Nonlinear Stability of Unsteady Viscous Flow
Author | : Alric P. Rothmayer |
Publisher | : |
Total Pages | : 196 |
Release | : 1995 |
Genre | : Boundary layer |
ISBN | : |
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Author | : Alric P. Rothmayer |
Publisher | : |
Total Pages | : 196 |
Release | : 1995 |
Genre | : Boundary layer |
ISBN | : |
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 26 |
Release | : 2018-07-09 |
Genre | : |
ISBN | : 9781722455811 |
The stability of the flow of an incompressible, viscous fluid through a pipe of circular cross-section curved about a central axis is investigated in a weakly nonlinear regime. A sinusoidal pressure gradient with zero mean is imposed, acting along the pipe. A WKBJ perturbation solution is constructed, taking into account the need for an inner solution in the vicinity of the outer bend, which is obtained by identifying the saddle point of the Taylor number in the complex plane of the cross-sectional angle co-ordinate. The equation governing the nonlinear evolution of the leading order vortex amplitude is thus determined. The stability analysis of this flow to periodic disturbances leads to a partial differential system dependent on three variables, and since the differential operators in this system are periodic in time, Floquet theory may be applied to reduce this system to a coupled infinite system of ordinary differential equations, together with homogeneous uncoupled boundary conditions. The eigenvalues of this system are calculated numerically to predict a critical Taylor number consistent with the analysis of Papageorgiou. A discussion of how nonlinear effects alter the linear stability analysis is also given, and the nature of the instability determined. Shortis, Trudi A. and Hall, Philip Unspecified Center NAS1-19480; RTOP 505-90-52-01...
Author | : Trudi A. Shortis |
Publisher | : |
Total Pages | : 28 |
Release | : 1995 |
Genre | : |
ISBN | : |
Author | : Anthony James Sobey |
Publisher | : |
Total Pages | : |
Release | : 1978 |
Genre | : |
ISBN | : |
Author | : National Aeronautics and Space Adm Nasa |
Publisher | : Independently Published |
Total Pages | : 46 |
Release | : 2018-10-25 |
Genre | : Science |
ISBN | : 9781729219928 |
The stability has been investigated of the unsteady flow past an infinite flat plate when it is moved impulsively from rest, in its own plane. For small times the instantaneous stability of the flow depends on the linearized equations of motion which reduce in this problem to the Orr-Sommerfeld equation. It is known that the flow for certain values of Reynolds number, frequency and wave number is unstable to Tollmien-Schlichting waves, as in the case of the Blasius boundary layer flow past a flat plate. With increase in time, the unstable waves only undergo growth for a finite time interval, and this growth rate is itself a function of time. The influence of finite amplitude effects is studied by solving the full Navier-Stokes equations. It is found that the stability characteristics are markedly changed both by the consideration of the time evolution of the flow, and by the introduction of finite amplitude effects. Webb, J. C. and Otto, S. R. and Lilley, G. M. Unspecified Center NAS1-19480; RTOP 505-90-52-01
Author | : J. C. Webb |
Publisher | : |
Total Pages | : 41 |
Release | : 1994 |
Genre | : |
ISBN | : |
The stability has been investigated of the unsteady flow past an infinite flat plate when it is moved impulsively from rest, in its own plane. For small times the instantaneous stability of the flow depends on the linearised equations of motion which reduce in this problem to the Orr- Sommerfeld equation. It is known that the flow for certain values of Reynolds number, frequency and wavenumber is unstable to Tollmien-Schlichting waves, as in the case of the Blasius boundary layer flow past a flat plate. With increase in time, the unstable waves only undergo growth for a finite time interval, and this growth rate is itself a function of time. The influence of finite amplitude effects is studied by solving the full Navier-Stokes equations. It is found that the stability characteristics are markedly changed both by the consideration of the time evolution of the flow, and by the introduction of finite amplitude effects.
Author | : G.E.A. Meier |
Publisher | : Springer |
Total Pages | : 327 |
Release | : 2014-05-04 |
Genre | : Technology & Engineering |
ISBN | : 3709126886 |
This volume contributes to one of the most important topics of Fluid Mechanics in future and presents recent research results on control theory and applied control methods. Understanding and handling of control methods of nonlinear systems, typical of Fluid Mechanics, is the key to reduce losses and to improve the efficiency and safety of technical processes.
Author | : Demetri P. Telionis |
Publisher | : Springer |
Total Pages | : 440 |
Release | : 1981 |
Genre | : Science |
ISBN | : |
Author | : |
Publisher | : |
Total Pages | : 646 |
Release | : 1986 |
Genre | : Viscous flow |
ISBN | : |
Author | : National Aeronautics and Space Adm Nasa |
Publisher | : Independently Published |
Total Pages | : 38 |
Release | : 2018-10-21 |
Genre | : |
ISBN | : 9781729036778 |
The nonlinear evolution of long wavelength non-stationary cross-flow vortices in a compressible boundary layer is investigated and the work extends that of Gajjar (1994) to flows involving multiple critical layers. The basic flow profile considered in this paper is that appropriate for a fully three-dimensional boundary layer with O(1) Mach number and with wall heating or cooling. The governing equations for the evolution of the cross-flow vortex are obtained and some special cases are discussed. One special case includes linear theory where exact analytic expressions for the growth rate of the vortices are obtained. Another special case is a generalization of the Bassom & Gajjar (1988) results for neutral waves to compressible flows. The viscous correction to the growth rate is derived and it is shown how the unsteady nonlinear critical layer structure merges with that for a Haberman type of viscous critical layer. Gajjar, J. S. B. Unspecified Center NCC3-370; RTOP 505-90-5K