The flow field near bridge piers is analysed using computational fluid dynamics (CFD) models to investigate bridge scour, which is one of the main safety concerns for bridges. Two indicators are used to characterise the scour hole, the horseshoe vortex (HV) core position relative to the bed, and the area of wall shear stress (WSS) above a sediment transport threshold of 1 Pa. The underlying fluid mechanics is detailed, establishing the relation between vorticity generation, the fluid strain rate and the WSS. The CFD models are validated against results in the literature, for the free surface around the pier and for the WSS at the bed. A parametric study with different pier widths, mass flow rates (MFR), and pier shapes is carried out, and these results are compared to an adapted pier with diverting fin inserted in the front. The adaptation shows that the diverting fin reduced the strength of the HV in front of the pier, and also reduces the total area of bed WSS above the threshold. ... Read more

The conservation of cultural heritage artefacts often requires particular conditions and a bespoke setup. We investigate the use of computational fluid dynamics (CFD) modelling to obtain high-resolution data of the present setup to conserve the SS Great Britain: the first iron-hulled screw-propelled ocean-going ship, preserved in its original dry dock in Bristol (UK). The conservation efforts focus on the dry air curtain to maintain the hull at low relative humidity to prevent corrosion, hence avoiding further degradation. The proposed computational model captures the key features, enabling the study of the air curtain efficacy, retaining an overall uncomplicated setup which is seen to be robust in a sensitivity analysis. The analysis of the transport of dry air focuses on the near-wall region, hence the interface between fluid and solid surface, in which exchange of species occurs, such as humidity and temperature. The near-wall fluid dynamics is described by the wall shear stress, divergence of wall shear stress, surface shear lines and wall shear stress critical points. The results provide a complete description of the flow near the hull surface and identify regions where the air curtain maintains adequate protection. The investigation highlights the use of air curtains on solid surfaces together with the analysis techniques necessary to describe the fluid dynamics. The modelling assumptions proposed are shown to be effective in investigating the air curtain. The solution to the computational model is compared to sensor data, showing good agreement on the ship's hull. ... Read more