On 02/15/2018 09:24 AM, jie liu wrote:
Setting 'a' equal or not equal to zero, it works when 'b' is equal to
zero (homogeneous Dirichlet boundary condition on the gradient).
Specifically, the convergence order of the solution is one order higher
than the element degree of the solution, and the convergence order of
the gradient is equal to or one order lower than the element degree of
the gradient.
However, when 'b' is not equal to zero ( inhomogeneous Dirichlet
boundary condition on the gradient), it does not work for the gradient,
i.e. the convergence order of the solution is still one order higher
than the element degree, but the convergence order of the gradient keeps
0.5 for different elements.
Could anyone explain this? Thank you.
When you plot the error as a piecewise constant function with one value
per cell, is the error localized at a boundary cell?
Best
W.
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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