The article surveys the current state of our understanding turbidity currents, with an emphasis on their fluid mechanics. It highlights significant role these currents play within global sediment cycle, and importance in environmental processes formation hydrocarbon reservoirs. Events mechanisms governing initiation are reviewed, along experimental observations findings from field studies regarding internal velocity density structure. As propagate over seafloor, they can trigger evolution a...

Direct numerical simulations are performed of gravity-current fronts in the lock-exchange configuration. The case small density differences is considered, where Boussinesq approximations can be adopted. key objective investigation a detailed analysis flow structure at foremost part front, no previous high-resolution data were available. For simulations, high-order methods used, based on spectral and spectral-element discretizations compact finite differences. A three-dimensional simulation...

Vortex breakdown of nominally axisymmetric, swirling incompressible flows with jet- and wake-like axial velocity distributions issuing into a semi-infinite domain is studied by means direct numerical simulations. By selecting two-parametric profile for which the steady axisymmetric well-studied (Grabowski & Berger 1976), issues are addressed regarding role three-dimensionality unsteadiness respect to existence, mode selection, internal structure vortex breakdown, in terms two governing...

The steady thermocapillary motion in a square cavity with top free surface the absence of gravitational forces is considered. heated from side vertical boundaries isothermal while horizontal are adiabatic. relative change tension very small, i.e., an appropriate capillary number tends to zero, so that assumed remain flat at leading order. A finite-difference method employed compute flow field. Numerically accurate solutions obtained for range Prandtl numbers and Reynolds Re as high 5×104....

Results are presented from a high-resolution computational study of particle-driven gravity currents in plane channel. The investigation was conducted order to obtain better insight into the energy budget and mixing behaviour such flows. Two- three-dimensional simulations discussed, effects different factors influencing flow examined detail. Among these aspect ratio initial suspension reservoir, settling speed particles, level turbulence suspension. While most is concerned with lock-exchange...

The evolution of the two- and three-dimensional structures in a temporally growing plane shear layer is numerically simulated with discrete vortex dynamics method. We include two signs vorticity thus account for effect weaker boundary leaving splitter plate which used to create spatially developing mixing layer. interaction between layers changes symmetry properties seen single vorticity-layer calculation results closer agreement experimental observations interface streams. Our calculations...

The three-dimensional structure of a moderate-Reynolds-number (≈ 100) plane wake behind flat plate subjected to periodic spanwise perturbations has been studied both experimentally and numerically. Comparisons between experimental interface visualizations numerical calculations demonstrate that important features the development evolution can be reproduced by inviscid vortex dynamics. It is shown redistribution, reorientation stretching vorticity leads formation counter-rotating pairs...

Environmental fluid mechanics underlies a wealth of natural, industrial, and, by extension, societal challenges. As we strive toward more sustainable planet, there is wide range problems to be tackled, from fundamental advances in understanding and modeling stratified turbulence consequent mixing applied studies pollution transport the ocean, atmosphere, urban environments. The discussions outcomes recent Les Houches School Physics meeting are summarized here with intent providing resource...

Many waterbodies across the United States do not meet water quality standards. To help determine where and to what extent improvements should be sought, policymakers must consider costs of regulations with their monetized values. We ...Scientific knowledge related quantifying benefits for landscape-wide does current regulatory benefit–cost analysis needs in States. In this study we addressed gap by ...

Numerical simulations are presented which, in conjunction with the accompanying experimental investigation by Petitjeans & Maxworthy (1996), intended to elucidate miscible flow that is generated if a fluid of given viscosity and density displaces second different such properties capillary tube or plane channel. The global features flow, as fraction displaced left behind on walls, largely controlled dimensionless quantities form Péclet number Pe , an Atwood At gravity parameter. However,...

Density-driven instabilities between miscible fluids in a vertical Hele-Shaw cell are investigated by means of experimental measurements, as well two- and three-dimensional numerical simulations. The experiments focus on the early stages instability growth, they provide detailed information regarding growth rates most amplified wavenumbers function governing Rayleigh number Ra . They identify two clearly distinct parameter regimes: low- , ‘Hele-Shaw’ regime which dominant wavelength scales...

The spiral form of vortex breakdown observed in the numerical simulations Ruith et al. (J. Fluid Mech., vol. 486, 2003, p. 331) is interpreted as a nonlinear global mode originating at convective/absolute instability transition point lee bubble. local absolute frequency station shown to yield satisfactory prediction precession measured three-dimensional direct simulations.

A detailed two-part computational investigation is conducted into the dynamical evolution of two-dimensional miscible porous media flows in quarter five-spot arrangement injection and production wells. High-accuracy direct numerical simulations are performed that reproduce all dynamically relevant length scales solving vorticity–streamfunction formulation Darcy's law. The accuracy method demonstrated by a comparison simulation data with linear stability results for radial source flow. Within...

Rectilinear homogeneous miscible displacements with gravity override are analysed by means of direct numerical simulations on the basis vorticity–streamfunction formulation governing equations. The vorticity-based point view offers advantage clearly attributing dominant flow characteristics to effects viscosity contrast, density difference, impermeable boundary conditions, or interactions among above. Basic considerations regarding vorticity field show that in an integral sense coupling...

The gravitational settling of an initially random suspension small solid particles in homogeneous turbulence is investigated numerically. simulations are based on a pseudospectral method to solve the fluid equations combined with Lagrangian point-particle model for particulate phase (Eulerian-Lagrangian approach). focus enhancement mean particle velocity turbulent carrier fluid, as compared single quiescent fluid. Results presented both one-way coupling, when flow not affected by presence...

The constant initial speed of propagation ( V ) heavy gravity currents, density ρ C , released from behind a lock and along the bottom boundary tank containing linearly stratified fluid has been measured experimentally calculated numerically. difference, to top, stratification is (ρ b −ρ 0 its intrinsic frequency N . For given ratio depth h total H it found that dimensionless internal Froude number, Fr = / NH independent length logarithmic function parameter R )/(ρ ), except at small values...

The present investigation explores the unsteady dynamics of large density contrast non-Boussinesq lock-exchange flows by means high-resolution two-dimensional simulations incompressible variable-density Navier–Stokes equations, employing a combination spectral and compact finite-difference methods. For small contrasts, closely reproduce earlier Boussinesq results for corresponding flows. Across entire range good agreement is obtained between computed front propagation velocities experimental...

We study the inviscid mechanisms governing three-dimensional evolution of an axisymmetric jet by means vortex filament simulations. The spatially periodic calculations provide a detailed picture processes leading to concentration, reorientation, and stretching vorticity. In purely case, wavy perturbation in streamwise direction leads formation rings connected braid regions, which become depleted curvature shear layer loss symmetry as compared plane layer, position free stagnation point...

In this review article, we discuss recent progress with regard to modeling gravity-driven, high Reynolds number currents, the emphasis on depth-resolving, high-resolution simulations. The initial sections describe new developments in conceptual of such currents for purpose identifying Froude number–current height relationship, spirit pioneering work by von Kármán and Benjamin. A brief introduction depth-averaged approaches follows, including box models shallow water equations. Subsequently,...

Submarine fans, supplied primarily by turbidity currents, constitute the largest sediment accumulations on Earth. Generally accepted models of current behavior imply they should dissipate rapidly very small gradients submarine thus their persistence over long distances is enigmatic. We present numerical evidence, constrained published field data, suggesting that currents traveling low slopes and carrying fine particles have a stably stratified shear layer along upper interface, which...

Abstract When a layer of particle-laden fresh water is placed above clear, saline water, both double-diffusive and Rayleigh–Taylor instabilities may arise. The present investigation extends the linear stability analysis Burns & Meiburg ( J. Fluid Mech. , vol. 691, 2012, pp. 279–314) into nonlinear regime, by means two- three-dimensional direct numerical simulations (DNS). initial instability growth in DNS seen to be consistent with dominant modes predicted analysis. subsequent vigorous...

We develop a physical and computational model for performing fully coupled, grain-resolved direct numerical simulations of cohesive sediment, based on the immersed boundary method. The distributes forces over thin shell surrounding each particle, thereby allowing spatial temporal resolution during particle–particle interactions. influence is captured by single dimensionless parameter in form cohesion number, which represents ratio gravitational acting particle. test validate force binary...

We introduce a computational model for high‐resolution simulations of particle‐laden gravity currents. The features the are described in detail, and validation data discussed. Physical results presented that focus on influence particle entrainment from underlying bed. As turbulent motions detach particles bottom surface, resuspended entrained over entire length current transferred to current's head, causing it become denser potentially accelerating front current. conditions under which...