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Direct numerical simulation (DNS) is used to study the evolution of a boundary layer that was laminar initially followed by separation and then reattachment owing to generation of turbulence. This creates a closed region of recirculation, known as the laminar-separation bubble. The present simulation emulates the flow environment encountered in a modern LP turbine blade, where a laminar separat...

In an earlier paper in Entropy [1] we hypothesized that the entropy generation rate is the driving force for boundary layer transition from laminar to turbulent flow. Subsequently, with our colleagues we have examined the prediction of entropy generation during such transitions [2,3]. We found that reasonable predictions for engineering purposes could be obtained for flows with negligible strea...

This paper details a joint numerical and experimental effort to investigate a transition process in a laminar separation bubble, with the emphasis being put on the numerical contribution. A laminar separation bubble is formed if a laminar boundary layer separates in a region of adverse pressure gradient on a flat plate and undergoes transition, leading to a reattached turbulent boundary layer. ...

The skin friction on a surface is a major concern by engineers. It is widely accepted that turbulent flow has higher friction than laminar flow due to the higher mixing in boundary layer. However, our new high order DNS found that the high friction is generated in a laminar zone in a transitional flow. Whenever the small length scales are generated, the velocity shear becomes very large in the ...

The problem of compressible boundary-layer laminar flow of a particulate suspension over a semi-infinite fiat plate is solved numerically using the finite-difference methodology. The mathematical model employed includes such effects as particle-phase viscous stresses, variable position-dependent particle slip coefficient, and general power-law viscositytemperature and thermal conductivity-tempe...

Numerical results are presented for the shock-boundary layer interactions in a hypersonic flow over a sharp leading edge compression corner. In this study, a second- order Godunov type scheme based on solving a Generalized Riemann Problem (GRP) at each cell interface is used to solve thin shear layer approximation of laminar Navier-Stokes (N-S) equations. The calculated flow-field shows general...

The computation of boundary-layer properties and laminar-to-turbulent transition location is a complex problem generally not undertaken in the context of aircraft design. Yet this is just what must be done if an aircraft designer is to exploit the advantages of laminar flow while making the proper trade-offs between inviscid drag, structural weight and skin friction. To facilitate this process,...