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A novel discharge dispersion model is developed to simulate the complex three-dimensional flow behaviour of thermal-induced buoyant water jets under current-wave coexisting conditions. The model solved the governing fluid flow and energy equations for two immiscible and incompressible phases (water and air) which were weakly coupled by applying the Boberbeck-Boussinesq approximation. Different turbulence models, such as k−ε multiphase, k-ω SST, k-ω SST-multiphase, k-ω SST-stable, and realizable k−ε were applied. Extensive verification of the model's performance is conducted by comparing the developed model results against a diverse range of analytical and experimental data. First, a series of simulations are carried out to evaluate the performance of the model in reproducing the results of the wave hydrodynamic and interactions with the submerged trapezoid bar. This is followed by numerically replicating the experimental results of a vertical non-buoyant submerged jet under current-only and current-wave environments. Finally, the potency of the coupled hydro-thermal algorithm is assessed by validating against different thermal-induced buoyant submerged jet experimental tests. For this purpose, numerical prediction of the developed model is tested against physical experiments for a series of tests for thermal-induced buoyant submerged horizontal jets in stationary water and inclined thermal-induced buoyant water jet under the influence of current-wave environments. Results showed that the k-ω SST-multiphase provides the best agreement with the laboratory measured data in terms of flow, temperature distribution field, plume trajectory and dilution. The findings confirmed that the developed model can be used as a reliable tool in precisely modelling characteristic of thermal-induced buoyant water jet in shallow coastal waters.

Waterbodies’ thermal energy potential, as a green, renewable, and limitless source of energy, can be exploited in response to the growing energy demands of islands and coastal cities. Up to now, the technologies that have been developed for this purpose include seawater air-conditioning, surface water heat pump, and ocean energy thermal conversion systems or their combinations, which are presented here as Waterbodies Thermal Energy Based Systems (WTEBSs). The growth and development of these technologies raise concerns regarding their potential impacts on sustainability of the marine environment. The present work provides a comprehensive review of the available literature and state-of-the-art technologies describing potential interactions of WTEBSs throughout their life-cycle (i.e. including construction, installation, operation, and decommissioning) with the marine ecology. Modelling of seawater discharge dispersion as one of the main environmental impact concerns regarding the operation of WTEBSs is detailed and scopes for improving existing modelling tools are discussed. Potential destructive impacts of fouling and corrosion in WTEBSs are reported and deterrent recommendations are highlighted. Evidence of growth of bio-fouling inside of pipelines and associated mesh filtration baskets at abstraction pipe intakes are presented. The required permitting applications and licensing processes for installation and operation of WTEBSs by the relevant authorities are summarised. Finally, a summary of the findings from the data monitoring of water quality properties of a seawater air-conditioning pilot study performed at Brixham Laboratory, University of Plymouth, United Kingdom is reported.

The high-speed railway has become an important passenger transport mode. Relying on the abundant passenger transport experience and expansive railway network, the high-speed freight train (HSFT) is feasible to be developed and has great application potential. As a critical component of HSFT, the cargo plays an important role in the overturning safety of HSFT under strong wind conditions. Previous studies about the aerodynamic performance of the high-speed train usually regarded the loaded carbody as an individual rigid body. Limited attention was paid to the variability inside the vehicle. In order to improve the running safety of HSFT under strong wind conditions, the multibody dynamics simulation is adopted to demonstrate the effect of cargo property on the overturning risk of HSFT under the aerodynamic loads obtained through the computational fluid dynamics (CFD) simulations. It is demonstrated that the inner side crosswind is more dangerous than the outer side crosswind. The speed of HSFT should be limited according to the cargo quantity, and the maximum speed for a fully loaded HSFT can be 305 km/h when the crosswind velocity is 20 m/s. The larger cargo density should be encouraged because it is good for train overturning safety in severe working conditions.