This project intends to answer the following questions: Further research efforts, headed by the UK MoD, began following an incident where HMS Nottingham ran aground tearing a 50m hole from bow to bridge, flooding five compartments and almost causing the ship to sink just off Lord Howe Island in 2002. Due to the way the Estonia sank early research mainly focused on transient behaviour immediately after the damage takes place, the prediction of capsize, and of large lateral motions. Research into the behaviour of damaged ships began in the mid nineties as a result of Ro-Ro disasters (e.g. Through a combination of fundamental studies using wind tunnel experiments and high resolution supercomputer simulations, extensive data analysis and development of theoretical and numerical models, DIPLOS will contribute to addressing this difficult and important problem from both a scientific research and a practical, operational perspective.ĭominic Hudson, Ming-yi Tan (Investigators),Ĭhristian Wood, James Underwood, Adam SobeyĪn area of research currently of interest in the marine industry is the effect of damage on ship structures. Scientifically, this research is novel in focusing on localized releases within urban areas, and on dispersion processes at short range. Most of the existing research on urban dispersion has focused on air quality aspects, with sources being extensive and distributed in space. to implement them into an operational model, evaluate the improvement and apply the model to a case study in central London ![]() to enable these processes to be parametrized for use in operational models,ģ. to fill in the gaps in fundamental knowledge and understanding of key dispersion processes,Ģ. The contribution that DIPLOS will make is:ġ. However, this is precisely where current operational models are least reliable because our understanding and ability to model short-range dispersion processes is limited. In both these scenarios it is crucial to be able to model, quickly and reliably, dispersion from localised sources through an urban street network in the short range, where the threat to human health is greatest. The Buncefield depot fire of 2005 resulted in the evacuation of hundreds of homes and closure of more than 200 schools and public buildings for two days consequences would have been much more severe if prevailing meteorological conditions had promoted mixing or entrainment of the smoke plume into the urban canopy. Smoke from industrial accidents within or in the vicinity of urban areas also pose risks to health and can cause widespread disruption to businesses, public services and residents. Part of the risk posed by terrorist threats involves potential releases of air-borne chemical, biological, radiological or nuclear (CBRN) material into highly populated urbanised areas. The security threat level from international terrorism, introduced by the UK Security Service, has been classified as either "severe" or "critical" for much of its six-year history, and currently remains as "substantial" (source: MI5 website). Trevor Thomas, Ian Castro (Investigators) First attempts were tried in this route but time constraints limited the ultimate scope of the present work.ĭIPLOS - Dispersion of Localised Releases in a Street Network In order to demonstrate even greater advantages of non-linear models it was postulated that the addition of a streamwise impinging vortex hitting the leading edge of the cylinder would make the flow field fully three-dimensional. ![]() Although dome differences are observed, the prediction of the critical flow around a cylinder is not accurately achieved by any of these RANS models, but the FSM-?-?-EASM shows great resemblance with the validation data, demonstrating capabilities of resolving very complex flow phenomena with minimum user input if the computational grid is fine enough. In the visualisation of the results it is evident that the ?-?-EASM has greater flexibility estimating the components of the Reynolds stresses with respect to the baseline EASM and the k-?-SST. The flow predicting capabilities of the baseline EASM, ?-?-EASM and FSM-?-?-EASM tested are contrasted with the industrial renowned k-?-SST turbulence model. In this project the suitability of novel non-linear eddy viscosity closures and a hybrid Flow Simulation Methodology formulation to face these massively separated flows is studied. The mechanisms defining this critical flow state are very complex to predict computationally. At a certain characteristic Reynolds numbers the development of a turbulent wake occurs simultaneously with separation of the laminar boundary layer. The turbulent flow around a circular cylinder is a widely studied problem in fluid dynamics. ![]() ![]() Assessment of the performance of novel RANS and hybrid turbulence models on the flow around a cylinder
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