My next step is to compute that way (static condensation of the
pressure) the navier-stokes equations with a Newton non linear solver,
as in step-57, but i do it on a simpler problem first (stokes).
Thus if i define
{R(u,p)} = {-2*div u + \nabla p -f},
I want to compute ||R(u,p)||.
Many thanks,
Yann
Le 10/15/2024 à 5:02 AM, Wolfgang Bangerth a écrit :
On 10/14/24 14:03, Yann Jobic wrote:
However, i don't know how to compute the residual ! It should be easy,
but i still haven't succeeded. If I extract the different submatrices of
the system matrix at the element level, i don't have the right type of
{U} to compute {P}:
{P} = -[Kpp]^{-1}*[Kpu]*{U}
The matrices are in FullMatrix format, and {u} is of type
std::vector<Tensor<1, dim>> if I'm using "get_function_values". Thus i
can't compute [Kpu]*{U}. I may have the nodal velocity values, but they
have to be ordered as [Kup], [Kpu], ...
Yann -- the term "residual" is used in different meanings in numerical
analysis. Can you define precisely what it is you want to compute?
Best
W.
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