Abstract
Vertical structure of decaying grid turbulence is studied using a salt-stratified water tank.The Particle Image Velocimetry(PIV) and the Laser Induced Fluorescence(LIF) are used to measure the time evolutions of the velocity field and the density field in a vertical section.It is found that both the vertical kinetic energy and the potential energy oscillate in opposite phase at half the buoyancy period.The vertical density flux oscillates at the same frequency,but the oscillation is about π/2 out of phase,suggesting that the flux transfers energy between the vertical kinetic energy and the potential energy.Time evolution of the velocity and density spectra shows that the vertical scale of turbulence gradually becomes smaller than the horizontal scale.
