Problem with boundary conditions for PDEPE

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Shubhanshu Agarwal
Shubhanshu Agarwal 2019-4-19
回答： Josh Meyer 2019-5-1
I'm trying to apply following boundary equations for 8 PDEs but the solver is assuming zero flux boundary conditions for all the PDEs at the left boundary.
pr= [-rad1;2-ur(2);0-ur(3);0-ur(4);0-ur(5);0-ur(6);0-ur(7);1-ur(8)];
qr = [((Tf2-Ti)/r);0;0;0;0;0;0;0];
ql = [((Tf2-Ti)/r);0;0;0;0;0;0;0];
pl = [rad2;2-ul(2);0-ul(3);0-ul(4);0-ul(5);0-ul(6);0-ul(7);1-ul(8)];
Is there anything wrong with the way I have specified the boundary conditions?

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Josh Meyer
Josh Meyer 2019-5-1
From the doc for pdepe,
"When m > 0 and a = 0, boundedness of the solution near x = 0 requires that the flux f vanish at a = 0. pdepe imposes this boundary condition automatically and it ignores values returned in pl and ql."
So if you are using a value of m greater than 0 (i.e. cylindrical or spherical problem symmetry), then the solver always enforces zero flux on the left boundary no matter what you specify.

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