On 9/15/21 10:47 PM, Toddy Liu wrote:
Thank you very much for your reply and it really helps me. You explained
how to deal with the latter case (V'(u) . grad u, phi_i) and I've got
the point how to solve this. Addtionally. how about the former case
-(V(u), grad phi_i). Specifically, how to construct the vector V(u) and
then multiply with grad phi_i or to say fe_values.shape_grad(i,q_point)?
You perform the integral via quadrature, and so all you have to know is what
V(u)(x_q) = V(u(x_q))
which you evaluate in the same way as you did
sin(u(x_q))
in step-25 with the only exception that now V(u(x_q)) is a vector
(actually, a Tensor<1,dim>) instead of a scalar quantity.
Best
W.
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Wolfgang Bangerth email: [email protected]
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