Partial differential equations of the parabolic type are commonly encountered in the study of heat conduction, gas expansion, and electromagnetic field propagation. One of the independent variables in these problems is time, typically denoted by t. Thus, parabolic equations often describe physical processes that evolve over time, known as unsteady physical processes. There are three main types of well-posed problems for parabolic equations: the pure initial value problem, the initial-boundary value problem on a semi-unbounded domain, and the initial-boundary value problem on a bounded domain.