
call MatSetNullSpace(Kmat,nullspace,ierr)
call MatNullSpaceRemove(nullspace,bvec,PETSC_NULL_OBJECT,ierr)
call MatNullSpaceDestroy(nullspace,ierr)

But the solution did not converge! Any help/hint would be greatly appreciated.

Best,
Hom Nath