In agro-urban environments, the water resource conveyed by rural channels is susceptible to a gradual impoverishment due to the continuous combined sewer overflow release, constituting a pending and urgent issue for water management companies and the entire community. Reliable one-dimensional longitudinal dispersion coefficients D are required to model and study the hydrodynamics and water quality

A theoretical framework, based on the phenomenological theory of turbulence applied to scour-related processes due to plunging jets on cohesionless beds, is considered in this paper. More specifically, its predictive capability is assessed herein for large-scale domains, after it was developed for small scales elsewhere. The analysis focuses on both the time-evolution process and the equilibrium configuration

A pressure-driven two-layer channel flow of a Newtonian fluid with constant viscosity (top layer) and a fluid with a time-dependent viscosity (bottom layer) is numerically investigated. The bottom layer goes through an ageing process in which its viscosity increases due to the formation of internal structure, which is represented by a Coussot-type relationship. The resultant flow dynamics is the consequence

Abstract The ramifications of gust-front on atmospheric surface layer turbulence is a vexing issue, with nearly no information available over the Indian region where such events are not uncommon. Over the Indian peninsula, our recent field-experimental study has shown that a cold pool associated with the gust-front creates two distinct regimes in ASL turbulence, where temperature fluctuations display

Quantification of the terms in the transport equations of turbulence kinetic energy k and heat in the real urban roughness sublayer is inherently difficult due to variation of terms with thermal stability, wind speed, wind direction, and horizontal heterogeneity of most urban sites concerning morphometric parameters and land use. There is also a paucity of observations in the real urban environment

The fate and transport of sediment plumes in the ocean, such as those resulting from the disposal of deep-sea mining residuals, are affected by ambient crossflow. We present laboratory measurements of the depth at which a particle plume is trapped by ambient stratification for various crossflow and particle settling velocities. Results suggest that the trap depth declines exponentially with crossflow

Categorizing the types of roughness in environmental flows is important to establish the scaling laws for the roughness and bottom friction parameterization. The dependence of roughness height on roughness element geometry is discussed to clarify the difference between the two distinct d-type and k-type roughness under oscillatory flows. Direct numerical simulations (DNS) of oscillatory flow over transverse

When the Froude number F of a free-surface flow ranges between 0.3 and 3, the flow is unstable and frequently characterised by free surface undulations, with the undular hydraulic jump being a seminal flow in hydro-environmental mechanics. The presence of the free surface undulations significantly affects the flow field, with major velocity and pressure field redistributions between successive crests

A process of the removal of dissolved elements in the ocean by adsorption onto settling particulate matters (scavenging) is studied analytically and using the Lagrangian and Eulerian numerical methods. The generalized model of scavenging in a multicomponent reactive medium with first-order kinetics consisting of water and multifraction suspended particulate matter was developed. Two novel numerical

In this study, near-neutrally stratified planetary boundary layer (PBL) flows over complex terrain are numerically investigated via a one-way coupling of mesoscale numerical weather prediction (NWP) with unsteady computational fluid dynamics (CFD) codes. First, empirical turbulence model constants are modified to accomplish consistent turbulent viscosities between PBL schemes of mesoscale NWP and the

Transport of driftwood during heavy rainfall events can intensify the flood hazard. Driftwood accumulates at a bridge and backwater rises. Accumulated logs sink against the buoyancy force and the whole depth region is blocked. However, the mechanism governing the sink motion of accumulated logs at bridges is not fully understood. In this paper, we conducted the driftwood accumulation experiment at

Abstract The growing concern of the effects of potential releases of chemical, biological or radiological materials in populated areas has led to an increase in urban dispersion modelling over the past several decades. More recently, there has been a surge of research in the area of source term estimation (STE), in which inverse computational methods are used to predict a source (release) location

Abstract In coastal water systems, horizontal chaotic dispersion plays a significant role in the distribution and fate of pollutants. Lagrangian Coherent Structures (LCSs) provide useful tools to study the problem of the transport of pollutants and have only recently been applied to coastal waters. While the fundamentals of the LCS approach using idealised analytical flow fields are well established

Abstract Over the last two decades, the role of vegetation in the environmental and ecological restoration of surface water bodies has received much attention. In this context, the momentum exchange between the flow through the main channel and the riparian zone is a key mechanism. The primary goal of this study is to investigate the role of bank vegetation density on flow dynamics across the whole

Visible plumes above wet cooling towers are of great concern due to the associated aesthetic and environmental impacts. The parallel path wet/dry cooling tower is one of the most commonly used approaches for plume abatement, however, the associated capital cost is usually high due to the addition of the dry coils. Recently, passive technologies, which make use of free solar energy or the latent heat

Abstract A wind tunnel experiment was carried out to characterize the flow surrounding rectangular prisms of varying permeability, each set mounted on a stationary plane-bed surface and subsequently on an erodible bed. Laser-Doppler anemometer measurements of the horizontal and vertical velocity components were obtained in a grid that included an area adjacent to the windward face, enveloped the free

For many environmental projects and plans, it is necessary to model pollutant transport in rivers. Pollutant transport modeling is a complex phenomenon with multiple factors affecting it. The basic governing equation describing pollutant transport is advection–dispersion equation. There are two main parameters in this equation, namely, dispersion coefficient and flow velocity. In non-uniform flow regimes

Passive ventilation of buildings at night forms an essential part of a low-energy cooling strategy, enabling excess heat that has accumulated during the day to self-purge and be replaced with cooler night air. Instrumental to the success of a purge are the locations and areas of ventilation openings, and openings positioned at low and at high levels are a common choice as there is then the expectation

Partially filled pipes have many applications in hydraulic and environmental engineering; such as sewer and storm water collection pipes and circular culverts. Hydraulic jump can lead to scouring at hydraulic structures and thus excess energy should be dissipated to prevent scour and erosion. Calculation of conjugate depths in circular pipes and culverts is important in hydraulic engineering. The conjugate

We consider an inertial (large Reynolds number) gravity current (GC) released from a lock of length \(x_0\) and height \(h_0\) into an ambient fluid of height \(Hh_0\) which propagates along a channel with permeable floor and/or walls. The cross section (CS) of the container is defined by the general \(-f_1 (z) \le y \le f_2 (z)\) for \(0 \le z \le Hh_0\), while the top and the bottom are at \(z =

Abstract A 3D dry deposition scheme for particulate matter (PM) is presented as a Free-Libre and Open-Source Software (FOSS) library, DePaSITIA (RSE SpA). This combines some advanced formulations for the deposition mechanisms of sedimentation, inertial impaction, turbulent impaction and interception. The scheme also considers bouncing effects. The input quantities relate to the canopy elements (Leaf

Experiments were conducted in a straight channel that widens from a single channel to a compound channel based on a real navigation channel with a similar shape in a mountainous region of China. Flow entered the single channel and then the compound channel with vegetated floodplains. The channel widened at the interface between the single and compound channels, resulting in different flow depths between

Abstract The aim of the present study is to numerically investigate the scouring phenomenon downstream of a stilling basin for a wide range of Froude number and size of bed material. The numerical model was first verified. The results obtained from the numerical model concerning the maximum depth and profiles of the scoured hole were in agreement with the long-term experimental data. Thereupon, the

This paper presents new laboratory-scale numerical simulations of density-driven exchange flows generated across an idealised, submerged sill obstruction under both non-rotating and rotating frames of reference using the Bergen Ocean Model (BOM), a three-dimensional general ocean circulation model. Initial non-rotating BOM simulations are compared directly with previous laboratory data obtained in

This numerical study investigates the evolution of constant-flux high density fluid introduced vertically to a rotational low-density ambient through a circular inlet situated on top of a cone, which is mounted to the bottom of the simulation domain. The progress of the high density fluid over the bottom-mounted cone with steep side-wall slope of 39° is numerically modeled using large eddy simulations

Species specific hydrodynamic characterization is essential for assessing the suitability of various types of mangroves in coastal protection as the dissipation of wave energy within the mangroves is governed primarily by various aspects which are specific to the species to which they belong. In the present study a specific mangrove species was selected and its wave attenuation characteristics were

In order to address the problem of limited water renewal in restricted lagoons of moderate size having at least two tidal inlets, a method is proposed to enhance water exchange between the lagoon and the open sea. The method consists of altering either the amplitude or the phase of the tide in one of the inlets. It is shown in the paper that this will result in an alteration of the function of the

Vegetation in watercourses can influence different aspects of flow structure, subsequently affecting many processes of flow, such as pollutant transportation, sediment deposition and hydrophyte habitat distribution. Vegetation often occurs on one side of a channel, which requires understanding the effects of partial vegetation on the flow. Although many studies have been done on flows through uniform

Turbulent mixing processes in deep alpine Lake Garda (I) have not extensively been observed. Knowledge about drivers of turbulent fluxes are important for insights in the transport of matter, nutrients and pollutants, in the lake and in natural water bodies in general. In this paper, the occurrence of internal wave induced turbulent convection, termed 'internally forced convection', is addressed as

In this article we describe the details of an ABLE-LBM (Atmospheric Boundary Layer Environment-Lattice Boltzmann Model) validation study for urban building array turbulent flow simulations. The ABLE-LBM large-eddy simulation results were compared with a set of 3D magnetic resonance image (MRI) velocimetry data. The ABLE-LBM simulations used the same building layout and Reynolds numbers operated in

The quantification of turbulent mixing in nature is predicated by inherent randomness of causal events, and obtaining relevant turbulence statistics requires ensemble averaging of identical realizations that are unachievable in field observations or onerous in laboratory situations. Laboratory modeling is often used to study nonstationary natural processes, but jitters due to intrinsic variability

Air curtains are produced by thin vertical planar air jets and are used to prevent exchange flows between two fluids with a horizontal density gradient. They have been shown to work effectively provided the deflection modulus (DM) is greater than a critical value (DM = 0.14). Herein, results are presented from an experimental and modeling study of the initial transient development of the buoyancy distribution

The simultaneous observations from a Doppler weather radar and an instrumented micrometeorological tower, offer an opportunity to dissect the effects of a gust front on the surface layer turbulence in a tropical convective boundary layer. We present a case study where a sudden drop in temperature was noted at heights within the surface layer during the passage of a gust front in the afternoon time

An internal wave is a propagating disturbance within a stable density-stratified fluid. The internal seiche amplitude is often estimated through theories that describe the amplitude growth based on the Bulk Richardson number (Ri). However, most theoretical formulations neglect secondary effects that may influence the evolution of internal seiches. Since these waves have been pointed out as the most

In this laboratory study, propagation behaviour, particle deposition patterns, and suspension characteristics of non-cohesive particle-driven gravity currents formed under constant-volume release conditions were investigated. The experimental gravity currents were created in a two-dimensional lock exchange type tank using two different particles (silicon carbide and glass beads) with four different

Understanding scalar transport in solvents is important in chemical engineering, pollution control, and water remediation, where the longitudinal dispersion coefficient (LDC) is a key parameter for describing solute transport in fluids. For flow in classic conditions such as in a pipe or a regular open channel, formulas for LDC are derived from adopting the ideas of the advection–diffusion equation

The effects of obstacle-height variability on spatial characteristics of turbulent organized structures were investigated with the use of a large-eddy simulation technique for airflows over roughness obstacles. Two-types simulation cases were considered: one is uniform-height case in which uniform-height obstacles are aligned in streamwise direction, the other is height-variability case with staggered

Local pier scour has been recognized as one of the most significant causes of bridge failures. Despite numerous studies on the subject of local pier scour have been conducted, there remain problems in accurate scour prediction because almost of the past studies have focused only on scour depth around simple shape of a bridge pier with or without considering their time development, even though prototype

The following article addresses the issue of wind conditions around urban building development at pedestrian level. Factors that depend on those issues include wind comfort and air quality within urbanized spaces. The conditions specific of cities located in a temperate climate zone have been taken into account. The article is intended to identify aerodynamic phenomena characteristic of the three basic

In this study, we explore several integral and outer length scales of turbulence which can be formulated by using the dissipation of temperature fluctuations (\(\chi\)) and other relevant variables. Our analyses directly lead to simple yet non-trivial parameterizations for both spatially-averaged \(\overline{\chi }\) and the structure parameter of temperature (\(C_T^2\)). For our purposes, we make

Employing inclined negatively buoyant jets is one of the most advantageous means to discharge brine or waste in coastal environments. However, numerical prediction of mixing parameters for this kind of flow is still a challenge. In this investigation, CFD simulations of \(45^\circ \) inclined dense jets were conducted using realizable k–\(\epsilon \) model with buoyancy corrections and different values

An alluvial-proluvial fan (APF) has heterogeneous characteristics, which result in the development of imbricated gravel channel networks formed by flow erosion. In this type of aquifer, groundwater flow and solute transport are significantly affected by the connectivity of the channels. This paper investigates the 2D connectivity of a heterogeneous APF aquifer based on a case study of the Dali APF

Oil dispersion under a deep-water plunging breaker of height 0.15 m was studied by coupling the Lagrangian particle tracking code (NEMO3D) with the population balance model (VDROP). The wave hydrodynamics obtained in Part I (Cui et al. in Environ Fluid Mech 2020 (in press)) was used as input. It was observed that droplet inertia and major forces on droplets significantly impacted the transport of oil

Gravity currents propagating on \(12^\circ \), \(9^\circ \), \(6^\circ \), \(3^\circ \) unbounded uniform slopes and on an unbounded horizontal boundary are reported. Results show that there are two stages of the deceleration phase. In the early stage of the deceleration phase, the front location history follows \({(x_f+x_0)}^2 = {(K_I B)}^{1/2} (t+t_{I})\), where \((x_f+x_0)\) is the front location

Patches of vegetation in natural water bodies grow close to each other and may affect each other’s wake pattern with significant implications on nutrient uptake and local sediment transport. This experimental study analyzed the wakes of two neighboring circular patches of emergent artificial vegetation with different densities, with the tested solid volume fractions being equal to 0.059, 0.114, and

Bed-load transport is a complex process exhibiting anomalous dynamics, which cannot be efficiently described using the traditional advection–diffusion equation. This study aims at developing and testing a Hausdorff fractal derivative model to characterize scale-dependent, anomalous dynamics of bed-load transport through a heterogeneous gravel-bed. Applications show that the Hausdorff fractal derivative

A large set of experimental solute tracer breakthrough data (corresponding to more than 350 individual tracer breakthrough curves) in eight granular filter materials, were used to investigate the links between solute dispersivity and the shape of the pore velocity—relative pore area distributions for the materials. Solute dispersivity values and the shape of the pore velocity—relative pore area distributions

A series of experiments were conducted to quantify the dynamics of a filling box driven by a line plume that spans the full width of the enclosure. Three configurations were tested namely symmetric (centrally located plume), wall-bounded (plume attached to an end wall), and asymmetric. The front movement for the symmetric and wall-bounded configurations was well described by the standard filling box

The dispersion (transport and breakup) of oil droplets under breaking waves is essential for evaluating the impact of oil spills on the environment, and for designing countermeasures. In this part of the work (Part I), the hydrodynamics of a wave breaker in a 1.0 m deep tank obtained experimentally by Rapp and Melville (Philos Trans R Soc Lond A Math Phys Eng Sci 331(1622):735–800, 1990) using the

This paper aims at addressing issues related to the misrepresentation of the turbulent stratified flow for sand wave simulation using the continuum coupled flow and morphodynamics modeling approach. continuum flow and morphodynamics frameworks often consider the contributions of (i) suspended sediment-load in the sediment mass-balance equation and (ii) stratification in the equations of fluid motion

The water waves resulting from the collapse of a dam are important unsteady free surface flows in civil and environmental engineering. Considering the basic case of ideal dam break waves in a horizontal and rectangular channel the wave patterns observed experimentally depends on the initial depths downstream (hd) and upstream (ho) of the dam. For r = hd/ho above the transition domain 0.4–0.55, the

We report upon a series of laboratory experiments and complementary (two-dimensional) direct numerical simulations that explore the lock release of a fixed volume of dense fluid into a two-layer density-stratified ambient. By initial condition, the lock release experiments/simulations fall into one of two categories: full-depth and partial-depth. Our particular focus is on the “tailwaters” limiting

The complex three-dimensional flow that develops around an inclined flat solar panel near the ground is investigated using Computational Fluid Dynamics. The early stage evolution of the flow and the interaction of the shear layers emanating from the sides of the panel, the large separation region behind the panel and the boundary layers on the panel and ground are captured using Delayed Detached-Eddy

The influence of channel side slope on flow in strongly curved channel bends is studied numerically. The performances of five different turbulence models are investigated. Comparison to experimental measurements demonstrates that the fully 3D numerical model can reliably simulate a channel bend flow field. Among the tested turbulence models, the realizable k − ε model performed best. The present study

This paper proposes a model for predicting the longitudinal profiles of streamwise velocities in an open channel with a model patch of vegetation. The governing equation was derived from the momentum equation and flow continuity equation. The model can estimate the longitudinal profiles of velocities both inside and outside a vegetation patch. Laboratory experiments indicate that the longitudinal profiles

In this work, a summary of Leonardo da Vinci’s contribution in the field of fluid mechanics is reported. Some theoretical laws or fluid flows analyzed or drawn by Leonardo are highlighted, such as vortices, flow fields with obstacles, the continuity law, waves, velocity profiles in open channels, as well as some ingenious contributions in the field of hydraulic constructions and machines.

The results of an experimental study on the turbulence characteristics in flow over and downstream of an isolated bedform are presented. The vertical profiles of time-averaged streamwise velocity, Reynolds stresses and turbulent kinetic energy (TKE) fluxes at different horizontal locations over and downstream of a bedform are shown to demonstrate their variations. The experimental results signify a

Transport of air pollutants emitted from urban valleys can be strongly restricted by interactions between static and dynamic factors including topographic forcing, low-level atmospheric stability related to temperature inversions, and urban heat island-induced circulations. Interplay between these processes has a complex and dynamic nature, and is determinant for the evolution of different ventilation

In plunging jets and at hydraulic jumps, large amounts of air bubbles are entrained at the impingement of the liquid jet into the receiving body. Air is entrapped and advected into a turbulent shear layer with strong interactions between the air bubble advection process and momentum shear flow. In this new physical study, air–water flow measurements were systematically repeated with identical inflow

A compression wave is an unsteady rapidly-varied open channel flow motion, characterised by an increase in water depth. A detailed investigation was conducted in a prismatic asymmetrical channel, to better understand the physical processes observed in tidal/tsunami-bore affected estuaries with irregular topography. The prismatic channel was equipped with a 1 V:5H transverse slope across the full channel