| he evolving turbulent flow field, from start-up to steady state, in a cylindrical tank due to the rotation of a bluff body has been experimentally investigated. The investigation employed flow visualization, hydrodynamic torque measurements, and a nonintrusive measurement technique for obtaining fluid velocity. Experiments were conducted in two flow facilities differing in volume by a factor of 100 and with bluff bodies of different characteristic length L. Experiments were conducted over a Reynolds number ;For a given bluff body, decay begins at the same number of revolutions regardless of the rotation and acceleration rates provided the ratio ;The effects of angular acceleration, body geometry, tank geometry, and fluid level on the transient process and decay exponent are quantified, and a brief discussion of three-dimensional effects is presented. The significance of these results to the application of rapid crystal growth is discussed.;At start-up a vortex was shed from each of the bluff body corners. The strength of this vortex was shown to be proportional to the Reynolds number. For all cases investigated, three temporal regimes were observed to exist in the transient flow field. These regimes are (1) a build-up regime characterized by a constant value of the turbulent intensity,... |
