不同底床粗糙对异重流运动特性的影响
Effects of Bottom Roughness on Gravity Cur-rent Motions
DOI: 10.12677/IJFD.2017.54016, PDF,    国家科技经费支持
作者: 胡可可：浙江省水利河口研究院，浙江 杭州；杨彧, 林颖典：浙江大学海洋学院，浙江 杭州
关键词: 异重流；底床粗糙度；Gravity Currents； Bottom Roughness
摘要: 本研究利用开闸式盐水异重流试验及数值模拟探讨在不同盐度及底床粗糙度的影响下对异重流运动特性的影响。实验利用粒子图像测速法(PIV)和摄像机可以记录整个异重流的运动过程，异重流头部的位置和速度是主要的研究区域。研究结果显示，底床铺设泥沙在异重流运动中扮演重要的角色，增加了底床摩阻，使头部的运动速度及涡度值明显降低，而且异重流头部变钝。利用重整化群(RNG)的k-ε湍流模式模拟研究异重流头部结构，发现数值结果和实验结果吻合良好，并可利用从剖面水平流速解释异重流加速区、等速区和减速区。当底床是光滑时，在两种流体的交介面有著因为卷吸作用所造成的负向速度，也就是异重流剖面水平速度产生剧烈变化；底床泥沙的存在改变了异重流的水平速度分布，使剖面流速并未出现负向流速。
Abstract: In this study, lock-exchange gravity current experiments and numerical models are used to investigate the effect of saline concentration and bottom roughness on gravity current dynamics. The Particle Image Velocimetry (PIV) system and a digital camcorder are employed to obtain the evolution of gravity currents on sediment beds. Spatial-temporal evolutions of the current speed, height and macro-structures of current head are analyzed. The results show that bottom sediments play an important role toward the current kinematics, particularly in decreasing the front velocity and vorticity, and changing the front shape. Using the Re-Normalization Group (RNG) k-ε turbulent model to simulate the gravity current motions can obtain good agreement with the experimental data. The simulated horizontal current velocity can be used to explain the acceleration, constant speed, and deceleration motions. At the interface between the two different fluids, a negative velocity can be observed due to the entrainment phenomena. Bed sediments change the horizontal velocity profiles of current, entrainment phenomena and inhibit the occurrence of the negative velocity in the horizontal direction. The velocity fluctuation becomes less pronounced on the sediment beds.
文章引用：胡可可, 杨彧, 林颖典. 不同底床粗糙对异重流运动特性的影响[J]. 流体动力学, 2017, 5(4): 141-150. https://doi.org/10.12677/IJFD.2017.54016

参考文献

[1] Alahyari, A.A. and Longmire, E.K. (1996) Development and Structure of a Gravity Current Head. Experiments in Fluids, 20, 410-416. [Google Scholar] [CrossRef] 
[2] Simpson, J.E. and Britter, R.E. (1979) The Dynamics of the Head of a Gravity Current Advancing over a Horizontal Surface. Journal of Fluid Mechanics, 94, 477-495. [Google Scholar] [CrossRef] 
[3] Huppert, H.E. and Simpson, J.E. (1980) The Slumping of Gravity Currents. Jour-nal of Fluid Mechanics, 99, 785-799. [Google Scholar] [CrossRef] 
[4] Hallworth, M.A., Phillips, J.C., Huppert, H.E., et al. (1993) Entrainment in Turbulent Gravity Currents. Nature, 362, 829-831. [Google Scholar] [CrossRef] 
[5] Britter, R.E. and Simpson, J.E. (1978) Experiments on the Dynamics of a Gravity Current Head. Journal of Fluid Mechanics, 88, 223-240. [Google Scholar] [CrossRef] 
[6] Rottman, J.W. and Simpson, J.E. (1983) Gravity Currents Produced by In-stantaneous Releases of a Heavy Fluid in a Rectangular Channel. Journal of Fluid Mechanics, 135, 95-110. [Google Scholar] [CrossRef] 
[7] Hacker, J., Linden, P.F. and Dalziel, S.B. (1996) Mixing in Lock-Release Gravity Currents. Dynamics of Atmospheres & Oceans, 24, 183-195. [Google Scholar] [CrossRef] 
[8] Adduce, C., Sciortino, G. and Proietti, S. (2012) Gravity Currents Produced by Lock Exchanges: Experiments and Simulations with a Two-Layer Shallow-Water Model with Entrainment. Journal of Hydraulic Engineering-ASCE, 138, 111-121. [Google Scholar] [CrossRef] 
[9] He, Z.G., Zhao, L., Lin, T., Hu, P., Lv, Y., Ho, H.C. and Lin, Y.T. (2016) Hydrodynamics of Gravity Currents down a Ramp in Linearly Stratified Environments. Journal of Hydraulic Engineer-ing-ASCE, 143, Article ID: 04016085. [Google Scholar] [CrossRef] 
[10] 彭明, 袁辉靖, 李存标. 开闸式异重流锋速转变的一个判据[J]. 中国科学: 物理学、力学、天文学, 2015, 45(3): 034702.
[11] Ezequiel, M.J. and García, M.H. (2009) Combined PIV/PLIF Meas-urements of a Steady Density Current Front. Experiments in Fluids, 46, 265-276. [Google Scholar] [CrossRef] 
[12] Nogueira, H., Adduce, C. and Franca, E. (2013) Analysis of Lock-Exchange Gravity Currents over Smooth and Rough Beds. Journal of Hydraulic Research, 51, 417-431. [Google Scholar] [CrossRef] 

为你推荐