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
Citations
More filters
Journal ArticleDOI
Nonlinear Stability Analysis of Boundary Layers by using Nonlinear Parabolized Stabiltiy Equations
Donghun Park,Seung-O Park +1 more
TL;DR: In this article, Nonlinear Parabolized Stability Equations (NSPE) is used to analyze the stability of a nonlinear region in transition process with low computational cost compared to Direct Numerical Simulation (DNS).
Computational Laminar-to-Turbulent Transition Physics of Complex Three-Dimensional Hypersonic Flow Fields
Abstract: Boundary-layer stability and laminar-to-turbulent transition have been studied for decades in various flows. Many useful computational techniques have emerged for basic research, but only a few of these techniques have evolved into engineering tools. Furthermore, the basic research has moved from flat plates to BOLT and HIFiRE-5, rather complex geometries. As the basic research community begins to move toward more realistic engineering designs, there seems to be an opportunity to reassess the applicability of basic research computational techniques to engineering. BOLT and HIFiRE-5 are the focus of this dissertation. The goal is to use the parabolized stability equations and spatial BiGlobal theory to understand key parts of their transition processes. It is shown that these geometries are stationary-crossflow dominant. Furthermore, the power and utility of the nonlinear parabolized stability equations is shown here and shows that it can be a key partner with direct numerical simulations and experiments toward the understanding and modeling of the laminar-to-turbulent transition problem, and it is proposed that this technique has evolved quite nicely and can be used for real application. The parabolized stability equations are used for primary instability analysis and spatial BiGlobal theory is used for secondary instability analysis. The stationary-crossflow instability and its secondary instabilities are the focus, but other instabilities are examined. A physics-based technique to model the heating rates of nonlinearly developing stationary crossflow is proposed. Furthermore, it is demonstrated that coupling nonlinear parabolized stability equations with spatial BiGlobal theory could provide a generalized technique to predict transition onset in flows with stationary crossflow as the dominant mechanism. The transition onset location is predicted by the location of the secondary instability neutral point. Moreover, the observed amplification of the secondary instabilities could potentially be the predictor for breakdown to turbulence. There is a strong emphasis on validation with ground and flight tests and verification with direct numerical simulations. The goal is that these results will provide insight for future computational, ground, and flight work.
Proceedings ArticleDOI
Longitudinal structures in boundary layers and their resonance nature
TL;DR: In this paper, Grosch et al. showed that the damping degree of perturbations down a flow depends on a wave number in the lateral direction poorly, and that the optimal values of the wave number are the ones in which perturbation damped down by a stream the most poorly.
Control of Stationary and Traveling Cross-Flow Modes in a Mach 6 Boundary Layer Using Passive Patterned Roughness and Unsteady Plasma Excitation
TL;DR: Arndt et al. as mentioned in this paper investigated the effect of passive surface roughness, consisting of indentations (dimples) that were evenly spaced around the cone at an axial location that was just upstream of the linear stability neutral growth branch for stationary cross-flow modes.
New Multi-Layer Compact High-Order Finite Difference Methods with Spectral-Like Resolution for Compressible Flow Simulations
TL;DR: Bai et al. as mentioned in this paper developed and analyzed new very high-order numerical methods with spectral-like resolution for flow simulations on structured grids, with focus on smooth flow problems involving multiple scales.
References
More filters
Book
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.