Direct numerical simulation was used to study the formation and growth of a hairpin vortex in a at-plate boundary layer and its later development into a young turbulent spot. Fluid injection through a slit in the wall triggered the initial vortex. The legs of the vortex were stretched into a hairpin shape as it traveled downstream. Multiple hairpin vortex heads developed between the stretched l...

The relaxation of a shear flow (the process of an equilibrium state recovery) caused by the presence of a disturbance source such as a wall fence, roughness elements or obstacle in a turbulent boundary layer is a slow process which can not be predicted, at least accurately, even on the basis of current turbulence models. Previous investigations [1 – 3] are devoted to the study of the process of...

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-...

one of the popular and well known models in boundary layer that is implemented in most of the operational and familiar models is the mellor-yamada model of atmospheric boundary layer. one reason that this model is so popular is its ability in simulations and exposing of different phenomena in the boundary layer. this model has been constructed based on second order closure hypothesis. beside al...

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 new finite volume algorithm has been developed to solve a variety of flows by using large eddy simulation and direct numerical simulation. This finite volume algorithm was developed using a dual time stepping approach with a preconditioning technique and a new factorization implementation. The method takes the advantage of pressure-based and density-based meth­ ods. Thus, it provides an effic...

The impact of shock waves on supersonic cooling films is studied using large-eddy simulations (LES). A laminar cooling film is injected through a slot at a Mach number Mai = 1.8 into a fully turbulent boundary layer at a freestream Mach number Ma∞ = 2.44. The cooling film is disturbed by oblique shock waves at deflection angles of 5° and 8° at two downstream positions of the slot. At shock impi...

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...