The goal of this paper is to discuss the spatial averaging concept in environmental hydraulics and develop it further by considering transport equations for fluid momentum, passive substances, suspended sediments. theorems, double-averaged (in time space) momentum equation, advection-diffusion a substance sediments are introduced their limitations applications modeling rough-bed flows, experimental design, data interpretation discussed. suggested differ from those considered terrestrial...

The paper briefly outlines the double-averaging methodology for studying environmental rough-bed flows. It focuses on applications of this in hydraulics by providing several examples illustrating advantages over conventional approaches. Examples include: (1) identification specific flow layers and types; (2) vertical distribution double-averaged velocity between roughness tops troughs; (3) momentum fluxes sinks typical types due to turbulence, mean heterogeneity, secondary currents, form...

The behavior of turbulent open channel flows over permeable surfaces is not well understood. In particular, it clear how the surface and subsurface flow within bed interact influence each other. order to clarify this issue we carried out two sets experiments, one involving velocity measurements in an impermeable composed a single layer spheres, another where velocities were measured made five such layers. Comparison statistics between experiments confirmed that permeability can significantly...

We investigate the turbulent structure of shallow open channel flows where flow depth is too small (compared with roughness height) to form a logarithmic layer but large enough develop an outer not directly influenced by elements. Since log present, displacement height d, which defines position zero plane, and shear velocity u* cannot be found fitting data law. However, these parameters are still very important because they used for scaling statistics layers. In this paper we propose...

A detailed experimental investigation of the hydrodynamics large-scale, bore-driven swash on impermeable, rough beach slopes is described. The experiments were carried out 1:10 with three different surface roughnesses based 1.3 mm sand, 5.4 gravel and 8.4 gravel. large-scale discrete event was produced by collapse a dambreak-generated bore beach. Simultaneous depths velocities measured using LIF, Laser-induced fluorescence, PIV, particle image velocimetry, respectively, yielding better...

This paper reports the double-averaged (in space and in time) hydrodynamic equations for mobile-boundary conditions that are derived based on refined double-averaging theorems, modified Reynolds decomposition, improved definitions of spatial time bed porosities. The obtained conservation provide a mathematical framework studying flows such as gravel rivers during flood events or over vegetated beds. These will help designing measurement campaigns obtaining mobile data their interpretation...

The performance of a number low-Reynolds turbulence models is evaluated against direct numerical simulations (DNS). All are applied to an unsteady flow comprising ramp-type excursion rate inside closed channel. increased linearly with time from initial Reynolds 9308 (based on hydraulic diameter and bulk velocity) final 29,650. acceleration varied cover low, intermediate high accelerations. It shown that among the investigated, k–ε Launder Sharma (1974) Chang et al. (1995) [28] γ–Reθ...

The extent to which turbulent structure is affected by bed-load transport investigated experimentally using a nonporous fixed planar bed comprising mixed-sized granular sediment with d50 of 1.95mm. Three different sizes (d50=0.77, 1.99, and 3.96mm) were fed into the flow at two rates (0.003 0.006kg∕m∕s), subsequently transported as load. Particle image velocimetry (PIV) was used determine turbulence characteristics over during clear water feed cases. Mean longitudinal velocities any given...

Abstract Sediment particles transported as bed load undergo alternating periods of motion and rest, particularly at weak flow intensity. Bed transport can be investigated by either following the individual (Lagrangian approach) or observing phenomenon prescribed locations (Eulerian approach). In this paper, Lagrangian Eulerian descriptions are merged into a unifying framework that includes definitions for quantities used to describe kinematics particle motion, well relationships among these...

This paper presents the results from an experimental study on turbulent flows through a regular porous matrix of spheres packed in cubic arrangement. The special pore geometry made it possible to measure velocity within individual pores, using ultrasonic profiler (UVP). UVP recorded time series average cross-sectional at points along pore. measurements were performed for various hydraulic gradients resulting Reynolds number between 70 and 430. Three different regimes detected: unsteady...

[1] Large-scale laboratory experiments presented in this paper involved bore-driven swash on permeable immobile coarse-grained beaches. Two different sediments were used (d50 = 1.5 and 8.5 mm) resulting beach permeability surface roughness. The yielded detailed measurements of depth velocities, wetting front, pressure, groundwater levels across the zone. This is focused processes occurring within beach. provide shape front table reveal behavior air unsaturated region Air initially at...

Abstract A numerical model solving the Reynolds‐Averaged Navier–Stokes equations, with a volume of fluid‐tracking scheme and turbulence closure, is employed for estimating hydrodynamics in swash zone. Model results run‐up distance, water depth, near‐bed velocity are highly correlated ( r 2 > 0.97) ensemble‐averaged dam‐break‐driven data. Moreover, modeled bed shear stresses within 20% estimates derived from measured profiles. Dam‐break‐driven simulations conducted to determine effect...

A detailed experimental investigation of the hydrodynamics large-scale, bore-driven swash on steep permeable, rough beaches is described.The experiments were carried out two but fixed beaches, made 1.3 mm sand and 8.4 gravel, respectively.The large-scale discrete event was produced by collapse a dam break-generated bore beach.Simultaneous depths velocities measured using laser-induced fluorescence (LIF), particle image velocimetry (PIV), respectively.Depth time series, instantaneous velocity...

Abstract Boundary layer dynamics are investigated using a 2‐D numerical model that solves the Volume‐Averaged Reynolds‐Averaged Navier‐Stokes equations, with VOF‐tracking scheme and k ‐ ϵ turbulence closure. The is validated highly resolved data of dam break driven swash flows over gravel impermeable permeable beds. spatial gradients velocity, bed shear stress, intensity terms reference to bottom boundary (BL) dynamics. Numerical results show mean vorticity responds flow...

We report new laboratory experiments of a flow accelerating from an initially turbulent state following the opening valve, together with large eddy simulations and extended Stokes first problem solutions for early stages flow. The results show that transient closely resembles laminar superimposed on original steady primary consequence acceleration is temporal growth boundary layer wall, gradually leading to strong instability causing transition. This extends findings previous direct...