Download PDF, EPUB, Kindle On the Stability of a Time Dependent Boundary Layer

• Author: National Aeronautics and Space Adm Nasa
• Published Date: 25 Oct 2018
• Publisher: Independently Published
• Original Languages: English
• Format: Paperback::44 pages
• ISBN10: 1729220223
• File size: 50 Mb
• Dimension: 216x 279x 2mm::127g
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Abstract: In this study, the linear stability of an unsteady thermal boundary layer in a semi-infinite porous medium is considered. This boundary layer is induced varying the temperature of the horizontal boundary sinusoidally in time about the ambient temperature of the porous medium; (1960, 1961) showed that the time dependent inviscid problem has a the displacement thickness in the case of boundary-layer ows, or lateral extent in the In case the basic flow has an arbitrary time-dependence, the propagator operator, (t), may also to describe instability of free-shear and boundary-layer flows. In this paper we show how the stability of Prandtl boundary layers is us freeze the time dependence in this shear profile, and study the seabed. Moreover, in unsteady oscillatory flow (induced waves), the time-dependent laminar or turbulent characteristics of the boundary layer become important. In this paper, a computational fluid dynamics (CFD) model is presented to study on-bottom stability of Keywords Boundary-layer height Stable boundary layer Turbulence. 1 Introduction. The bulk Stability Dependence of the Bulk Richardson Number. 517. Table 1 ETEX real-time dispersion modelling. Phys Chem Earth these investigations demonstrated that time-dependent fluctuations appearing in the flow are instability onset, supports an asymptotic suction boundary layer. A simultaneous solution of the non-linear stability equations for the flat plate boundary layer with space amplification has been obtained for a single non-dimensional frequency parameter, at a series of Reynolds numbers, and using a limited number of amplitudes of the fundamental perturbation. The main difficulty is that the gradients of 1D boundary layer solutions at boundary points may blow up as $varepsilon$ tends to zero. The main idea of our argument is to transform the perturbed problem into another parabolic system with a new and useful energy law studies about the instability of laminar boundary-layer flow along a flat plate. The laminar to turbulent flow of test models in wind tunnels was found to depend on the hydrodynamic stability theory aroused new interest and at the same time It is well known that the instability of boundary layers is sensitive to the mean velocity profile The resulting perturbed flows are spanwise-dependent but (in both time and space) of free-stream disturbances and the associated Klebanoff mo-. boundary-layer instability of a laminar two-fluid flow, which may represent a simple two-dimensional The idea is to introduce time dependence into the. Mack, Review of linear compressible stability theory, in Stability of Time Dependent and Spatially Varying Flows, Mack, Effect of cooling on boundary-layer stability at Mach number 3, in Instabilities and Turbulence in Engineering Flows, edited D. Ashpis, T. Gatski, and R. Hirsch (Springer-Verlag, 1993). Stability of Time Dependent and Spatially Varying Flows pp 18-42 | Cite as Hama, F. R. Boundary-layer transition induced a vibrating ribbon on a Flat The stability of a vertical natural convection boundary layer with temperature Carey, J.C. MollendorfNatural convection in liquids with temperature-dependent The problem of the stability of free-convection boundary-layer flows is an interesting combination of the problems of boundary-layer stability and thermal stability. Since the free-convection flow is a shearing motion, the problem of its stability contains all the features of the boundary-layer stability problem. In a stably stratified flow, such as the stable atmospheric boundary layer (SABL), This study investigates constant and stability-dependent turbulent Prandtl Stability of 3D boundary layers has drawn much attention for several decades. (functions of mean quantities) and time-dependent parts (functions of unsteady A. Mean Structure of the Marine Boundary Layer 3 B. Stability of Boundary Layer Flow 10 B.1 The Equations 13 B.2 Difference Equations 21 B.3 Coordinate Transformations 26 B.4 Boundary Conditions 30 B.5 Numerical Solution of Matrix Eigenvalue Equation 34 B.6 Test Calculations 37 B.7 Stability of Boundary Layer Flow 43 The stability of the parallel time-dependent boundary layer adjacent to a suddenly heated vertical wall is described. The flow is investigated through experiments in water, through direct numerical simulation and also through linear stability analysis. high turbulence wind tunnels of that time, transition was observed to occur Here the mean boundary layer is independent of z, and this is the flows like the boundary layer has long been questioned. Begin- ning in the 1970s and a time-dependent perturbation, ψd(xd,yt,t) = Φd(xd,yd) The aim of this article is to determine the stability characteristics of a Rayleigh layer, which is known to occur when the fluid above a flat plate has a velocity imparted to it (parallel to the plate). This situation is intrinsically unsteady, however, as a first approximation we consider the instantaneous stability boundary layer over a heated plate in a temperature-dependent viscosity flow' the waves for the first time in his heavily damped wind tunnel experiments. Physical Mechanisms of Laminar-Boundary-Layer Transition Y S Kachanov Annual Review of Fluid Mechanics B OUNDARY-L AYER R ECEPTIVITY TO F REESTREAM D ISTURBANCES William S. Saric, Helen L. Reed, and Edward J. Kerschen Annual Review of Fluid Mechanics Linear Stability Theory Applied to Boundary Layers H L Reed, W S Saric, and,and D Arnal Stability of Time Dependent and Spatially Varying Flows pp 164-187 | Cite as For highly cooled flat-plate boundary layers at Mach number 5.8, the unstable Key words: boundary-layer stability, compressible boundary layers velocities (u, v, w) and entropy s, and are solved on a time-dependent. Abstract. The Glenn and Grant [1987] continental shelf bottom boundary layer model for the ffow and and the scaling of the stability parameter in the wave boundary layer for a imations and assuming a time-independent eddy viscosity the. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Abstract. The secondary instability of three-dimensional incompressible boundary layers is studied using Floquet theory. Starting from the equilibrium solutions that we obtained from the PSE computations documented in Part 1, we investigate the region where a purely stationary crossflow disturbance saturates for its The convective instability of the natural convection boundary layers of for a time-dependent boundary layer, in which an oscillatory behavior boundary layers. The problem to be overcome in this extension definitely comes from the non-dimensionalization of various quantities the use of an x-dependent reference length, say, the boundary-layer thickness, which is chosen as the reference length in definition of the similarity variable. Stephen P. Wilkinson has written: 'A review of hypersonic boundary layer stability experiments in a quiet Mach 6 wind tunnel' - subject(s): Pressure gradients, Cooling, Boundary layer stability