In open channel, canals and rivers, a rapid increase in flow depth will induce a positive surge, also called bore or compression wave. The positive surge is a translating hydraulic jump. Herein new experiments were conducted in a large-size rectangular channel to characterise the unsteady turbulent properties, including the coupling between free-surface and velocity fluctuations. Experiments we...

High-velocity free-surface flows are complex two-phase flows and limited information is available about the interactions between air and water for void fractions of about 50%. Herein a detailed experimental study was conducted in the intermediate flow region ( C ∼ 50%) on a stepped spillway and the microscopic air–water flow characteristics were investigated. The results showed differences in w...

to enhance the understanding of the impact of obstacle buildings on pollution transportationand dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using computational fluid dynamics ...

Effect of altitude is discussed in the unsteady separation of multi stage rockets. Axisymmetric, unsteady and turbulent Navier stokes equations are solved numerically. The governing equations are split into a hyperbolic inviscid part and a parabolic diffusion part. The hyperbolic part is solved by an explicit second-order time and space of Godunov-type scheme. Moving mesh and moving boundary al...

in this study, the dispersion mechanisms of aerosols suspended in a turbulent plane channel flow is investigated using a novel numerical approach. a turbulent channel flow is simulated by a direct numerical simulation (dns) method, for which no-slip boundary conditions are assumed at the top and bottom walls, while periodicity conditions are applied on the other sides. dns, in particular, allow...

In an open channel, a hydraulic jump is a sudden transition from a high-velocity to slower, fluvial flow motion. The impinging flow forms a turbulent roller with a highly fluctuating free-surface, while a large amount of air bubbles is entrapped at the jump toe. The present work presents some physical investigations of hydraulic jumps based upon a wide range of inflow Froude numbers (3.8 < Fr1 ...

Properties of turbulence, such as the direction of the energy cascade depend on the flow dimensionality. Recent experimental results reveal new physics understanding of flows in thick layers. We show that the flow dimensionality can be characterized by the flow damping and that a comparison of the decay rate with that of a quasi-2D flow can be used as a measure of dimensionality of a turbulent ...

turbulence structure on the gas side of a wavy stratified flow was experimentally investigated in a near horizontal 18.7 cm (h) 10 cm (w) 5.5m (l) rectangular duct.by applying the variable interval time averaging (vita) technique to the hot wire anemometer measurements frequency of occurrence of turbulent events were detected near the air-water interface. experimental results showed that freque...

Motivated by observations of the subglacial drainage of water, we consider a hydraulic fracture problem in which the crack grows parallel to a free surface, subject to fully turbulent fluid flow. Using a hybrid Chebyshev=series-minimization numerical approach, we solve for the pressure profile, crack opening displacement, and crack growth rate for a crack that begins relatively short but eventu...

This paper represents a first step towards the development of two-phase CFD methods for small and large scale ship hydrodynamic applications. Two-phase level set approaches are being implemented in CFDShip-Iowa to extend the modeling capabilities of the current version 4 along with complementary experiments for validation. The experiments are conducted in an open channel flume using bottom moun...