The influence of boundary layer growth on the flow stability Blasius is analysed a rational, large Reynolds number, basis, for small disturbances fixed frequency. parallel-flow solution forms leading term and non-parallel effects emerge in consistent fashion from asymptotic expansions. Compared with previous, successive approximation, procedures, theoretical neutral curve obtained here much more affected by consequently shows somewhat improved agreement experimental observations, even though...

The variability in the volume transport of Florida Current at 27°N has been observed from voltage measured between a point 16 km east Jupiter Inlet, and Settlement Point, Grand Bahama Island by use an abandoned communications cable. is caused separation electric charges ocean that are crossing Earth’s magnetic field (motional induction), currents induced time varying ionospheric magnetospheric (geomagnetic bias cable-ocean contacts differences temperature, salinity electrochemical state...

A boundary layer flows over a flat plate which has on it small hump situated downstream of the leading edge. The description boundary-layer flow, based upon triple-deck structure, shows how presence generates an interaction between inviscid region just outside and viscous near hump. pressure force dominant in connexion local flow with main stream develop together are self-perpetuating, both remain primary significance for wide range sizes, even buried well inside layer. By consideration...

The unsteady boundary-layer flow produced by a two-dimensional vortex in motion above an infinite plane wall otherwise stagnant fluid is considered the limit of Reynolds number. This study part continuing investigation into nature physical processes that occur near surface transitional and fully turbulent boundary layers. adverse pressure gradient due to leads development zone recirculation viscous surface, then focuses rapidly toward eruption along band which very narrow stream wise...

For high Reynolds numbers the planar nonlinear stability properties of boundary layers, as governed first by triple-deck interaction, are discussed theoretically. When a disturbance relatively frequency is introduced or distance downstream increases in Blasius case characteristic length scale shortens. An account given possible progress such disturbance, from an initially small Tollmien-Schlichting state, through weakly stage that does not interrupt amplitude growth, and thence into fully...

The nonlinear stability of small disturbances to the Blasius boundary layer is considered within a rational, high Reynolds number (Re), framework for complete range disturbance sizes properties amplitude depend crucially on size δ relative inverse powers Re. Most attention given largest that can be dealt with, near lower branch neutral curve, namely = O(Re -1/8), which effects yield supercritical equilibrium amplitudes. smaller are profoundly affected by ( inter alia) non-parallel flow...

The field of fluid mechanics is rapidly advancing, driven by unprecedented volumes data from experiments, measurements, and large-scale simulations at multiple spatiotemporal scales. Machine learning (ML) offers a wealth techniques to extract ...Read More

A metalorganic chemical vapor deposition process for preparing c-axis-oriented ZnO films in a simple system of the type commercially available SiO2 is described. The resulting layers are highly uniform thickness and adhere to variety substrates. Film properties structure described briefly.

This theoretical work shows formally that unsteady interactive boundary layers can break up within a finite time by encountering nonlinear localized singularity. The theory is an extension of, and guided to large extent by, Brotherton-Ratcliffe Smith's (1987) on special case. Two major types of singularity are proposed, "moderate" type yielding singular pressure gradient "severe" associated with discontinuity. Each produces response in the skin friction case wall-bounded flows. present...

The work, addressing subsonic, supersonic and hypersonic boundary-layer instability, is motivated by the need for more understanding of compressible transition at high global Reynolds numbers Re. In case, so-called 'first modes' instability found/suggested previous Orr-Sommerfeld computations can be identified as triple-deck oblique ones, directed outside local wave-Mach-cone directions. Less modes inside are not form since they substantially affected non-parallel flow effects. maximum...

The unsteady boundary layer induced by the motion of a rectilinear vortex above an infinite plane wall is calculated using interacting boundary-layer methods. solution computed in Lagrangian variables since it possible to compute flow evolution accurately this formulation even when eruption starts evolve. Results are obtained over range Reynolds numbers, Re. For limit problem Re → ∞ (studied Part 1), singularity develops non-interacting at finite time. present results show that calculations...

The air cushioning effect in the gap between an almost inviscid body of water and a nearby solid wall (or another water) is studied theoretically found to depend on predominantly lubricating forces air, certain applications. situation which density viscosity are taken as small compared with those investigated. In this potential-flow dynamics couples lubrication behaviour leading nonlinear integro-differential system for evolution interface. numerical values main parameters investigated...

Numerical solutions of the Navier-Stokes equations are given for steady, two-dimensional, laminar flow an incompressible fluid through a channel with symmetric constriction in form semi-infinite step change width. The proceeds from steady Poiseuille velocity distribution far enough upstream wider part to corresponding downstream narrower and is assumed remain symmetrical about centre line channel. numerical scheme involves accurate efficient centred difference treatment developed by Dennis...

An analytical and numerical study is presented on the response of high Reynolds number flow when, starting from a fully attached state, it forced to gradually approach separation as certain critical parameter increased. The end near rounded leading edge particular problem considered, although application theory much wider. angle incidence. Goldstein singularity first appears only weakly, then attached‐flow concept can even admit small local bubble. As increases in strength, however, solution...

Journal Article SEPARATION OF JETS OR THERMAL BOUNDARY LAYERS FROM A WALL Get access F. T. SMITH, SMITH Mathematics Department, Imperial CollegeLondon Search for other works by this author on: Oxford Academic Google Scholar P. W. DUCK The Quarterly of Mechanics and Applied Mathematics, Volume 30, Issue 2, May 1977, Pages 143–156, https://doi.org/10.1093/qjmam/30.2.143 Published: 01 1977 history Received: 03 1976 Revision received: 15 July

The steady planar symmetric motion of an incompressible fluid, past a bluff body fixed in otherwise uniform stream, is considered for large Reynolds numbers Re. A laminar-flow structure proposed which consists primarily (a) the large-scale flow and (b) smaller, body-scale, flow. Here involves pair massive, effectively inviscid, recirculating eddies set up behind bounded by viscous shear layers. Each eddy has small constant vorticity its length width both increase linearly with Re, so that...

The three-dimensional interaction and evolution of a thin rotating body's motion within surrounding fluid is presented here. each shown to affect the other significantly through dynamic fluid–body interaction. consideration spatial effects time-dependent body are new features for this near-wall unsteady problem. non-linear formulated an inviscid incompressible several scenarios explored in which shape, rotation, studied. problem reduces solving Poisson's equation underbody planform, subject...

<title>Abstract</title> Lubricating fluid motion is analysed in the context of Stokes flow through a channel containing freely moving, relatively dense particle. The typical particle thickness finite fraction width, whereas longitudinal length scale larger, with having otherwise arbitrary shape. dynamics gaps are coupled motion. Analysis and numerical results show that direct ’impact’ can occur wall within time; however, strictly this represents onset impact, yielding new local physics....

In this theoretical and computational study of the flow a liquid layer, under influence surface tension gravity most notably, nonlinear equations governing an interaction between viscous effects tension, streamline curvature for limit large Reynolds numbers are derived. The aim is to make comparison predictions theory experiments Craik et al. on axisymmetric hydraulic jump. Such jump commonly encountered in everyday context initial filling kitchen sink, example, it found present work that...

Much of the recent analysis chaotic mixing has focused on utilizing tools and techniques imported from dynamical systems theory. However, most require detailed information about velocity field or fluid motion are restricted to conditions where ‘degree chaos’ is small. Symmetries provide a method without specific reference exact mathematical expressions. Symmetry concepts illustrated in terms prototypical system called eggbeater flow. Although family 32 different flows can be constructed,...

Recent controlled experiments by Kachanov &amp; Levchenko (1984) and others indicate that, during some slower kinds of transition to turbulence in boundary layers, three-dimensionality can come into play initially as a resonant-triad phenomenon, depending on the disturbance sizes present. The triad interaction, suggested theoretically boundary-layer context Craik (1971) others, is studied present work means multi-structured analysis for high characteristic Reynolds numbers. A...

The linear and weakly nonlinear stability of Poiseuille–Couette flow is considered for various values the relative wall velocity 2uw, An account given first asymptotic upper lower branches neutral curve (s), followed by their disappearance, as uw increased. Two main (and one minor) curves are found to exist smaller O(1) (or lesser) uw, then moderate none larger uw. cut-off at which each disappears determined, in case whole just below value determined closed form. Secondly, solutions...

The unstable and neutral modes of a compressible boundary-layer flow past an insulated flat plate are discussed in the limit infinite Mach number. These have been documented by Mack many asymptotic results derived here becoming evident his computations at finite values Of particular interest is existence vorticity mode for which wavenumber discontinuous function number but continuous M∞ → ∞. At large this most mode, expected to relevance also hypersonic when field no longer shock-free.

The stability of the Blasius boundary layer is studied theoretically, with aim fixing character upper branch neutral curve(s) and its dependence on non-parallel flow effects. Unlike most previous studies this work has a rational basis since, throughout, we consider linear structure for asymptotically large Reynolds numbers ( Re ). five-zoned quite complicated, more so than (discussed in Smith (1979 )) governing lower properties, but nevertheless it lends itself to systematic determination...