>At 2012-11-04 21:52:23,"Mark F. Adams" <mark.adams at columbia.edu> wrote:
>Just to add to Jed and Matt's comments:
>1) What are your equations (I really don't care what physics you are modeling,
>its the equations that we see). Is is a scalar div (alpha(x) grad ) u?
The linear system Ax=b is resulted from the finite element discretization. It
is a algebraic equation, based from a elliptic equation, my opinion.
>2) Try using hyper (-pc_type hyper -pc_hypre_type boomeramg). Look at
>"PCApply 448", this should be like 10-20. Configure your systems
>with -->download-hyper=1 if you do not have it.
>3) Why do you say it is ill conditioned? Stretched grids? large jumps in
>material coefficients? Why do you think it is illoconditioned?
Pragmatic geotechnical problems often involve materials with highly varied
material zones, such as in soil-structure interaction problems or soil-water
coupled problems.([1]summary;[2-4])
Reference:
[1]Krishna Bahadur Chaudhary. Preconditioners for soil-structure interaction
problems with significant material stiffness contrast[D].
[2]S.H.Chan. A modified Jacobi preconditioner for solving ill-conditioned
Biot's consolidation equations using symmetric quasi-minimal residual
method.International journal for numerical and analytical methods in
geomechanics[J].
[3]Kok-Kwang Phoon. Iterative solution of large-scale consolidation and
constraint finite element equations for 3D problems.International e-Conference
on
Modern Trends in Foundation Engineering[J].
[4]Massimiliano, etc. Ill-conditioning of finite element poroelasticity
equations. International Journal of Solids and Structures[J].
Thanks.
Jim
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