This experimental study is devoted to quantification of the near-bed turbulence characteristics at an entrainment threshold noncohesive sediments. Near bed, departure in distributions observed time-averaged streamwise velocity from logarithmic law more for immobile beds than entrainment-threshold beds. In Reynolds shear stress distributions, a damping that occurs near bed sediment higher Quadrant analysis reveals flow zone, ejections and sweeps on cancel each other, giving rise outward...

The time-averaged characteristics of turbulent wall-wake flows downstream a sphere placed on rough wall are studied. profiles the defect streamwise velocity, Reynolds shear stress, and turbulence intensities exhibit some degree similarities when they scaled by their respective peak values. For velocity profiles, vertical distances height location half-peak defect. However, for stress intensities, magnitudes all quantities diminish with distance characterizing recovery undisturbed profiles....

Double-averaged turbulence characteristics in a uniform flow over gravel bed are studied. The log-law for the velocity is preserved above interfacial sublayer, while within that sublayer follows polynomial law. Reynolds shear stress distribution roughness has considerable damping. A quadrant analysis suggests sweeps become prevalent mechanism sublayer. Within plots of form-induced velocities form tilted pseudo-elliptical shape, suggesting fluid undergoes cyclic process upward-streamwise...

This experimental and analytical study investigates the double-averaged (DA) turbulent flow characteristics within an array of large gravel obstacles found atop a porous bed. Analysis data reveals that DA streamwise velocity preserves logarithmic law above form-induced sublayer, while linear third-degree polynomial function apply interfacial sublayers, respectively. The shear stress is 70% Reynolds (RSS) occurring at virtual bed level. kinetic energy (TKE) components, vertical, attain their...

Abstract [1] Results of an experimental study on the effects bed injection (upward seepage from permeable bed) and suction (downward seepage) double-averaged (DA) turbulent flow characteristics over within interface gravel beds are presented. The DA Reynolds shear stress interfacial sublayer undergoes a higher damping with lesser injection, as compared to that no seepage. form-induced has decelerating effect accelerating injection. quadrant analysis suggests sweep events in flows ejection...

We perform a systematic study on the modulation of electroosmotic flow (EOF), tuning selectivity using electrolyte ions and hydrodynamic dispersion solute band across soft nanochannel. The supporting walls channel are considered to be hydrophobic bear non-zero surface charge. For such channel, inner side rigid coated with polyelectrolyte layer (PEL). inhomogeneous distribution monomers accompanying volume charge within PEL is modelled

The core-shell structured soft particles resemble various classes of bioparticles and environmental entities. presence the functional group within peripheral layer may lead to volumetric charge distribution. Besides, depending on Brinkmann screening length, shell allows penetration electrolyte ions, thus, classical ζ-potential loses its meaning for such composite comprehensive study electrophoretic motion is required. Considering importance, we made a systematic electrophoresis pH-regulated...

In this study, the experimental results of turbulent flow in a submerged, double-layered (an alternating combination shorter and taller plants staggered arrangement) rigid vegetation are analyzed with aim estimating kinetic energy (TKE) dissipation rate from perspective velocity structure functions. The entire domain is divided into three layers: Lower interfacial sublayer (LISL) consists lower portion plants, upper (UISL) extends up to top above main layer situated extending free surface....

Characteristics of turbulent mixing-length, length scales and anisotropy in the wall-wake flow downstream a sphere placed on rough wall are studied. The Prandtl's mixing-length increases compared to that upstream flow, while Taylor microscale Kolmogorov scale decrease. As distance increases, defects (difference between distributions) vertical distributions gradually disappear recover their undisturbed flow. These exhibit some degree similarity, as they scaled by individual peak values is...

This study examines the turbulence in wall-wake flow downstream of an isolated dunal bedform. The streamwise velocity and Reynolds shear stress profiles at upstream various distances dune were obtained. results reveal that flow, third-order moments change their signs below crest, whereas remain unaltered above crest. near-wake is featured by sweep events, far-wake controlled ejection events. Downstream dune, turbulent kinetic energy production dissipation rates, near-bed zone, are positive....

The time-averaged turbulent flow characteristics in a wall-wake downstream of wall-mounted vertical cylinder (free-surface piercing) are analyzed from the viewpoint self-similarity their profiles. In flow, deficits (differences between upstream and values at given elevation) streamwise velocity, Reynolds shear stress, turbulence intensities, third-order moments exhibit certain degree profiles when they scaled by respective maximum deficit values. For scaling distance to achieve...

Image analysis has been increasingly used for the measurement of river flows due to its capabilities furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application particle tracking velocimetry (PTV) bed-load experiment with lightweight sediment. The key characteristics investigated sediment transport conditions were presence covered flow and fixed rough bed above which particles released in limited number flume inlet. Under applied conditions,...

ABSTRACT This study attempts to extend previous research on electrokinetic turbulence (EKT) in Oldroyd‐B fluid by investigating the relationship between Weissenberg number () and second‐order velocity structure function under applied electric fields. Inspired Sasmal's demonstration Sasmal (2022) of how heterogeneous zeta potentials induce above a critical , we develop mathematical framework linking turbulent phenomena. Our analysis incorporates recent findings AC (Zhao & Wang, 2017) DC...

Abstract The paper presents the experimental results of turbulent flow over hydraulically smooth and rough beds. Experiments were conducted in a rectangular flume under aspect ratio b/h = 2 (b width channel 0.5 m, h depth 0.25 m) for both bed conditions. For bed, roughness was created by using 3/8″ commercially available angular crushed stone chips; whereas sand median diameter d 50 1.9 mm used as material bed. three-dimensional velocity components captured Vectrino (an acoustic Doppler...

The turbulence anisotropy in flow over noncohesive sediment beds at an entrainment threshold, as compared to that immobile beds, is studied. streamwise component of tensor near-bed for threshold yields more anisotropic stream whereas all other components yield less stream. invariant maps illustrate the layer tending be a two-component isotropy both and beds. data plots with increase vertical distance have affinity one-component isotropy, those mobile show tendency become three-dimensional...

A theoretical study has been carried out on the electrophoresis of charged dielectric liquid droplets with an equipotential and hydrodynamically slipping surface moving in a quenched polymeric hydrogel medium. The inside droplet is electrically neutral. Brinkman-Debye-Bueche model employed to gel such hydrophobic considering long-range hydrodynamic interaction between migrating skeleton. Within weak field Debye-Hückel electrostatic framework, we derive original closed-form expression for...

Experimental investigations of flow past two (one above other) horizontal cylinders have been presented in this paper. The experimental data captured over a rough-bed with double having three different diameters, were used for the analysis. Firstly, general characteristics such as streamwise velocity, Reynolds shear stress and turbulence intensity profiles elucidated at downstream locations from cylinder position; then some advanced analysis length scales, turbulent kinetic energy (TKE)...

Image analysis has been increasingly used for the measurement of river flows due to its capabilities furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application particle tracking velocimetry (PTV) bed-load experiment with lightweight sediment. The key characteristics investigated sediment transport conditions were presence covered flow and fixed rough bed above which particles released in limited number flume inlet. Under applied conditions,...

This article presents experimental results of turbulent flow measured in a bimodal degraded channel bed consisting sand-gravel mixture. Sand and gravel uniform sizes 0.25 3.5 mm were mixed the same proportions (by weight) to create sedimentary bed. A three-dimensional Vectrino velocimeter was employed collect velocities over under equilibrium condition. The streamwise velocity, Reynolds stresses, kinetic energy (TKE), TKE fluxes profiles compared with literature. However, advancement...

The present study focuses on the time-averaged turbulence characteristics over a highly spatially-heterogeneous gravel-bed. timeaveraged streamwise velocity, Reynolds shear and normal stresses, turbulent kinetic energy, higher-order moments of velocity fluctuations, length scales, bursting were measured gravel-bed with an array larger gravels. It was observed that do not vary significantly above crest level as compared to those below array. nondimensional decreases considerably decrease in...