Laboratory experiments evaluating sedimentation and mound formation of obliquely discharged sand particles in stagnant water |
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| Affiliation: | 1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, 100048, China;2. Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China;1. Department of Civil and Environmental Engineering, University of California, Davis, 2001 Ghausi Hall, One Shields Ave., Davis, CA 95616, United States;2. Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Monseñor Alvaro del Portillo 12455, Las Condes, Santiago, Chile;3. Department of Civil Engineering, Universidad Andres Bello, Santiago 8320000, Chile;1. State Key Laboratory of Hydroscience and Engineering, Tsinghua Univ., Beijing, 100084, China;2. State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, 810016, China;3. Virginia Institute of Marine Science, College of William & Mary, Center for Coastal Resource Management, Gloucester Point, VA, 23062, USA;1. National Inland Waterway Regulation Engineering Research Center, Chongqing Jiaotong University, 66 Xuefu Road, Nan’an District, Chongqing 400074, China;2. Changjiang Chongqing Harbour and Waterway Engineering Investigation and Design Institute, Chongqing, China;1. Research Center for Oceanography, Indonesian Institute of Sciences, Jl. Pasir Putih 1, Ancol Timur, Jakarta, Indonesia;2. Jiaozhou Bay National Marine Ecosystem Research Station, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;3. Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;1. Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of mechanics, Chinese Academy of Sciences, Beijing 100190, China;2. Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China |
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| Abstract: | Many parameters are involved in the deposition of a known mass of sand particles discharge from oblique pipes used in a range of engineering applications. Existing knowledge is not sufficient to accurately predict sediment mound dimensions and development from vertical and horizontal pipes. To better understand deposition patterns, laboratory experiments were done to investigate the development of subaqueous sand deposits from oblique pipes in stagnant water. Factors including nozzle diameter, release angle, release height, and sand mass were evaluated. It was found that nozzle size plays the most important role in shape formation and mound development. Release angle and release height were secondarily important. Five different shape patterns were observed and denoted as circular, ellipse, circular-ring, ellipse-ring, and pear-shaped. The scour hole diameter in the middle of the sediment mound was predicted using engineering assumptions and available semi-empirical correlations from the literature. It was found that the existing formulations can accurately predict the size of the scour hole for large release angles (θ = 60°). An aspect ratio of L/do was defined to combine the effect of nozzle size, do, and sand mass where L is the equivalent length of sand particles in a pipe. It was found that the mass balance equation can predict the deposition for L/do < 100. For higher aspect ratios, semi-empirical formulations were developed to predict the deposition length, width, height, and area with ±10% error. |
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| Keywords: | Mound development Sediment deposition Sand jets Particle clouds Underwater mound |
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