Particle trajectories in linearized irrotational shallow water flows

We investigate the particle trajectories in an irrotational shallow water flow over a flat bed as periodic waves propagate on the water's free surface. Within the linear water wave theory, we show that there are no closed orbits for the water particles beneath the irrotational shallow water waves. Depending on the strength of underlying uniform current, we obtain that some particle trajectories are undulating path to the right or to the left, some are looping curves with a drift to the right and others are parabolic curves or curves which have only one loop

Earthworks risk assessment on a heritage railway

The UK is home to a substantial number of heritage and tourist railways, which make a significant contribution to their local economies. They are mostly constructed on the routes of closed lines, and include large numbers of earthworks of uncertain construction and unknown strength. Recently, there have been earthwork collapses, most notably on the Gloucester and Warwickshire Railway during 2010 and 2011. The Office of Rail Regulation has also noted a number of safety incidents on heritage railways, all attributable to management failures. This paper describes an analysis of the Victorian earthworks on the Bo'ness and Kinneil Railway, a 8 km-long heritage railway in central Scotland. The analysis and risk prioritisation method used by Network Rail was found to be unsuitable for direct application to heritage railways, owing to the different operating context. A new system was therefore developed, removing some risk factors from the Network Rail approach, adding others, and modifying further ones. The new system was successfully applied, and the Bo'ness and Kinneil Railway earthworks were found to be generally stable and safe

Progression of Wave Breaker Types on a Plane Impermeable Slope, Depending on Experimental Design

M. V. Moragues was supported by the research group TEP-209 (Junta de Andalucia) and by the following projects: "Protection of coastal urban fronts against global warming-PROTOCOL" (917PTE0538), "Integrated verification of the hydrodynamic and structural behavior of a breakwater and its implications on the investment project-VIVALDI" (BIA2015-65598-P). This work was funded by the projects PCI2019-103565-SUSME and PID2019-107509GB-I00-ROMPEOLAS (SRA (State Research Agency)/10.13039/501100011033). M. A. Losada was partially funded by the emeritus professorship mentoring program of the University of Granada. We would like to thank the three reviewers for providing helpful comments on earlier drafts of the manuscript.The objective of this research was to analyze the progression of breaker types on plane impermeable slopes. This study used dimensional analysis to demonstrate the relative water depth is a key explanatory quantity. The dominant breaker types depend on the incident wave characteristics at the foot of the slope. Accordingly, it is possible to combine values of H, T, and m. The physical experiments of Galvin, recent numerical results, and new experiments, performed on an impermeable 1:10 slope, were used to verify the result. It was thus possible to obtain the progression of breaker types in different sequences of pairs of combined wave H and T values. Once a sequence is defined, the expected progression of breaker types is predictable, and is well approximated by the log-transform of the alternate similarity parameter. Since the classification of breaker types is discontinuous, the data assigned to each type were placed in horizontal lines, based on the value of log(chi). Given that the breaking of a wave train on a slope should be considered a continuous process, the location of some data was corrected to satisfy this assumption. There is thus a functional relationship between the sets of the experimental space and of the breaker types. This research also derives the non-dimensional energy dissipation on the slope, considering the wave-reflected energy flux on the slope. It is proportional to a dimensionless bulk dissipation coefficient which depends on the breaker type and, therefore, on the value of chi at the toe of the slope.Junta de Andalucia 917PTE0538 BIA2015-65598-Pemeritus professorship mentoring program of the University of GranadaPCI2019-103565-SUSMEPID2019-107509GB-I00-ROMPEOLAS10.13039/50110001103

Stationary rotary force waves on the liquid–air core interface of a swirl atomizer

A one-dimensional wave equation, applicable to the waves on the surface of the air-core of a swirl atomizer is derived analytically, by analogy to the similar one-dimensional wave equation derivation for shallowwater gravity waves. In addition an analogy to the flow of water over a weir is used to produce an analytical derivation of the flow over the lip of the outlet of a swirl atomizer using the principle of maximum flow. The principle of maximum flow is substantiated by reference to continuity of the discharge in the direction of streaming. For shallowwater gravity waves, the phase velocity is the same expression as for the critical velocity over the weir. Similarly, in the present work, the wave phase velocity on the surface of the air-core is shown to be the same expression as for the critical velocity for the flow at the outlet. In addition, this wave phase velocity is shown to be the square root of the product of the radial acceleration and the liquid thickness, as analogous with the wave phase velocity for shallow water gravity waves, which is the square root of the product of the acceleration due to gravity and the water depth. The work revisits the weirs and flumes work of Binnie et al. but using a different methodology. The results corroborate with the work of Binnie. High speed video, Laser Doppler Anemometry and deflected laser beam experimental work has been carried out on an oversize Perspex (Plexiglas) swirl atomizer. Three distinctive types of waves were detected: helical striations, low amplitude random ripples and low frequency stationary waves. It is the latter wave type that is considered further in this article. The experimentally observed waves appear to be stationary upon the axially moving flow. The mathematical analysis allows for the possibility of a negative value for the phase velocity expression. Therefore the critical velocity and the wave phase velocity do indeed lead to stationary waves in the atomizer. A quantitative comparison between the analytically derived wave phase velocity and that measured experimentally, for this stationary pulsating wave, show very good agreement within a few percent

Experimental aluminum pathology in rabbits: effects of hydrophilic and lipophilic compounds.

Aluminum lactate [Al(lact)3] (hydrophilic, hydrolytically unstable) and aluminum acetylacetonate [Al(acae)3] (lipophilic, hydrolytically stable) were tested as potential toxicants to rabbits upon IV administration both as aqueous solutions and as liposome suspensions. Both chemicals behaved as cardiotoxic agents when administered as aqueous solutions, but Al(acae)3 was at least two orders of magnitude more active than Al(lact)3. Al(acae)3, but not Al(lact)3, caused myocardial infarcts resembling those in humans (with contraction bands) at doses as low as 0.24 mg/kg body weight, as well as a prominent acanthocytosis. Al(lact)3, when administered as a liposome suspension, was about 300 times more toxic than in aqueous solution, although cardiac damage was not infarctual in character. Both chemical and physical speciation of aluminum(III) thus play an essential role in determining the toxicity of the metal

Wave patterns generated by an axisymmetric obstacle in a two-layer flow

Gravity waves generated by a moving obstacle in a two-layer stratified fluid are investigated. The experimental configuration is three-dimensional with an axisymmetric obstacle which is towed in one of the two layers. The experimental method used in the present study is based on a stereoscopic technique allowing the 3D reconstruction of the interface between the two layers. Investigation into the wave pattern as a function of the Froude number, Fr, based on the relative density of the fluid layers and the velocity of the towed obstacle is presented. Specific attention is paid to the transcritical regime for which Fr is close to one. Potential energy trapped in the wave field patterns is also extracted from the experimental results and is analyzed as a function of both the Froude number, Fr, and the transcritical similarity parameter Γ. In particular, a remarkable increase in the potential energy around Fr = 1 is observed and a scaling allowing to assemble data resulting from different experimental parameters is proposed

Overview of JET results for optimising ITER operation

The JET 2019–2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power in 2019–2020, and tested the technical and procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle (α) physics in the coming D–T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed shattered pellet injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design and operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D–T benefited from the highest D–D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER

New H-mode regimes with small ELMs and high thermal confinement in the Joint European Torus

New H-mode regimes with high confinement, low core impurity accumulation, and small edge-localized mode perturbations have been obtained in magnetically confined plasmas at the Joint European Torus tokamak. Such regimes are achieved by means of optimized particle fueling conditions at high input power, current, and magnetic field, which lead to a self-organized state with a strong increase in rotation and ion temperature and a decrease in the edge density. An interplay between core and edge plasma regions leads to reduced turbulence levels and outward impurity convection. These results pave the way to an attractive alternative to the standard plasmas considered for fusion energy generation in a tokamak with a metallic wall environment such as the ones expected in ITER.& nbsp;Published under an exclusive license by AIP Publishing

Shattered pellet injection experiments at JET in support of the ITER disruption mitigation system design

A series of experiments have been executed at JET to assess the efficacy of the newly installed shattered pellet injection (SPI) system in mitigating the effects of disruptions. Issues, important for the ITER disruption mitigation system, such as thermal load mitigation, avoidance of runaway electron (RE) formation, radiation asymmetries during thermal quench mitigation, electromagnetic load control and RE energy dissipation have been addressed over a large parameter range. The efficiency of the mitigation has been examined for the various SPI injection strategies. The paper summarises the results from these JET SPI experiments and discusses their implications for the ITER disruption mitigation scheme