Characteristics of density current dynamics over rough channel beds

摘要: Density currents occur in a variety of natural and man-made scenarios, this emphasises the importance studying them. The density-driven are main agent for sediment transportation many dam reservoirs. In most cases, these flow over surfaces which not smooth; nevertheless, effect bottom roughness on body has been fully understood. Hence, study mainly aims to examine structure density propagating rough beds. To achieve this, alterations velocity concentration profiles presence different configurations investigated. influence various entrainment ambient fluid into is also quantified. Initially, laboratory experiments were carried out with flowing smooth surface analyse dynamics range experimental conditions; provided baseline comparison. Then, seven bed (λ/Kr=1, 4, 8, 16, 32, 64 128 where λ denotes downstream spacing between each two subsequent elements Kr height) chosen encompass both dense sparse roughness. beds consisted square cross-section beams cover full channel width perpendicular direction repeated array. primary results research reveal that causes deceleration currents, reduction their excess densities enhancement water A critical (λ/Kr=8) found demonstrate lowest velocities. For spacings more than value, controlling reduced, velocities increased by expanding cavities elements. λ/Kr=128 very little maintained resembling those bed. magnitude rates varies depending substantial rate occurring λ/Kr=8, 5.26 times higher plane surface. Using dimensional analysis, equations proposed estimating mean findings contribute towards better parameterisation improved knowledge non-plane surfaces. This can lead prediction evolution practical cases as well planning design measures related control such currents.