In science and technology problems with free and/or moving boundaries are encountered very often, in which the domain boundary and/or domain interface are unknown a priori and must be determined as a part of the solution. A problem with unknown boundary/interface is called free-or moving-boundary one, depending on that it is a steady-state problem with the boundary at rest or a time-dependent problem with moving boundary respectively. Typical examples of free/moving boundary problems in fluid dynamics and heat transfer are: solid boundaries in inverse and hybrid problems, shocks, free vortex sheets, Stefan problem in heat conduction, free surface flow, cavitated flow boundary ,seepage flow boundary, solid-fluid interface in aeroelasticity and so on[1]. The presence of these unknown boundaries is one of the important origins of nonlinearity of the problem and makes it much more difficult to solve either analytically or numerically.