Journal ArticleDOI
Boundary-layer receptivity to freestream disturbances
TLDR
The boundary-layer receptivity to external acoustic and vortical disturbances is reviewed in this article. But, the authors do not consider the effects of external acoustic or vortic disturbances on the boundary layer.Abstract:
The current understanding of boundary-layer receptivity to external acoustic and vortical disturbances is reviewed. Recent advances in theoretical modeling, numerical simulations, and experiments are discussed. It is shown that aspects of the theory have been validated and that the mechanisms by which freestream disturbances provide the initial conditions for unstable waves are better understood. Challenges remain, however, particularly with respect to freestream turbulenceread more
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Journal Article
Computations for laminar flow control in swept-wing boundary layers.
TL;DR: In this article, the laminarization of a swept-wing boundary layer by the introduction of passive spanwiseperiodic discrete roughness elements near the leading edge is modeled by linear stability theory without curvature (LST) and nonlinear parabolized stability equations (NPSE).
Journal ArticleDOI
Interaction of Stationary Disturbances with Tollmien—Schlichting Waves in a Supersonic Boundary Layer
S. A. Gaponov,N. M. Terekhova +1 more
TL;DR: In this article, the authors studied the effect of stationary streaks on the growth of the Tollmien-Schlichting wave in the flat-plate boundary layer at the freestream Mach number M = 2.
Journal ArticleDOI
Tendency to occupy a statistically dominant spatial state of the flow as a driving force for turbulent transition
TL;DR: In this article, a simple analytical model that treats the flow as a collection of localized spatial structures, each of which consists of elementary cells in which the behavior of the particles (atoms or molecules) is uncorrelated was proposed.
Posted Content
The role of microscopic fluctuations in transition prediction
TL;DR: In this article, microscopic fluctuations are shown to provide just the right amount of initial disturbances to match the predictions of linear stability theory. But they require the presence of an external source of disturbances that get amplified by an essentially linear mechanism up to the point where breakdown to turbulence occurs.
Proceedings ArticleDOI
Numerical Study of Freestream Waves Induced Breakdown in Hypersonic Boundary Layer Transition
Jia Lei,Xiaolin Zhong +1 more
TL;DR: In this paper, a new approach is introduced to simulate the hypersonic flow over blunt cone from laminar to the breakdown stage in transition, where disturbance waves are introduced into freestream instead of generating within the boundary layer.
References
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Stability and Transition in Shear Flows
TL;DR: In this article, the authors present an approach to the Viscous Initial Value Problem with the objective of finding the optimal growth rate and the optimal response to the initial value problem.
Journal ArticleDOI
A note on an algebraic instability of inviscid parallel shear flows
TL;DR: In this paper, it was shown that all parallel inviscid shear flows of constant density are unstable to a wide class of initial infinitesimal three-dimensional disturbances in the sense that, according to linear theory, the kinetic energy of the disturbance will grow at least as fast as linearly in time.
Journal ArticleDOI
Parabolized stability equations
TL;DR: Parabolized stability equations (PSE) have been used for aerodynamic design of laminar flow control systems as discussed by the authors, and they can be obtained at modest computational expense.
Journal ArticleDOI
Optimal disturbances and bypass transition in boundary layers
TL;DR: In this article, the authors used the steady boundary-layer approximation to calculate the upstream disturbances experiencing maximum spatial energy growth, which are numerically calculated using techniques commonly employed when solving optimal-control problems for distributed parameter systems.
Journal ArticleDOI
Reynolds number independent instability of the boundary layer over a flat surface : optimal perturbations
TL;DR: In this article, the dependence on initial conditions of the three-dimensional algebraic spatial instability of the Blasius boundary layer is examined by a recently developed method of receptivity analysis based on the upstream integration of adjoint equations.