This communication presents the results and conclusions of an experimental study of the near-separation region of a single-stream shear layer. The momentum thickness at separation (x=0) was θ0 = 9.6mm, with Reynolds number Reθ =4650. Boundary layer separation was caused by a sharp 90◦ edge. Detailed singleand multipoint measurements of the velocity field were acquired at the streamwise location...

In this paper, we study the influence on the ring-like vortex structure in MVG controlled supersonic ramp flow by different inflow conditions. In front of the MVG, three turbulent inflow profiles with different boundary layer thickness are generated as the inflow. From the shape factors, we can see that these inflows in front of the MVG are fully developed turbulent. It is found that the inflow...

We consider the Navier-Stokes equations for viscous compressible heat-conducting fluids with cylindrical symmetry. Our main purpose is to study the boundary layer effect and convergence rates as the shear viscosity μ goes to zero. We show that the boundary layer thickness and a convergence rate are of order O(μ) with 0 < α < 1/2 and O( √ μ) respectively, thus extending the result for isentropic...

The influence of the boundary layer properties on the heat transport in turbulent thermal convection is experimentally investigated in a cell with a rough bottom plate. It is shown that the standard 2/7 exponent of the convective heat flow dependence on the Rayleigh number, usually observed in cell with smooth boundaries, increases if the roughness has power law distributed asperity heights and...

We study the inviscid limit problem of the incompressible flows in the presence of both impermeable regular boundaries and a hypersurface transversal to the boundary across which the inviscid flow has a discontinuity jump. In the former case, boundary layers have been introduced by Prandtl as correctors near the boundary between the inviscid and viscous flows. In the latter case, the viscosity ...

Functional additives, particularly extreme pressure and antiwear additives, in formulated oil will compete to adsorb and function in tribological contacts. A low-polarity commercial base oil, poly-α-olefin (PAO), blended with zinc dialkyl dithiophosphates (ZDDP) has been studied. The tribological performance was evaluated using a ball-on-disk test rig under mixed rolling-sliding conditions in t...

The existence of a critical roughness height for outer layer similarity between smooth and rough wall turbulent boundary layers is investigated. Results are presented for boundary layer measurements on flat plates covered with sandgrain and woven mesh with the ratio of the boundary layer thickness to roughness height /k varying from 16 to 110 at Re =7.3 103–13 103. In all cases tested, the laye...

Here we describe the application of a multiple camera planar particle image velocimetry (PIV) measurement to achieve a large field of view (FOV) in a high Reynolds number turbulent boundary layer. Measurements are performed over a FOV of 0.8m × 0.5m (2.25δ × 1.4δ, where δ denotes the boundary layer thickness) in the streamwise and wall-normal directions respectively in a turbulent boundary laye...

This paper presents a formalism to automate portions of the traditional scaling procedure. This formalism, called here Order of Magnitude Scaling (OMS), captures essential components of the governing equations into a set of matrices and arrays amenable to computer implementation using standard linear algebra tools. This approach is valid and specially useful for large systems of multicoupled eq...

This paper concerns steady, high-Reynolds-number flow around a semi-infinite, rotating cylinder placed in an axial stream and uses boundary-layer type of equations which apply even when the boundary-layer thickness is comparable to the cylinder radius, as indeed it is at large enough downstream distances. At large rotation rates, it is found that a wall jet appears over a certain range of downs...