Journal ArticleDOI
Three-dimensional oscillatory flow over steep ripples
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In this article, the authors investigated the process which leads to the appearance of three-dimensional vortex structures in the oscillatory flow over two-dimensional ripples by means of direct numerical simulations of Navier-Stokes and continuity equations.Abstract:
The process which leads to the appearance of three-dimensional vortex structures in the oscillatory flow over two-dimensional ripples is investigated by means of direct numerical simulations of Navier–Stokes and continuity equations. The results by Hara & Mei (1990a), who considered ripples of small amplitude or weak fluid oscillations, are extended by considering ripples of larger amplitude and stronger flows respectively. Nonlinear effects, which were ignored in the analysis carried out by Hara & Mei (1990a), are found either to have a destabilizing effect or to delay the appearance of three-dimensional flow patterns, depending on the values of the parameters. An attempt to simulate the flow over actual ripples is made for moderate values of the Reynolds number. In this case the instability of the basic two-dimensional flow with respect to transverse perturbations makes the free shear layer generated by boundary layer separation become wavy as it leaves the ripple crest. Then the amplitude of the waviness increases and eventually complex three-dimensional vortex structures appear which are ejected in the irrotational region. Sometimes the formation of mushroom vortices is observed.read more
Citations
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A Ghost-Cell Immersed Boundary Method for Flow in Complex Geometry
Yu-Heng Tseng,Joel H. Ferziger +1 more
TL;DR: An efficient ghost-cell immersed boundary method (GCIBM) for simulating turbulent flows in complex geometries is presented in this paper, where a boundary condition is enforced through a ghost cell method.
Journal ArticleDOI
A ghost-cell immersed boundary method for flow in complex geometry
Yu-Heng Tseng,Joel H. Ferziger +1 more
TL;DR: An efficient ghost-cell immersed boundary method (GCIBM) for simulating turbulent flows in complex geometries is presented in this article, where a boundary condition is enforced through a ghost cell method.
Book
The Turbulent Ocean
TL;DR: The Turbulent Ocean as discussed by the authors describes the principal dynamic processes that control the distribution of turbulence, its dissipation of kinetic energy and its effects on the dispersion of properties such as heat, salinity, and dissolved or suspended matter in the deep ocean, the shallow coastal and the continental shelf seas.
Journal ArticleDOI
Mechanics of coastal forms
TL;DR: In this article, a review of the morphodynamics of the coastal region is presented, focusing on morphodynamic stability analyses that allow understanding of the behavior of morphological features that are repetitive in both space and time.
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Numerical simulation of sand waves in a turbulent open channel flow
TL;DR: In this paper, a coupled hydro-morphodynamic numerical model was developed for simulation of stratified, turbulent flow over a mobile sand bed. The model is based on the curvilinear immersed boundary approach of Khosronejad et al. and is applied to simulate sand wave initiation, growth and evolution in a mobile bed laboratory open channel.
References
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An Introduction to Fluid Dynamics. By G. K. Batchelor. Pp. 615. 75s. (Cambridge.)
TL;DR: In this paper, the Navier-Stokes equation is derived for an inviscid fluid, and a finite difference method is proposed to solve the Euler's equations for a fluid flow in 3D space.
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Numerical Calculation of Time‐Dependent Viscous Incompressible Flow of Fluid with Free Surface
Francis H. Harlow,J. Eddie Welch +1 more
TL;DR: In this paper, a new technique is described for the numerical investigation of the time-dependent flow of an incompressible fluid, the boundary of which is partially confined and partially free The full Navier-Stokes equations are written in finite-difference form, and the solution is accomplished by finite-time step advancement.
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Application of a Fractional-Step Method to Incompressible Navier-Stokes Equations
John Kim,Parviz Moin +1 more
TL;DR: In this paper, a numerical method for computing three-dimensional, time-dependent incompressible flows is presented based on a fractional-step, or time-splitting, scheme in conjunction with the approximate-factorization technique.
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Quantitative universality for a class of nonlinear transformations
TL;DR: In this article, a large class of recursion relations xn+l = Af(xn) exhibiting infinite bifurcation is shown to possess a rich quantitative structure essentially independent of the recursion function.
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Non-linear resonant instability in boundary layers
TL;DR: In this article, an analysis of resonant triads of Tollmien-Schlichting waves in an unstable boundary layer is made, and exact solutions of the general interaction equations are presented for a particular profile consisting of a layer of constant shear bounded by a uniform flow.