Experience with the large eddy simulation (LES) technique for the modelling of premixed and non-premixed combustion

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Compared to RANS based combustion modelling, the Large Eddy Simulation (LES) technique has recently emerged as a more accurate and very adaptable technique in terms of handling complex turbulent interactions in combustion modelling problems. In this paper application of LES based combustion modelling technique and the validation of models in non-premixed and premixed situations are considered. Two well defined experimental configurations where high quality data are available for validation is considered as case studies to demonstrate the methods, accuracy and capability of the LES combustion modelling technique as a predictive tool. The large eddy simulation technique for the modelling flow and turbulence is based on the solution of governing equations for continuity and momentum in a structured Cartesian grid arrangement. Smagorinsky eddy viscosity model with a localised dynamic procedure is used as the sub-grid scale turbulence model. A swirl flame is considered as the nonpremixed combustion application. For non-premixed combustion modelling a conserved scalar mixture fraction based steady laminar flamelet model is used. A radiation model incorporating the discrete transfer method is also included in the non-premixed swirl flame calculations. For premixed combustion where the application considered here is flame propagation in a confined explosion chamber, a model based on dynamic flame surface density (DSFD) is used. It is shown that in both cases LES based combustion models perform remarkably well and results agree well with the experimental data.mp201

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

THEORETICAL AND EXPERIMENTAL STUDY OF MULTIMODAL TARGETED ENERGY TRANSFER IN A SYSTEM OF COUPLED OSCILLATORS

peer reviewedThe purpose of this study is the theoretical and experimental investigation of targeted energy transfers from a two-degree-of-freedom primary structure to a nonlinear energy sink (NES). It is demonstrated that an NES can resonate with and extract energy from both modes of the primary structure. By facilitating these energy transfers, notably through excitation of appropriate periodic and quasi-periodic orbits, one can promote dissipation of a major portion of externally induced energy in the nonlinear attachment

Changes in abundance and infectivity of powdery mildew conidia from cucumber plants treated systemically with lithium chloride.

Systemic treatment of cucumber plants with lithium chloride reduced the numbers of conidia produced by colonies of powdery mildew, Sphaerotheca fuliginea, growing on leaves, and lowered the infectivity of conidia produced from those leaves when they were applied to leaves of untreated plants. Production of conidiophores was lower in both lithium-treated and calcium-deprived plants, and lithium slightly decreased the calcium content of leaves. When the lithium-containing growth medium was supplemented with phosphate, conidiophore production was still markedly reduced, although leaves had normal levels of calcium. Fungal development was not correlated with either the calcium or phosphorus content of leaves. It is concluded that, although severe calcium deficiency can inhibit fungal development, the inhibitory effects of lithium are not mediated through alterations in calcium or phosphorus uptake by host tissues