On 02/08/2017 01:15 PM, Jaekwang Kim wrote:
I am using deal-ii to analyze Non-newtonian fluids, which varies viscosity.
For example, my viscosity eta is function of (u) field. I am solving
this with iteration method.. (Picard)
After coding, I am testing my code with method of manufacture.
For squared domain, I implemented all boundary condition with my assumed
solution and impose source term also to numerically generate my assumed
solution
however, the problem I got is.... also follow
While my velocity field is qualitatively similar to manufactured solution,
the pressure field is not following the exact form as seen below figure.
It is very strange that......I can approach u-soltution form while my
pressure does not....
In addition , any mesh refinement would not make more accurate solution
now.
If you were me, what would you check more to find out what is problem?
I would make the problem simpler. Do you get the right solution if you
have a constant viscosity? If you iterate, do you get the solution after
one iteration?
I will also note that your manufactured solution is symmetric, but your
computational solution is not. This provides you with a powerful way
because you don't actually need to look at the convergence, it's enough
to check that on a *coarse* mesh the solution is *symmetric*. It may be
that solution is already non-symmetric on 1 cell, or on a 2x2 mesh -- in
which case you already know that something is wrong. The question then
is why that is so -- is your rhs correct, for example?
Best
W.
--
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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