1,721,551 research outputs found
Regular and Irregular Waves on a Sloping Beach
No full textTaking into account that many coastal processes, such as undertow currents, sedi-ment transport and action on maritime structures, are greatly affected by wave behav-iour, the aim of this paper is to investigate the hydrodynamics of both regular and irreg-ular waves. Hence, it illustrates the results of an experimental research carried out in two different laboratory wave flumes of the Water Engineering and Chemistry Depart-ment of Bari Technical University (Italy).
The first laboratory experiment examines the hydrodynamics of three different regular waves breaking on a fixed sloping bottom. The principal interest is therefore fo-cused on the wave behaviour in the surf zone.
The second experiment refers to an irregular wave characterized by a narrow banded spectrum and developing on a sloping sand bottom, in intermediate waters up to the surf zone. In this case, the shoaling region is thoroughly investigated in order to understand how the wave is affected by breaking induced turbulence.
In both experiments, the phase-averaging technique is used to extract the turbulent component from the time series of the acquired signal. This procedure is routinely used in laboratory studies when regular waves are studied. On the contrary, for irregular waves, it is not always assumed, being feasible only when some specific rules are re-spected, as occurred in the present study.
The analysis focused on the vertical profiles of time-averaged orbital velocities, wave and turbulent cross-correlations, turbulent kinetic energy, turbulent intensities. At the same time also the phase-averaged velocity components and turbulent kinetic energy were considered. Finally some considerations were derived for the transport of both turbulent kinetic energy and sediments, at various depths of each investigated location
Interdisciplinary Approach to Improve Agri-Food Safety and Quality
No full textThe agri-food sector is very broad and includes a whole series of steps in the supply chain ranging from agricultural production to the processing and marketing of final products [...
How obstructed jets experience detrainment
No full textA comprehensive understanding of turbulent jets discharged into obstructed environments remains a critical gap in the current literature. This issue holds significant importance for applications ranging from environmental fluid dynamics to industrial processes. The primary goal of this study is to theoretically investigate the dynamics of planar turbulent non-buoyant jets interacting with arrays of rigid obstacles, supported by a comparison between theoretical predictions and experimental data. Specifically, our analysis focuses on the entrainment process, revealing that obstructions in non-stratified flows impede entrainment, reversing it into detrainment. This finding is novel because (i) detrainment in natural settings is typically associated with buoyancy-driven flows, such as plumes or density currents in stratified environments, and (ii) to the best of the authors' knowledge, this is the first validation of theoretical entrainment coefficients with experimental data for obstructed non-buoyant jets. Experiments were conducted with turbulent non-buoyant jets using particle image velocimetry, providing detailed insights into flow structure and entrainment dynamics. Furthermore, the study explores jet particle dispersion and diffusivity through a Lagrangian framework. The results demonstrate significant differences in dispersion behavior between unobstructed and obstructed jets, showing that obstacle-induced blockage profoundly influences flow characteristics and jet detrainment. In particular, obstructions play a fundamental role, initially affecting the dispersion mechanism through obstacle diameter and later through the free spacing between obstacles. These findings provide valuable contributions to understanding flow physics in complex environments and have implications for engineering and environmental applications
- …
