[petsc-users] Solving with SNES

[Matthew Knepley]

On Sat, Nov 12, 2011 at 5:50 PM, behzad baghapour <
behzad.baghapour at gmail.com> wrote:

> So, I am solving the Euler equations (inviscid compressible flow) using
> discontinuous Galerkin method:
>
> M (dQ/dt) = R,
>
> R = nonlinear residual,
> M = mass matrix,
>
> Implicit procedure:
> F = M*(Q^(n+1)-Q^n)/DT - R,
> dF/dQ=J=M/DT-dR/dQ,
> Newton => Q^(n+1) = Q^n - (dF/dQ)^(-1) F ( with proper preconditioning )
>
> The nonlinear residual and Jacobian matrix are evaluated with a face-based
> method. Two integrals are involved (the effect of element internal
> connections and face flux connections). All of my calculations of flow
> states are solved and stored in arrays of objects called elements.So my
> residual and Derivative of residual routines are developed based on the
> element (and face) objects. Then it is better for me to keep them when
> using petsc as a nonlinear solver.
>

Pass your mesh data structure in using the ctx argument for your residual
and Jacobian evaluation routines.

   Matt


> Hope these make any help.
> Thanks,
> Behzad
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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