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

Abstract 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

The effect of lateral channel contraction on dam break flows: Laboratory experiment

This paper presents an investigation of dam break flow in a channel with lateral contraction. An experiment was carried out in a laboratory flume by instantaneous removal of a plate. The problem was studied in a smooth prismatic channel of rectangular cross-section over horizontal dry bed. At a certain distance downstream from the dam location, two symmetrical triangular-shaped lateral sidewall obstacles were installed to generate converging-diverging channel reach. Thus, it points out the abrupt variation of topography in floodplain for practical applications. Adopted measuring technique, digital image processing, detected the flood wave propagation quite well thereby synchronous recording of the flow through the entire channel with three cameras. The continuous free surface profiles and stage hydrographs were obtained without disturbing the flow. The experimental data were compared with the results of RANS-based numerical simulation. Comparisons between measured and computed results show good agreement. © 2012 Elsevier B.V.MMF2007BAP6This work was partly supported by Cukurova University Research Fund under Project No.: MMF2007BAP6. This support is gratefully acknowledged

Dam-break flows during initial stage using SWE and RANS approaches

Experimental and numerical results relating to dam-break flows are compared. Dam-break waves were generated by the quasi-instantaneous removal of a plate in a smooth prismatic channel of rectangular cross-section over horizontal dry and wet beds. The laboratory experiments were conducted to determine the initial stages of the free surface profiles using digital image processing. The flow characteristics were detected by applying an adequate, simple and economical measuring technique. The experimental results were compared with the results of a commercially available CFD program, solving the Reynolds-averaged Navier-Stokes (RANS) equations with the k- turbulence model involving the shallow-water equations. Measured and computed free surface profiles during the initial dam-break stages indicate that although both models predict the dam-break flow with a reasonable accuracy, the agreement using the RANS model is better. © 2010 International Association for Hydro-Environment Engineering and Research

Investigation of dam-break induced shock waves impact on a vertical wall

In the present study, experimental tests and VOF-based CFD simulations concerning impact of dam-break induced shock waves on a vertical wall at downstream end were investigated. New laboratory experiments were carried out in a rectangular flume with a smooth horizontal wet bed for two different tailwater levels. Image processing was used for flow measurement and time evolutions of water levels were determined effectively by means of synchronous recorded video images of the flow. This study scrutinized formation and travelling of negative wave towards upstream direction, which was resulted from the reflection of flood wave against downstream end wall. In numerical simulation, two distinct approaches available in FLOW-3D were used: Reynolds- averaged Navier-Stokes equations (RANS) with the k-? turbulence model and the Shallow Water Equations (SWEs). The measured results were then compared with those of numerical simulations and reasonable agreements were achieved. General agreement between laboratory measurements and RANS solution was better than that of SWE. © 2015 Elsevier B.V

Dam-break flow in the presence of obstacle: Experiment and CFD simulation

The aim of this paper is to present an experimental and numerical investigation of dam-break flow over initially dry bed with a bottom obstacle. This test case highlights not only the bottom slope effects but also those of abrupt change in channel topography. Dam-break flow was applied in a smooth prismatic channel of rectangular cross-section over a trapezoidal bottom sill on the downstream bed. The present study scrutinized the formation and propagation of negative bore behind the sill. The flow was numerically simulated by the VOF-based commercially available CFD program, Flow-3D, solving the Reynolds Averaged Navier Stokes equations with the k-? turbulence model (RANS) and the Shallow Water Equations (SWE). To validate CFD models an experiment was carried out. Using an advanced measuring technique, digital image processing, the flow was recorded simply through the glass walls of channel; thus, continuous free surface profiles were acquired synchronously with three cameras along the channel. The adopted measuring technique is non-intrusive and yields accurate and valuable results without flow disturbances. Comparison of the computed results with experimental data shows that RANS model reproduces the flow under investigation with reasonable accuracy while simple SWE model indicates some discrepancies particularly in predicting the negative wave propagation.MMF2007BAP6This work was partly supported by Cukurova University Research Fund under project no: MMF2007BAP6. This support is gratefully acknowledged

Investigation of dam-break flow over abruptly contracting channel with trapezoidal-shaped lateral obstacles

The present paper aims to investigate the dam-break flow over dry channel with an abrupt contracting part in certain downstream section. A new experiment was carried out in a smooth-prismatic channel with rectangular cross section and horizontal bed. A digital imaging technique was adopted for flow measurement and thus flood wave propagation was sensitively obtained. Synchronous filmed images of the dam-break flow were nonintrusively acquired with three cameras, through glass sidewalls of the channel. Free surface profiles and time evolution of water levels were derived directly from the recorded video images using virtual wave probe without disturbing the flow. Furthermore, the present study highlights the formation and propagation of the negative bore due to abruptly contracting channel. The measured results were compared with the numerical solution of Reynolds averaged Navier-Stokes (RANS) equations with k-turbulence model and good agreement was achieved. New experimental data can be useful for scientific community to validate numerical models. © 2012 American Society of Mechanical Engineers

Investigation of dam-break flood waves in a dry channel with a hump

Dam-break represents a potential flood hazard for population at downstream due to the sudden release of the water stored in the reservoir. The prediction of dam-break wave parameters is complicated furthermore by the presence of irregularities in the channel. This paper aims to present an experiment and numerical simulations of dam-break flood wave in an initially dry flume with a hump. A triangular-shaped bottom obstacle was placed downstream the dam site in the channel to provide the effects of both bottom slope and abrupt change in topography on propagation of dam-break flood waves. A new experiment was carried out in a smooth rectangular cross-section channel by using digital image processing. Flow behaviour was synchronously recorded with three adjacent CCD cameras through the glass walls of the entire downstream channel. This adopted measuring technique eliminates the necessity for test repetition due to capturing the whole flow field at once. Not only continuous free surface profiles at various times but also time evolutions of the water levels for selected locations were simply acquired from the video records of the image processing by virtual wave probe. Furthermore, dam-break flow was numerically simulated by the VOF-based CFD commercial software package FLOW-3D, which utilizes two distinct approaches, namely the Reynolds-averaged Navier-Stokes equations (RANS) with a k-? turbulence model and the simple Shallow Water Equations (SWEs). Comparison between the computed results and the experimental data shows that both numerical models reproduce the flow behaviour with reasonable accuracy and the agreement is slightly better in RANS model compared to simple SWE model. Current experimental data can be useful for validation of other numerical models. © 2014 International Association for Hydro-environment Engineering and Research, Asia Pacific Division

Experimental and numerical investigation of shock wave propagation due to dam-break over a wet channel

We investigated the propagation of shock waves in a prismatic rectangular channel with a horizontal wet bed. Saltwater was used as a Newtonian fluid within the entire channel instead of normal water for representing the different density fluids. It aims to point out seawater where tsunamis occur as an extreme example of shock waves. The shock waves were generated by sudden lifting of a vertical gate that separated a reservoir and a downstream channel with three different tailwater depths. The experimental data were digitized using image processing techniques. Furthermore, the flow was numerically solved by using Reynolds Averaged Navier-Stokes (RANS) equations and a DualSPHysics program (a code version of smoothed particle hydrodynamics (SPH)). After sudden removal of the vertical gate the propagations of shock waves were experimentally examined via image processing, which can yield both free surface profiles at several times and variations of flow depth with time at four specified locations. Solution successes of two different numerical methods for this rapidly varied unsteady flow are tested by comparing the laboratory data. The results indicate that the disagreements on graphs of time evolutions of water levels obtained from two numerical simulations decrease when the initial tailwater levels increase. © 2019, HARD Publishing Company. All rights reserved.This study was supported by Cukurova University Research Fund Project No. FDK-2015-4887. The authors gratefully acknowledge this support

Modeling flood shock wave propagation with the smoothed particle hydrodynamics (SPH) method: An experimental comparison study

The applicability of experimental and numerical models used for the solution of dam-break flows is vital for better dam projects and also in preventing related accidents. The high cost and the time-consuming nature of laboratory studies require consistency in the investigation of numerical models. In this study, the propagation of a flow using a fluid with a different density from that of normal water in the reservoir was investigated both experimentally and numerically. Salt water was preferred as a Newtonian fluid in order to observe the propagation of flows in different density after a sudden break. A small-scale channel was constructed and laboratory data were obtained using image processing techniques. For the numerical model, Smoothed-Particle Hydrodynamics (SPH) method and Reynolds Averaged Navier-Stokes (RANS) equations solved by Flow-3D software, were applied. Flow depth changes were observed in the reservoir and the downstream. The data obtained from all methods were compared with each other. The results of two numerical simulations point out that the disagreements on graphs in the time evolutions of the fluid levels in the SPH increase due to turbulence effects, whilst, these differences decrease in the RANS equations solved by Flow-3D software. Consequently, since the SPH provides taking the measures and developing intervention strategies to reduce the risks connected to the evolution of dam-break flows, it is thought that future validation studies of the model will be require with the use of data observed in this field. © 2019, ALÖKI Kft., Budapest, Hungary.Firat University Scientific Research Projects Management Unit: FDK-2015-4887Acknowledgements. This study was supported by Çukurova University Scientific Research Projects Unit with the project code of FDK-2015-4887. The authors would like to thank Çukurova University Scientific Research Projects Unit on account of providing and helping in this research