the current study presents the results of the aerodynamic noise prediction of the flow field around a naca 0012 airfoil at a chord-based reynolds number of 100,000 and at 8.4 degree angle of attack. an incompressible large eddy simulation (les) turbulence model is applied to obtain the instantaneous turbulent flow field. the noise prediction is performed by the ffowcs williams and hawkings (fw-...

A computational procedure is developed to determine initial instabilities within a three-dimensional laminar boundary layer and to follow these instabilities in the streamwise direction through to the resulting intermittency exponents within a fully developed turbulent flow. The fluctuating velocity wave vector component equations are arranged into a Lorenz-type system of equations. The nonline...

We discuss the existing theoretical prediction that convective disturbances traveling between 70% and 80% of the local surface speed are the most amplified within the boundarylayer flows over rotating cones and spheres. Although most experimental observations of such flows report stationary vortices excited by surface roughnesses, we note that Kobayashi & Arai [Laminar Turbulent Transition, IUT...

Especially for large amplitude initial disturbances so called vortices de velop during the non linear late stages of laminar turbulent transition Once formed they may persist as so called hairpin vortices well into the ensuing turbulent boundary layer This makes their study important for under standing transition and turbulence in wall bounded shear ows In Direct Numerical Simulations DNS as we...

Recent studies suggest a marked expansion of glacial ice across much of Gondwana beginning in the earliest Permian. Because expansion of glacial ice results in a lowering of sea level, the imprint of ice expansion should be evident worldwide as significant exposure event, hiatuses, or other evidence for sea level drop at or near the Pennsylvanian–Permian boundary. This literature review investi...

The unsteady Navier{Stokes equations ooer a large variety of instantaneous solutions even for rather simple boundary conditions once the relevant spatial and temporal scales of the problem at hand are adequately resolved. This is especially true for DNS (Direct Numerical Simulation) of laminar-turbulent transition, where an initially lam-inar ow, disturbed by some unsteady uctuations \breaks do...

Linear and nonlinear optimal control have been investigated in transitional channel and boundary layer flows. The flow phenomena that we study are governed by the incompressible Navier–Stokes equations and the main aim with the control is to prevent transition from laminar to turbulent flows. A linear model-based feedback control approach, that minimizes an objective function which measures the...

boundary layer growth and hence displacement thickness are the key factors in shock position over aerodynamical surfaces at transonic regimes. since boundary layer growth is a function of free stream reynolds number and also of the transition location, the free stream reynolds number and also the other parameters involved in the boundary layer growth and its transition location are determinant ...

The unsteady Navier Stokes equations o er a large variety of instantaneous solutions even for rather simple boundary conditions once the rel evant spatial and temporal scales of the problem at hand are adequately resolved This is especially true for DNS Direct Numerical Simulation of laminar turbulent transition where an initially lam inar ow disturbed by some unsteady uctuations breaks down in...