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1. Introduction
The unsteady nature of a wide range of fluid flows of practical importance has received considerable attention in recent years. In many applications, the ideal flow environment around the device is nominally steady, but undesirable unsteady effects arise either due to self-induced motions of the body, or due to fluctuations or non-uniformities in the surrounding fluid. Unsteady viscous flows have been studied rather extensively and all of the characteristic features of unsteady effects are now more or less familiar to fluid mechanists. Comprehensive reviews of the literature on unsteady forced convection boundary-layer flows are presented in [20] Riley (1975, [21] 1990), [24] Telionis (1979, [25] 1981), and [15] Ludlow et al. (2000). However, fewer studies have been concerned with the forced convection heat transfer aspects, see [19] Pop (1996).
The boundary-layer flow along a semi-infinite flat plate that is started impulsively from rest was first studied by [23] Stewartson (1951), [4] Hall (1969), [3] Dennis (1972), and others. Extending the work of [23] Stewartson (1951), [22] Smith (1967) considered the impulsive motion of a wedge and presented an approximate solution that is based on the momentum integral method. [17] Nanbu (1971) obtained numerical solutions of this problem, using a scheme similar to that of [4] Hall (1969), i.e. using three independent variables. [28] Williams and Rhyne (1980) formulated the problem of impulsively set into motion wedge type (Falkner-Skan) flows in a new set of scaled coordinates. Both the short-time solution and the solution for infinite time, the Falkner-Skan solution, were included in this new formulation of the problem. In addition, the new scaling reduced the region of integration from the traditional infinite region to a finite region, thus also reducing the time required for numerical computations. Numerical solutions for the forced convection thermal boundary layer produced by the sudden imposition of a constant temperature difference between the wedge and the fluid as the motion is started have been given by [27] Watkins Jr (1976). Very recently, [29] Xu and Pop (2008) have studied the unsteady boundary-layer flow past a wedge using the homotopy analytic method (HAM). The problem of a wedge impulsively set into motion and some associated heat transfer characteristics have been considered by [9] Harris et al. (2002, [10] 2008).
The...