Effects of Slip on the Flow Characteristics of Laminar Flat Plate Boundary-Layer

Abstract

A uniform stream of viscous fluid flowing past a flat plate with slip at the fluid-plate interface is considered. The aim of this investigation is to examine the effects of slip at the wall on the laminar boundary-layer flow characteristics. For this purpose, an analytical and a computational study were conducted. The analytical study is based on the Blasius similarity solution for laminar boundary-layer flow past a flat plate. In the computational study, the flow over a flat plate is modeled and solved (using FLUENT) by dividing the computational domain into small control volumes and discretizing and solving the governing equations around these control volumes. The slip at the fluid-solid interface is accounted for by the Navier boundary condition (NBC). Three cases are considered, wherein the slip boundary condition is incorporated in three different ways, i.e., by specifying the slip length, or the slip velocity, or by assuming the slip length to be a function of shear rate. The flow characteristics are evaluated for different amounts of slip. The wall shear stress, the skin-friction coefficient, and the drag coefficient decrease by about 38% when the nondimensional slip length is increased from zero (noslip) to 2. The boundary-layer thickness, the displacement thickness, and the momentum thickness also decrease with increase in slip. The reduction in displacement thickness is much greater (about 68%) than the boundary-layer thickness or the momentum thickness. An excellent agreement between the analytical and computational results is noticed.