Showing papers on "Turbulence published in 2017"
TL;DR: In this article, the authors describe wall-bounded turbulence as a deterministic high-dimensional dynamical system of interacting coherent structures, defined as eddies with enough internal dynamics to behave relatively autonomously from any remaining incoherent part of the flow.
Abstract: This article discusses the description of wall-bounded turbulence as a deterministic high-dimensional dynamical system of interacting coherent structures, defined as eddies with enough internal dynamics to behave relatively autonomously from any remaining incoherent part of the flow. The guiding principle is that randomness is not a property, but a methodological choice of what to ignore in the flow, and that a complete understanding of turbulence, including the possibility of control, requires that it be kept to a minimum. After briefly reviewing the underlying low-order statistics of flows at moderate Reynolds numbers, the article examines what two-point statistics imply for the decomposition of the flow into individual eddies. Intense eddies are examined next, including their temporal evolution, and shown to satisfy many of the properties required for coherence. In particular, it is shown that coherent structures larger than the Corrsin scale are a natural consequence of the shear. In wall-bounded turbulence, they can be classified into coherent dispersive waves and transient bursts. The former are found in the viscous layer near the wall and as very-large structures spanning the boundary layer thickness. Although they are shear-driven, these waves have enough internal structure to maintain a uniform advection velocity. Conversely, bursts exist at all scales, are characteristic of the logarithmic layer, and interact almost linearly with the shear. While the waves require a wall to determine their length scale, the bursts are essentially independent from it. The article concludes with a brief review of our present theoretical understanding of turbulent structures, and with a list of open problems and future perspectives.
268 citations
TL;DR: Anisotropic particles are common in many industrial and natural turbulent flows as discussed by the authors, and when these particles are small and neutrally buoyant, they follow Lagrangian trajectories while exhibiting rich orientational dynamics from the coupling of their rotation to the velocity gradients of the turbulence field.
Abstract: Anisotropic particles are common in many industrial and natural turbulent flows. When these particles are small and neutrally buoyant, they follow Lagrangian trajectories while exhibiting rich orientational dynamics from the coupling of their rotation to the velocity gradients of the turbulence field. This system has proven to be a fascinating application of the fundamental properties of velocity gradients in turbulence. When particles are not neutrally buoyant, they experience preferential concentration and very different preferential alignment than neutrally buoyant tracer particles. A vast proportion of the parameter range of anisotropic particles in turbulence is still unexplored, with most existing research focusing on the simple foundational cases of axisymmetric ellipsoids at low concentrations in homogeneous isotropic turbulence and in turbulent channel flow. Numerical simulations and experiments have recently developed a fairly comprehensive picture of alignment and rotation in these cases, and t...
257 citations
242 citations
TL;DR: In this article, the authors validate 3D steady Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) of cross-ventilation in a generic isolated enclosure with wind-tunnel measurements.
227 citations
04 May 2017
TL;DR: It is shown that ANN can establish a model similar to the gradient model, which is comparable to or larger than similarity models, but smaller than a two-parameter dynamic mixed model.
Abstract: An artificial neural network establishes a turbulence model for large-eddy simulation using direct numerical simulation of a turbulent channel flow. The resulting model is similar to an existing turbulence model (the gradient model).
212 citations
TL;DR: A review of major progress in inflow turbulence generation methods with an emphasis on fundamental ideas, key milestones, and representati... as mentioned in this paper, is presented in this paper, which is based on the weak recycling method, rooted in scaling arguments on the canonical incompressible boundary layer.
Abstract: Research activities on inflow turbulence generation methods have been vigorous over the past quarter century, accompanying advances in eddy-resolving computations of spatially developing turbulent flows with direct numerical simulation, large-eddy simulation (LES), and hybrid Reynolds-averaged Navier-Stokes–LES. The weak recycling method, rooted in scaling arguments on the canonical incompressible boundary layer, has been applied to supersonic boundary layer, rough surface boundary layer, and microscale urban canopy LES coupled with mesoscale numerical weather forecasting. Synthetic methods, originating from analytical approximation to homogeneous isotropic turbulence, have branched out into several robust methods, including the synthetic random Fourier method, synthetic digital filtering method, synthetic coherent eddy method, and synthetic volume forcing method. This article reviews major progress in inflow turbulence generation methods with an emphasis on fundamental ideas, key milestones, representati...
201 citations
TL;DR: In this article, known structures and self-sustaining mechanisms of wall turbulence are reviewed and explored in the context of the scale interactions implied by the nonlinear advective term in the Navier-Stokes equations.
Abstract: Known structures and self-sustaining mechanisms of wall turbulence are reviewed and explored in the context of the scale interactions implied by the nonlinear advective term in the Navier–Stokes equations. The viewpoint is shaped by the systems approach provided by the resolvent framework for wall turbulence proposed by McKeon & Sharma (J. Fluid Mech., vol. 658, 2010, pp. 336–382), in which the nonlinearity is interpreted as providing the forcing to the linear Navier–Stokes operator (the resolvent). Elements of the structure of wall turbulence that can be uncovered as the treatment of the nonlinearity ranges from data-informed approximation to analysis of exact solutions of the Navier–Stokes equations (so-called exact coherent states) are discussed. The article concludes with an outline of the feasibility of extending this kind of approach to high-Reynolds-number wall turbulence in canonical flows and beyond.
176 citations
TL;DR: A review of numerical simulations of rigid particles suspended in a flow can be found in this article, where the focus is on non-Brownian systems for which thermal fluctuations do not play a role, whereas interparticle forces may result in particle self-assembly.
Abstract: Numerical simulations are extensively used to investigate the motion of suspended particles in a fluid and their influence on the dynamics of the overall flow. Contexts range from the rheology of concentrated suspensions in a viscous fluid to the dynamics of particle-laden turbulent flows. This review summarizes several current approaches to the numerical simulation of rigid particles suspended in a flow, pointing out both common features and differences, along with their primary range of application. The focus is on non-Brownian systems for which thermal fluctuations do not play a role, whereas interparticle forces may result in particle self-assembly. Applications may include the motion of a few isolated particles with complex shape or the collective dynamics of many suspended particles.
168 citations
TL;DR: In this paper, the influence of T-semi attached rib on the turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel was explored.
Abstract: This study aimed at exploring influence of T-semi attached rib on the turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel. For this purpose, convection heat transfer of the silver-water nanofluid in a ribbed microchannel was numerically studied under a constant heat flux on upper and lower walls as well as isolated side walls. Calculations were done for a range of Reynolds numbers between 10,000 and 16,000, and in four different sorts of serrations with proportion of rib width to hole of serration width (R/W). The results of this research are presented as the coefficient of friction, Nusselt number, heat transfer coefficient and thermal efficiency, four different R/W microchannels. The results of numerical modeling showed that the fluid's convection heat transfer coefficient is increased as the Reynolds number and volume fraction of solid nanoparticle are increased. For R/W=0.5, it was also maximum for all the volume fractions of nanoparticle and different Reynolds numbers in comparison to other similar R/W situations. That's while friction coefficient, pressure drop and pumping power is maximum for serration with R/W=0 compared to other serration ratios which lead to decreased fluid-heat transfer performance.
167 citations
TL;DR: This work shows how the motion of active matter along a micro-channel transitions to meso-scale turbulence through the evolution of locally disordered patches (active puffs) from an ordered vortex-lattice flow state, and demonstrates that the stationary critical exponents of this transition in a channel coincide with the directed percolation universality class.
Abstract: Meso-scale turbulence is an innate phenomenon, distinct from inertial turbulence, that spontaneously occurs at low Reynolds number in fluidized biological systems. This spatiotemporal disordered flow radically changes nutrient and molecular transport in living fluids and can strongly affect the collective behaviour in prominent biological processes, including biofilm formation, morphogenesis and cancer invasion. Despite its crucial role in such physiological processes, understanding meso-scale turbulence and any relation to classical inertial turbulence remains obscure. Here we show how the motion of active matter along a micro-channel transitions to meso-scale turbulence through the evolution of locally disordered patches (active puffs) from an ordered vortex-lattice flow state. We demonstrate that the stationary critical exponents of this transition to meso-scale turbulence in a channel coincide with the directed percolation universality class. This finding bridges our understanding of the onset of low-Reynolds-number meso-scale turbulence and traditional scale-invariant turbulence in confinement.
154 citations
Book•
01 Nov 2017TL;DR: In this article, the authors present a review of single-phase flow concepts and their application in the context of two-phase flows. But their focus is on the application of these concepts in computer simulation and virtual prototyping.
Abstract: 1. Review of Single-Phase Flow 1.1 Basic Fluid Flow Concepts 1.2 Flow Field Descriptions 1.3 Conservation Laws 1.4 Turbulence 1.5 Solution Techniques 1.6 Homework Problem Assignments 2. Basic Concepts of Two-Phase Flow Theory 2.1 Flow Regime Classifications and Modeling Approaches 2.2 Dispersed Flow Definitions, Phase Properties and Phase Coupling 2.3 Mass, Momentum and Heat Transfer 2.4 Statistical Descriptions 2.5 Highlights of Industrial Dispersed Flows 2.6 Homework Problem Assignments 3. Derivations of Two-Phase Flow Modelling Equations 3.1 Averaging Techniques and Constitutive Equations 3.2 Mixture Models 3.3 Separated Flow Models 3.4 Problem Assignments 4. Analyses and Solutions of Basic Two-Phase Flow Problems 4.1 Numerical Solution Tools 4.2 Mixture Flow Applications 4.3 Particle Trajectory Dynamics 4.4 Two-Fluid Model Applications 4.5 Project Assignments 5. Selected Case Studies 5.1 Mathematical Modeling, Computer Simulation and Virtual Prototyping 5.2 Quasi-Homogeneous Equilibrium Flows (EULER) 5.3 Separated Flows 1: Fluid Particle Models (EULER_Lagrange) 5.4 Separated Flows 2: Two-Fluid Models (EULER-EULER) Appendicies
TL;DR: In this paper, the transition between roll-and cellular-type convection was investigated systematically for the first time using large-eddy simulations (LES) spanning a range of values between zero (neutral) and 1041 (highly convective), where N is the CBL depth and L is the Obukhov length.
Abstract: Both observational and numerical studies of the convective boundary layer (CBL) have demonstrated that when surface heat fluxes are small and mean wind shear is strong, convective updrafts tend to organize into horizontal rolls aligned within 10–20
$$^\circ $$
of the geostrophic wind direction. However, under large surface heat fluxes and weak to negligible shear, convection tends to organize into open cells, similar to turbulent Rayleigh-Benard convection. Using a suite of 14 large-eddy simulations (LES) spanning a range of $$-z_i/L$$
between zero (neutral) and 1041 (highly convective), where $$z_i$$
is the CBL depth and L is the Obukhov length, the transition between roll- and cellular-type convection is investigated systematically for the first time using LES. Mean vertical profiles including velocity variances and turbulent transport efficiencies, as well the “roll factor,” which characterizes the rotational symmetry of the vertical velocity field, indicate the transition occurs gradually over a range of $$-z_i/L$$
; however, the most significant changes in vertical profiles and CBL organization occur from near-neutral conditions up to about $$-z_i/L \approx $$
15–20. Turbulent transport efficiencies and quadrant analysis are used to characterize the turbulent transport of momentum and heat with increasing $$-z_i/L$$
. It is found that turbulence transports heat efficiently from weakly to highly convective conditions; however, turbulent momentum transport becomes increasingly inefficient as $$-z_i/L$$
increases.
TL;DR: In this paper, a 3D Lagrangian Coherent Structures (LCS) was used to analyze the dynamics of cavitation-vortex interactions in the Delft twisted hydrofoil.
TL;DR: Estimates of spectral resolution power for under-resolved turbulent Euler flows obtained with high-order discontinuous Galerkin (DG) methods are presented and are regarded as useful guidelines for no-model DG-based simulations of free turbulence at very high Reynolds numbers.
TL;DR: In this paper, the authors review the space-time correlation models in both the Eulerian and Lagrangian frames of reference, which include the random sweeping and local straining models for isotropic and homogeneous turbulence, Taylor's frozen-flow model and the elliptic approximation model for turbulent shear flows, and the linear wave propagation model and swept-wave model for compressible turbulence.
Abstract: Space-time correlation is a staple method for investigating the dynamic coupling of spatial and temporal scales of motion in turbulent flows. In this article, we review the space-time correlation models in both the Eulerian and Lagrangian frames of reference, which include the random sweeping and local straining models for isotropic and homogeneous turbulence, Taylor's frozen-flow model and the elliptic approximation model for turbulent shear flows, and the linear-wave propagation model and swept-wave model for compressible turbulence. We then focus on how space-time correlations are used to develop time-accurate turbulence models for the large-eddy simulation of turbulence-generated noise and particle-laden turbulence. We briefly discuss their applications to two-point closures for Kolmogorov's universal scaling of energy spectra and to the reconstruction of space-time energy spectra from a subset of spatial and temporal signals in experimental measurements. Finally, we summarize the current understanding of space-time correlations and conclude with future issues for the field.
TL;DR: A review of the most relevant (and often contrasting) theoretical approaches to Rayleigh-Taylor turbulence together with numerical and experimental evidence for their support can be found in this paper, where the focus is mainly on the classical Boussinesq Rayleigh−Taylor turbulence of miscible fluids, but other fluid systems with viscoelastic behavior, affected by rotation of the reference frame, and, finally, in the presence of reactions.
Abstract: Basic fluid equations are the main ingredient in the development of theories of Rayleigh–Taylor buoyancy-induced instability. Turbulence arises in the late stage of the instability evolution as a result of the proliferation of active scales of motion. Fluctuations are maintained by the unceasing conversion of potential energy into kinetic energy. Although the dynamics of turbulent fluctuations is ruled by the same equations controlling the Rayleigh–Taylor instability, here only phenomenological theories are currently available. The present review provides an overview of the most relevant (and often contrasting) theoretical approaches to Rayleigh–Taylor turbulence together with numerical and experimental evidence for their support. Although the focus is mainly on the classical Boussinesq Rayleigh–Taylor turbulence of miscible fluids, the review extends to other fluid systems with viscoelastic behavior, affected by rotation of the reference frame, and, finally, in the presence of reactions.
TL;DR: In this article, the effect of attack angle of ribs and Al2O3 nanoparticles on the heat transfer enhancement was investigated and the results showed that the presence of ribs with the creation of eddy on the direction of flow causes better mixture of flow and consequently, heat transfer increases and adding nanoparticles to the base flow causes more augment of heat transfer.
TL;DR: In this paper, the heat transfer of laminar and turbulent flow of water/Al2O3 nanofluid in the volume fraction of φ = 0-4% of solid nanoparticles in Reynolds numbers of 500-25,000 have been numerically investigated.
Abstract: In present study, the heat transfer of laminar and turbulent flow of water/Al2O3 nanofluid in the volume fraction of φ = 0–4% of solid nanoparticles in Reynolds numbers of 500–25,000 have been numerically investigated. The studied geometrics is a three-dimensional tube with the diameter of D = 2 cm and the length of L = 50 cm. In order to increase the heat transfer inside horizontal tube, the twisted tape in different aspect ratios has been used. In this research, the considered geometrics with aspect parameters, such as the twisted ratios (P/W) of 3, 3.5 and 4, the space ratios (C/D) of 0.3, 0.4 and 0.5 and the tape width ratios (W/D) at the range of 0.5–0.9, has been investigated. The results indicate that, in the turbulent flow, the use of solid nanoparticle in higher volume fractions and Reynolds numbers, comparing to the laminar flow, improves heat transfer. The existence of solid nanoparticles in lower twisted ratios (P/W) has great effect on the heat transfer enhancement. In the laminar flow, by increasing the width of twisted tape and the concentration of nanoparticles, heat transfer enhances.
TL;DR: In this paper, the authors define a path in parameter space between classical models and asymptotic conditions from the requirements to enforce a MAC balance and to preserve the ratio between the magnetic diffusion and convective overturn times (the magnetic Reynolds number).
Abstract: Self-sustained convective dynamos in planetary systems operate in an asymptotic regime of rapid rotation, where a balance is thought to hold between the Coriolis, pressure, buoyancy and Lorentz forces (the MAC balance). Classical numerical solutions have previously been obtained in a regime of moderate rotation where viscous and inertial forces are still significant. We define a uni-dimensional path in parameter space between classical models and asymptotic conditions from the requirements to enforce a MAC balance and to preserve the ratio between the magnetic diffusion and convective overturn times (the magnetic Reynolds number). Direct numerical simulations performed along this path show that the spatial structure of the solution at scales larger than the magnetic dissipation length is largely invariant. This enables the definition of large-eddy simulations resting on the assumption that small-scale details of the hydrodynamic turbulence are irrelevant to the determination of the large-scale asymptotic state. These simulations are shown to be in good agreement with direct simulations in the range where both are feasible, and can be computed for control parameter values far beyond the current state of the art, such as an Ekman number . We obtain strong-field convective dynamos approaching the MAC balance and a Taylor state to an unprecedented degree of accuracy. The physical connection between classical models and asymptotic conditions is shown to be devoid of abrupt transitions, demonstrating the asymptotic relevance of classical numerical dynamo mechanisms. The fields of the system are confirmed to follow diffusivity-free, power-based scaling laws along the path.
TL;DR: In this article, the authors presented a numerical study of the turbulent compressible fluid in a supersonic ejector and compared seven RANS turbulence closures with different near-wall modeling options to investigate the wall treatment effect on numerical results.
TL;DR: In this paper, a perforated vortex generator (PVG) was developed to improve convection heat transfer in a circular tube in turbulent flow regime with the Reynolds number over the range 3000-21,000 using air as the working fluid under uniform wall heat flux boundary condition.
TL;DR: In this article, the authors compared single and two-phase modeling approaches for forced convection flow of water/TiO2 nanofluid in a horizontal tube with constant wall heat flux boundary condition where flow regime is turbulent.
Abstract: The main goal of this paper is to compare single- and two-phase modeling approaches for forced convection flow of water/TiO2 nanofluid. The considered geometry is a horizontal tube with constant wall heat flux boundary condition where flow regime is turbulent. A computational fluid dynamics (CFD) approach is utilized for heat transfer and flow field estimation of the single-phase and three different two-phase approaches, namely, volume of fluid, mixture, and Eulerian models. Results are presented for Reynolds numbers ranging from 9000 to 21,000, for different nanoparticle diameters ranging from 20 to 40 nm, and for values of volume fractions ranging from 0 to 4%. The obtained results show that the values of entropy generation for thermal and turbulent dissipation are very close for the single-phase and mixture models. Numerical investigation showed that the values of entropy production for pure water are identical regardless of the CFD approach; however, when the volume fraction of nanoparticles i...
TL;DR: In this paper, the low-frequency dynamics of a high Reynolds number impinging shock-wave/turbulent boundary-layer interaction with strong mean-flow separation were analyzed for grid-converged large-eddy simulations.
Abstract: We analyse the low-frequency dynamics of a high Reynolds number impinging shock-wave/turbulent boundary-layer interaction (SWBLI) with strong mean-flow separation. The flow configuration for our grid-converged large-eddy simulations (LES) reproduces recent experiments for the interaction of a Mach 3 turbulent boundary layer with an impinging shock that nominally deflects the incoming flow by. The Reynolds number based on the incoming boundary-layer thickness of is considerably higher than in previous LES studies. The very long integration time of allows for an accurate analysis of low-frequency unsteady effects. Experimental wall-pressure measurements are in good agreement with the LES data. Both datasets exhibit the distinct plateau within the separated-flow region of a strong SWBLI. The filtered three-dimensional flow field shows clear evidence of counter-rotating streamwise vortices originating in the proximity of the bubble apex. Contrary to previous numerical results on compression ramp configurations, these Gortler-like vortices are not fixed at a specific spanwise position, but rather undergo a slow motion coupled to the separation-bubble dynamics. Consistent with experimental data, power spectral densities (PSD) of wall-pressure probes exhibit a broadband and very energetic low-frequency component associated with the separation-shock unsteadiness. Sparsity-promoting dynamic mode decompositions (SPDMD) for both spanwise-averaged data and wall-plane snapshots yield a classical and well-known low-frequency breathing mode of the separation bubble, as well as a medium-frequency shedding mode responsible for reflected and reattachment shock corrugation. SPDMD of the two-dimensional skin-friction coefficient further identifies streamwise streaks at low frequencies that cause large-scale flapping of the reattachment line. The PSD and SPDMD results of our impinging SWBLI support the theory that an intrinsic mechanism of the interaction zone is responsible for the low-frequency unsteadiness, in which Gortler-like vortices might be seen as a continuous (coherent) forcing for strong SWBLI.
TL;DR: In this paper, the authors dealt with turbulent boundary layers under adverse pressure gradients and well-resolved large-eddy simulations were performed to assess the influence of the streamwise pressure develo...
Abstract: This study deals with turbulent boundary layers under adverse-pressure gradients. Well-resolved large-eddy simulations (LES) were performed to assess the influence of the streamwise pressure develo ...
TL;DR: In this article, the mixed turbulent convective heat transfer characteristics in dimpled tubes of parabolic trough receiver are numerically studied at a certain Reynolds number of 2.2×1010 to produce substantial surface heat transfer augmentations with relatively small pressure drop penalties.
TL;DR: In this paper, an isotherm heat transfer system has been designed and built in order to investigate the effect of utilizing water/graphene oxide nanofluid flow on heat transfer and the friction coefficient in a circular profile copper tube.
TL;DR: In this article, the fundamental flow physics of the interaction between an array of fuel jets and multi air jets in a supersonic transverse flow were investigated by using the Reynolds-averaged Navier-Stokes equations with Menter's Shear Stress Transport (SST) turbulence model.
TL;DR: In this article, the authors propose a mechanism whereby the intense, sheet-like structures naturally formed by dynamically aligning Alfv´enic turbulence are destroyed by magnetic reconnection at a scale ˆλ D, larger than the dissipation scale predicted by models of intermittent, dynamically aligned turbulence, which effectively imposes an upper limit on the anisotropy of the structures within the perpendicular plane.
Abstract: We propose a mechanism whereby the intense, sheet-like structures naturally formed by dynamically aligning Alfv´enic turbulence are destroyed by magnetic reconnection at a scale ˆλ D, larger than the dissipation scale predicted by models of intermittent, dynamically aligning turbulence. The reconnection process proceeds in several stages: first, a linear tearing mode with N magnetic islands grows and saturates, and then the X-points between these islands collapse into secondary current sheets, which then reconnect until the original structure is destroyed. This effectively imposes an upper limit on the anisotropy of the structures within the perpendicular plane, which means that at scale ˆλD the turbulent dynamics change: at scales larger than ˆλD, the turbulence exhibits scale-dependent dynamic alignment and a spectral indexapproximately equal to −3/2, while at scales smaller than ˆλD, the turbulent structures undergo a succession of disruptions due to reconnection, limiting dynamic alignment, steepening the effective spectral index and changing the final dissipation scale. The scaling of ˆλD with the Lundquist (magnetic Reynolds) number SL⊥ depends on the order of the statistics being considered, and on the specific model of intermittency; the transition between the two regimes in the energy spectrum is predicted at approximately ˆλD ∼ SL⊥^−0.6 . The spectral index below ˆλD is bounded between −5/3 and −2.3. The final dissipation scale is at ˆλη,∞ ∼ SL⊥^−3/4, the same as the Kolmogorov scale arising in theories of turbulence that do not involve scale-dependent dynamic alignment.
TL;DR: In this article, a detailed characterization of bed types, including grain size, grain-fabric and mineralogical analyses, was developed using a numerical suspension capacity model for radially spreading and decelerating turbidity currents.
Abstract: Sedimentary facies in the distal parts of deep-marine lobes can diverge significantly from those predicted by classical turbidite models, and sedimentological processes in these environments are poorly understood. This gap may be bridged using outcrop studies and theoretical models. In the Skoorsteenberg Formation (South Africa), a downstream transition from thickly bedded turbidite sandstones to argillaceous, internally layered hybrid beds, is observed. The hybrid beds have a characteristic stratigraphic and spatial distribution, being associated with bed successions which generally coarsen and thicken-upward reflecting deposition on the fringes of lobes in a dominantly progradational system. Using a detailed characterization of bed types, including grain size, grain-fabric and mineralogical analyses, a process-model for flow evolution is developed. This is explored using a numerical suspension capacity model for radially spreading and decelerating turbidity currents. The new model shows how decelerating sediment suspensions can reach a critical suspension capacity threshold beyond which grains are not supported by fluid turbulence. Sand and silt particles, settling together with flocculated clay, may form low yield strength cohesive flows; development of these higher concentration lower boundary layer flows inhibits transfer of turbulent kinetic energy into the upper parts of the flow ultimately resulting in catastrophic loss of turbulence and collapse of the upper part of the flow. Advection distances of the now transitional to laminar flow are relatively long (several kilometres) suggesting relatively slow dewatering (several hours) of the low yield strength flows. The catastrophic loss of turbulence accounts for the presence of such beds in other fine-grained systems without invoking external controls or large-scale flow partitioning and also explains the abrupt pinch-out of all divisions of these sandstones. Estimation of the point of flow transformation is a useful tool in the prediction of heterogeneity distribution in subsurface systems.