[petsc-users] [petsc-maint] How to impose boundary conditions using DMDA

[Fengwen Wang]

Yes.  I would like to a rotational BCs(Twist bcs).


Such a boundary is needed to reduce the computational domain.


Thanks lot


Best regards

Fengwen




____________________________________________________
Senior Researcher
Department of Mechanical Engineering, DTU
Nils Koppels Allé
Building 404
2800  Kgs. Lyngby
fwan at mek.dtu.dk
________________________________
From: Lawrence Mitchell <wence at gmx.li>
Sent: Monday, October 29, 2018 1:17:34 PM
To: Matt Knepley
Cc: Fengwen Wang; PETSc; PETSc
Subject: Re: [petsc-users] [petsc-maint] How to impose boundary conditions using DMDA



> On 29 Oct 2018, at 10:56, Matthew Knepley <knepley at gmail.com> wrote:
>
> You can certainly map the right edge to the top edge (its topologically a square again), but that
> mapping is not smooth, and I do not know how you would make a global basis for the approximation space.

Yeah, I thought this was topologically just a cone, but that would have:

u(x=1) = -v(y=1)

and

v(x=1) = u(y=1) (note matching sign).

So if you wanted the v(x=1) = -u(y=1) there would be a twist somehow, and then a discontinuity in the mapping.

Lawrence
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