The development of finite difference formulation of boundary nodes in two-
(or three-) dimensional problems is similar to the development in the onedimensional
case discussed earlier. Again, the region is partitioned between
the nodes by forming volume elements around the nodes, and an energy balance
is written for each boundary node. Various boundary conditions can be
handled as discussed for a plane wall, except that the volume elements
in the two-dimensional case involve heat transfer in the y-direction as well as
the x-direction. Insulated surfaces can still be viewed as “mirrors, ” and the