This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV...This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.展开更多
Nanomaterials(NMs)have become an integral part of our daily life,and their extensive production will only increase with the increasing time.These NMs exhibit significant contrast regarding dimension,reaction,and struc...Nanomaterials(NMs)have become an integral part of our daily life,and their extensive production will only increase with the increasing time.These NMs exhibit significant contrast regarding dimension,reaction,and structure.The most important aspect of the NMs is that these can be easily manipulated and engineered to custom-suit different functions/industries.Owing to their dynamic nature,these NMs behave differently when introduced in any medium.In soil,the behavior of NMs is significantly controlled by the interactions of nanomaterials with soil phases.Although NMs are deemed beneficial for human-use,yet these also carry lethal effects.Moreover,there is a dearth of adequate research for the interactions among nanomaterials and soil physicochemical properties;their accumulation-dissolution dynamics in soil-plant systems;and their long term influence on soil health.Several NMs induce physiological stress when introduced inside the body.Thus,various researchers have devised green pathways for producing NMs,although their wide applicability is still questionable.Although the domain of nanotechnology is greatly explored,yet there remain several grey areas which need to be addressed for sustainable utilization of these unique materials in the benefit of humankind.展开更多
文摘This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.
文摘Nanomaterials(NMs)have become an integral part of our daily life,and their extensive production will only increase with the increasing time.These NMs exhibit significant contrast regarding dimension,reaction,and structure.The most important aspect of the NMs is that these can be easily manipulated and engineered to custom-suit different functions/industries.Owing to their dynamic nature,these NMs behave differently when introduced in any medium.In soil,the behavior of NMs is significantly controlled by the interactions of nanomaterials with soil phases.Although NMs are deemed beneficial for human-use,yet these also carry lethal effects.Moreover,there is a dearth of adequate research for the interactions among nanomaterials and soil physicochemical properties;their accumulation-dissolution dynamics in soil-plant systems;and their long term influence on soil health.Several NMs induce physiological stress when introduced inside the body.Thus,various researchers have devised green pathways for producing NMs,although their wide applicability is still questionable.Although the domain of nanotechnology is greatly explored,yet there remain several grey areas which need to be addressed for sustainable utilization of these unique materials in the benefit of humankind.
