Parallel adaptive weakly-compressible SPH for complex moving geometries

The use of adaptive spatial resolution to simulate flows of practical interest using Smoothed Particle Hydrodynamics (SPH) is of considerable importance. Recently, Muta and Ramachandran [1] have proposed an efficient adaptive SPH method which is capable of handling large changes in particle resolution. This allows the authors to simulate problems with much fewer particles than was possible earlier. The method was not demonstrated or tested with moving bodies or multiple bodies. In addition, the original method employed a large number of background particles to determine the spatial resolution of the fluid particles. In the present work we establish the formulation's effectiveness for simulating flow around stationary and moving geometries. We eliminate the need for the background particles in order to specify the geometry-based or solution-based adaptivity and we discuss the algorithms employed in detail. We consider a variety of benchmark problems, including the flow past two stationary cylinders, flow past different NACA airfoils at a range of Reynolds numbers, a moving square at various Reynolds numbers, and the flow past an oscillating cylinder. We also demonstrate different types of motions using single and multiple bodies. The source code is made available under an open source license, and our results are reproducible.Comment: 50 pages, 22 figures, 3 tables. Updated one figure (Fig. 9

Slope Stability Assessment and Underground Mine Design Analysis of Achibo-Sombo Underground Conventional Coal Mine, Southwest Ethiopia

We report the slope stability assessment and underground mine design analysis results for the first of its kind conventional Achibo-Sombo underground coal mine from Ethiopia. Based on the RQD, RMR and Q classification system, the rocks in the mine are of poor to fair rock quality and are classified into category I (25 MPa). Joint space and aperture are ranging from few mm to cm with E-W, NNW-SSE and N-S orientations and low to very low persistence from 50 cm to 2 m. The factor of safety calculated using CMRI, Salamon-Munro, Greenwald, Obert and Duvall, and Bieniawsk methods for the existing pillars for category I is 1.37, 4.39, 2.21, 3.58, 4.76; category II 2.25, 4.39, 7.76, 12.52, 16.72; and category III 3.21, 4.39, 13.72, 22.26, 29.58 respectively. The factor of safety calculated again for the newly proposed design using the same methods is 1.05, 3.83, 1.91, 2.99, 3.8 for category I; 1.65, 3.17, 5.48, 8.55, 10.02 for category II and 2.20, 2.63, 7.91, 8.26, 14.25 for category III respectively. The extraction percentage has increased from 24.2 % (for the existing) to 31%, 41% and 52% for I, II and III categories respectively

Slope Stability Assessment and Underground Mine Design Analysis of Achibo-Sombo Underground Conventional Coal Mine, Southwest Ethiopia

We report the slope stability assessment and underground mine design analysis results for the first of its kind conventional Achibo-Sombo underground coal mine from Ethiopia. Based on the RQD, RMR and Q classification system, the rocks in the mine are of poor to fair rock quality and are classified into category I (25 MPa). Joint space and aperture are ranging from few mm to cm with E-W, NNW-SSE and N-S orientations and low to very low persistence from 50 cm to 2 m. The factor of safety calculated using CMRI, Salamon-Munro, Greenwald, Obert and Duvall, and Bieniawsk methods for the existing pillars for category I is 1.37, 4.39, 2.21, 3.58, 4.76; category II 2.25, 4.39, 7.76, 12.52, 16.72; and category III 3.21, 4.39, 13.72, 22.26, 29.58 respectively. The factor of safety calculated again for the newly proposed design using the same methods is 1.05, 3.83, 1.91, 2.99, 3.8 for category I; 1.65, 3.17, 5.48, 8.55, 10.02 for category II and 2.20, 2.63, 7.91, 8.26, 14.25 for category III respectively. The extraction percentage has increased from 24.2 % (for the existing) to 31%, 41% and 52% for I, II and III categories respectively

Mapping geographical inequalities in access to drinking water and sanitation facilities in low-income and middle-income countries, 2000–17

Abstract Background: Universal access to safe drinking water and sanitation facilities is an essential human right, recognised in the Sustainable Development Goals as crucial for preventing disease and improving human wellbeing. Comprehensive, high-resolution estimates are important to inform progress towards achieving this goal. We aimed to produce high-resolution geospatial estimates of access to drinking water and sanitation facilities. Methods: We used a Bayesian geostatistical model and data from 600 sources across more than 88 low-income and middle-income countries (LMICs) to estimate access to drinking water and sanitation facilities on continuous continent-wide surfaces from 2000 to 2017, and aggregated results to policy-relevant administrative units. We estimated mutually exclusive and collectively exhaustive subcategories of facilities for drinking water (piped water on or off premises, other improved facilities, unimproved, and surface water) and sanitation facilities (septic or sewer sanitation, other improved, unimproved, and open defecation) with use of ordinal regression. We also estimated the number of diarrhoeal deaths in children younger than 5 years attributed to unsafe facilities and estimated deaths that were averted by increased access to safe facilities in 2017, and analysed geographical inequality in access within LMICs. Findings: Across LMICs, access to both piped water and improved water overall increased between 2000 and 2017, with progress varying spatially. For piped water, the safest water facility type, access increased from 40·0% (95% uncertainty interval [UI] 39·4–40·7) to 50·3% (50·0–50·5), but was lowest in sub-Saharan Africa, where access to piped water was mostly concentrated in urban centres. Access to both sewer or septic sanitation and improved sanitation overall also increased across all LMICs during the study period. For sewer or septic sanitation, access was 46·3% (95% UI 46·1–46·5) in 2017, compared with 28·7% (28·5–29·0) in 2000. Although some units improved access to the safest drinking water or sanitation facilities since 2000, a large absolute number of people continued to not have access in several units with high access to such facilities (>80%) in 2017. More than 253 000 people did not have access to sewer or septic sanitation facilities in the city of Harare, Zimbabwe, despite 88·6% (95% UI 87·2–89·7) access overall. Many units were able to transition from the least safe facilities in 2000 to safe facilities by 2017; for units in which populations primarily practised open defecation in 2000, 686 (95% UI 664–711) of the 1830 (1797–1863) units transitioned to the use of improved sanitation. Geographical disparities in access to improved water across units decreased in 76·1% (95% UI 71·6–80·7) of countries from 2000 to 2017, and in 53·9% (50·6–59·6) of countries for access to improved sanitation, but remained evident subnationally in most countries in 2017. Interpretation: Our estimates, combined with geospatial trends in diarrhoeal burden, identify where efforts to increase access to safe drinking water and sanitation facilities are most needed. By highlighting areas with successful approaches or in need of targeted interventions, our estimates can enable precision public health to effectively progress towards universal access to safe water and sanitation