Laboratory experiment on turbulent mixing and fractal dimension of a density interface in a stably stratified fluid

摘要

Laboratory mixing box experiments were undertaken to examine turbulent mixing and structure across a density interface in a stably stratified two component fluid (fresh on salt), subjected to shear-free turbulence induced by an oscillating grid within the salt water layer. The entrainment laws take the form of E = Ri_0 ~(-n) (11=312 or 7/4). This indicates that the rate of mixing deceases with decreasing turbulence intensity. Fractal dimension of the three-dimensional density interface is larger than 2. Fractal dimension decreases with an increasing overall Richardson number. This suggests that the density interface becomes smoother with decreasing turbulence intensity.