Experimental study of turbulent wake behind a diver

Experiments were done at the Davidson Laboratory, Stevens Institute of Technology in New Jersey. We used hot-film anemometer (TSI Model 1210-60W) to measure water velocity fluctuation generated by a diver. To provide proper tool to calculate turbulent kinetic energy s2U in the diver's wake, we extended Novikov's turbulent spectral theory to the large scale of motion which is much greater than the viscous energy dissipating scales and developed theoretical derivation of the energy spectral curve. This curve fitted very well to the data measured by numerous researchers. We estimated turbulent energy dissipation rate epsilon using Kolmogrov's quasi-equilibrium theory and calculated turbulent kinetic energy s2U using the universal curve. For the results, we have found that the curve was in good agreement with the measured turbulent energy spectra of the diver's wake. The turbulent kinetic energy s2U (m2/s2) and energy dissipation rate epsilon (m 2/s3) of diver's wake were in the range of 1.62 x 10-5 ≤ s2U ≤ 37.05 x 10-5, 1.2 x 10 -6 ≤ epsilon ≤ 67.7 x 10-6 , respectively and these values were well above the ambient levels. The characteristic length lambda (m) of diver's wake was in the range of 0.08 ≤ lambda ≤ 0.98 ∼ 1.98. s2U was inversely proportional to the diver's distance L d, and epsilon was proportional to Ld-2.