An Experimental Study of Turbulent Convection in Air Using PIV Technique

Airside turbulent flow structure in a coupled air-water system has been investigated during natural convection. Two-dimensional velocity field in a plane perpendicular to the surface was measured using particle image velocimetry (PIV). The results show the presence of different flow regimes in turbulent velocity fields which increase the complexity of the phenomena. The spectral analysis shows the existence of two power law regimes in the wavenumber spectra of the horizontal and vertical turbulent velocities. The regime at lower wavenumbers exhibits slopes of −3 which correspond to the buoyancy subrange where the energy loss is due to the work against buoyancy. At relatively higher wavenumbers, the inertial subrange with slopes of −5/3 is manifested. The trends of the wavenumber spectra in the present study are similar to the kinetic energy spectra observed in the geophysical studies over land and oceans, which indicates that laboratory experiments could be used to understand the near-surface dynamics in the lower atmosphere.