Infrastructure Engineering - Research Publications
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ItemEffect of wind speed and direction on facade fire spread in an isolated rectangular building(Elsevier, 2022-05-01)This paper investigates the influence of wind speed and direction on external fire spread in an isolated rectangular building using computational fluid dynamics models validated with wind tunnel data and facade fire tests. Two wind speeds (2 m/s, 4 m/s) are considered for each of four wind directions (0°, 45°, 90°, 180°) and compared to a reference case of no wind. Results indicate that facade fire spread is heavily influenced by the near-wall flow fields generated by the building geometry. These flow fields explain counterintuitive findings such as the upstream tilting of flames under the influence of reverse flow near the side walls. The presence of external wind was found to inhibit the initial development of facade fires, but can greatly exacerbate fire spread once the fire has fully developed. The largest fire occurred for the case of no wind (7.5 GJ in 15 min) while the smallest fire occurred for the 4 m/s diagonal wind case (2.2 GJ). An additional case with temporally varying wind conditions demonstrated a 50% increase in fire spread area compared to no wind. The study provides valuable insight into wind and fire interaction in building facades that can help improve fire safety of buildings.
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ItemOptimising the computational domain size in CFD simulations of tall buildings(Elsevier, 2021-04-01)Recently, there has been a growing interest in utilizing computational fluid dynamics (CFD) for wind resistant design of tall buildings. A key factor that influences the accuracy and computational expense of CFD simulations is the size of the computational domain. In this paper, the effect of the computational domain on CFD predictions of wind loads on tall buildings is investigated with a series of sensitivity studies. Four distinct sources of domain error are identified which include wind-blocking effects caused by short upstream length, flow recirculation due to insufficient downstream length, global venturi effects due to large blockage ratios, and local venturi effects caused by insufficient clearance between the building and top and lateral domain boundaries. Domains based on computational wind engineering guidelines are found to be overly conservative when applied to tall buildings, resulting in uneconomic grids with a large cell count. A framework for optimizing the computational domain is proposed which is based on monitoring sensitivity of key output metrics to variations in domain dimensions. The findings of this paper help inform modellers of potential issues when optimizing the computational domain size for tall building simulations.
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ItemDesign of a smart prefabricated sanitising chamber for COVID-19 using computational fluid dynamics(Vilnius Gediminas Technical University Press, 2021-02-23)The novel coronavirus (SARS-CoV-2) has spread at an unprecedented rate, resulting in a global pandemic (COVID-19) that has strained healthcare systems and claimed many lives. Front-line healthcare workers are among the most at risk of contracting and spreading the virus due to close contact with infected patients and settings of high viral loads. To provide these workers with an extra layer of protection, the authors propose a low-cost, prefabricated, and portable sanitising chamber that sprays individuals with sanitising fluid to disinfect clothing and external surfaces on their person. The study discusses computer-aided design of the chamber to improve uniformity of sanitiser deposition and reduce discomfort due to excessive moisture. Advanced computational fluid dynamics is used to simulate the dispersion and deposition of spray particle, and the resulting wetting pattern on the treated person is used to optimise the chamber design.
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ItemImpact of atmospheric boundary layer inhomogeneity in CFD simulations of tall buildings(Elsevier BV, 2020-07)Recently, there has been a growing interest in utilizing computational fluid dynamics (CFD) for wind analysis of tall buildings. A key factor that influences the accuracy of CFD simulations in urban environments is the homogeneity of the atmospheric boundary layer (ABL). This paper aims to investigate solution inaccuracies in CFD simulations of tall buildings that are due to ABL inhomogeneity. The investigation involves two steps. In the first step, homogenous and inhomogeneous ABL conditions are generated in an empty computational domain by employing two different modelling approaches. In the second step, the homogenous and inhomogeneous conditions are each applied to an isolated tall building, and simulation results are compared to investigate impact of ABL inhomogeneity on wind load predictions. The study finds that ABL inhomogeneity can be a significant source of error and may compromise reliability of wind load predictions. The largest magnitude of inhomogeneity error occurred for pressure predictions on the windward building surface. Shortening the upstream domain length reduced inhomogeneity errors but increased errors due to wind-blocking effects. The study proposes a practical approach for detecting ABL inhomogeneity that is based on monitoring sensitivity of key output metrics to variations in upstream domain length.