NUMERICAL STUDY OF A DESCENDING SPHERE IN A LOW REYNOLDS NUMBER STRONGLY STRATIFIED FLUID

The flow generated by a sphere descending uniformly in a linea rly stratified diffusive fluid is inves- tigated numerically for different Reynolds (Re) and Froude (F ) numbers. The parameters used for the simulations were 10 1 � Re � 10 and 10 2 � F � 10 2 , keeping the Schmidt number, Sc (= 700, typical of sea water) fixed. The results demonstrate drag dependence on viscosity and stratification, suggesting that changes in these parameters would be intimately related to the phenomena of zooplankton vertical movement in the ocean.