In Section 5–3 we considered one-dimensional heat conduction and assumed
heat conduction in other directions to be negligible. Many heat transfer problems
encountered in practice can be approximated as being one-dimensional,
but this is not always the case. Sometimes we need to consider heat transfer in
other directions as well when the variation of temperature in other directions
is significant. In this section we will consider the numerical formulation and
solution of two-dimensional steady heat conduction in rectangular coordinates
using the finite difference method. The approach presented below can be extended
to three-dimensional cases