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Infinite expression, NDSolve
Posted:
Oct 16, 2012 3:25 AM


Dear All,
I am trying to use NDSolve to solve the heat equation for 1D radial flow in cylindrical coordinates, with the initial condition of a spatially constant temperature, and boundary conditions of zero flux at r=0 (axisymmetry) and a constant temperature at a radius of 1. Here is the code:
NDSolve[{D[T[r, t], t] == 1/r*D[r D[T[r, t], r], r], Derivative[1, 0][T][0, t] == 0, T[1, t] == 20, T[r, 0] == 0}, T, {r, 0, 1}, {t, 0, 10}]
Power::infy: Infinite expression 1/0. encountered. >>
Infinity::indet: Indeterminate expression 0. ComplexInfinity encountered. >>
Power::infy: Infinite expression 1/0. encountered. >>
Infinity::indet: Indeterminate expression 0. ComplexInfinity encountered. >>
NDSolve::ndnum: Encountered nonnumerical value for a derivative at t == 0.`. >>
I've tried using nonzero (i.e. very small values) for the initial time and in place of r=0 in the boundary condition, but to no avail. Any ideas?
Thanks!



