4 Complications
Some problems can be solved analytically, but the solution procedure is so
complex and the resulting solution expressions so complicated that it is not
worth all that effort. With the exception of steady one-dimensional or transient
lumped system problems, all heat conduction problems result in partial
differential equations. Solving such equations usually requires mathematical
sophistication beyond that acquired at the undergraduate level, such as orthogonality,
eigenvalues, Fourier and Laplace transforms, Bessel and Legendre
functions, and infinite series. In such cases, the evaluation of the solution,
which often involves double or triple summations of infinite series at a specified
point, is a challenge in itself (Fig. 5–4). Therefore, even when the solutions
are available in some handbooks, they are intimidating enough to scare
prospective users away.