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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 surface acoustic waves (SAW) propagate inside the microdroplets resulting in kinetic and thermal impacts. The kinetic drives fluid particles inside the droplet while thermal impact increases the liquid’s temperature. This paper provides a comprehensive review of the research investigations related to internal kinetics and heating inside the microdroplet caused by the acoustic waves. The main factors that affect the kinetics and convection heat transfer are the piezoelectric materials, shape of the interdigital transducer (IDT) and mode of acoustic waves. Internal streaming (kinetic) leads to particle mixing, particle manipulation, cell sorting, cell patterning, cell separation, measuring the concentration of immunoglobulin and so forth. The effect of changing the mode of waves and the shape of IDT on the relevant applications are presented. Internal convection heat transfer is important where heating of the liquid is essential for many applications such as monitoring blood coagulation in the human plasma and an acoustic tweezer for particle trapping. Experimental methods developed by researchers to realise uniform temperature with constant heating and cooling cycles are also discussed. Such methods are widely used in the polymerase chain reaction (PCR) to detect COVID-19 infection. The heating of the droplet can be efficiently controlled by changing the input power and by varying the duty factor.