SNES and internar variables

Lukasz Kaczmarczyk likask at
Wed Sep 30 10:15:43 CDT 2009


I like to use  SNES to solve nonlinear system of equations. For my  
problem, I have to update some internal variables for computed newtons  
increments of primary unknowns, before I update residual (right hand  
side) and Jacobian. I found function SNESSetUpdate which is called at  
the beginning o every iteration. But I am not sure enough if that  
function is proper for updating internal variables. Can You advise me  
if it is right to use internal variables, f.e. increments of plastic  
strain at gauss points.

Such problems exist  in solid mechanics when increment of plastic  
strain and plastic multiplayer have to be computed. Another example is  
for hybrid/mixed FE discretisation having some variables approximated  
with C(-1) continuity. Unknowns associated to C(-1) continuos  
approximations  can be statically condensed , see attached file. As a  
results at each iteration step increments for statically condense  
variables have to be updated.

Lukasz Kaczmarczyk

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