Direct numerical simulations (DNS) are carried out to study the laminar stability properties of an effusioncooled adiabatic flat-plate boundary layer at Mach 6. Through four aligned rows of holes, cold gas is blown into the boundary layer at the wall and background disturbances are excited at the wall upstream of the holes. Two cases are compared, with small and large spanwise spacing of the ho...

Controlled laminar turbulent transition of a D boundary layer ow caused by localized surface nonuniformities is investigated by means of spatial direct numerical simulations DNS based on the complete incompressible D Navier Stokes equations and a combined th order compact Finite Di erence spanwise Fourier spectral scheme The considered laminar spanwise invariant at plate base ow is a model of t...

Biologists have shown that bat wings contain distributed arrays of flow-sensitive hair receptors. The hair receptors are hypothesized to feedback information on airflows over the bat wing for enhanced stability or maneuverability during flight. Here, we study the geometric specialization of hair-like structures for the detection of changes in boundary layer velocity profiles (shapes). A quasi-s...

Boundary-layer theory is crucial in understanding why certain phenomena occur. We start by reviewing steady and unsteady separation from the viewpoint of classical non-interactive boundary-layer theory. Next, interactive boundary-layer theory is introduced in the context of unsteady separation. This discussion leads onto a consideration of largeReynolds-number asymptotic instability theory. We ...

Numerical simulations demonstrate that laminar breakdown in a boundary layer induced by the secondary instability of two-dimensional Tollmien-Schlichting waves to threedimensional subharmonic disturbances need not take the conventional lambda vortex/highshear layer path. J_ 1This research was supported by the National Aeronautics and Space Administration under NASA Contract No. NASl-18605 while...

This paper investigates the characteristics of wall pressure fluctuations in naturally developing boundary layer flows on axisymmetric bodies experimentally. The axisymmetric body has a modified ellipsoidal blunt nose. Flush-mounted microphones are used to measure the wall pressure fluctuations in the boundary layer flow over the body. The measurements are performed in a low noise wind tunnel. ...

Thermal transport at the interface between Lennard-Jones crystals is explored via non-equilibrium molecular dynamics simulations. The vibrational properties of each crystal are varied by changing the atomic mass of the crystal. By applying a constant thermal flux across the two-crystal composite system, a steady-state temperature gradient is established and thermal boundary conductance at the i...

This article presents the computation of a set of control parameters for the deterministic prediction of laminar boundary-layer instabilities induced by an imposed unsteady shock interaction. The objective of the study is exploratory in nature by computing a supersonic flight environment for flow over a blunt body and the deterministic prediction of the spectral entropy rates for the boundary l...

A novel numerical scheme has been developed to simulate high speed viscous flows in complex geometries using unstructured grids. A characteristic–filter based shock capturing scheme is applied as a corrector step to a non–dissipative predictor scheme. This algorithm is being used to study shock turbulent boundary layer interactions and this paper presents the results of a turbulent flow at Mach...