Stably stratified turbulent flows are common in the ocean and the atmosphere. Buoyancy forces in these flows tend to damp the vertical components of turbulence, altering the decay of turbulence. These studies encompassed experimental measurements of turbulence in airflow which had varying levels of thermal stratification. In addition to the fundamental study of turbulence decay in stratified flow, a thermally stratified wind tunnel was designed, and hot and cold wire instrumentation was developed for use in highly non-isothermal turbulence. This research was performed in the Department of Applied Mechanics and Engineering Science at UC San Diego.

Measured decay of vertical turbulent heat flux in strongly stratified grid turbulence. Brunt-Väisälä frequencies N ranging from 1.16 to 2.42 s^-1, Pr = 0.7.

Publications

J.H. Lienhard V and C.W. Van Atta, “The decay of turbulence in thermally stratified flow,” Journal of Fluid Mechanics, Vol. 210, Jan. 1990, pp.57-112. (PDF file) (doi)

J.H. Lienhard V and C.W. Van Atta, “Thermally stratifying a wind tunnel for buoyancy induced flows,” Experiments in Fluids, Vol. 7, No. 8, 1989, pp.542-546. (PDF file)

J.H. Lienhard V and K.N. Helland, “An experimental analysis of fluctuating temperature measurements using hot-wires at different overheats,” Experiments in Fluids, Vol. 7, No. 4, Jan. 1989, pp.265-270. (PDF file)

J. Haugdahl and J.H. Lienhard V, “A low-cost, high-performance DC cold-wire bridge,” J. Phys. E: Sci. Instr., Vol. 21, 1988, pp.167-170. (PDF file)