Effect of Pulsations on the Wake Structure of a Circular Cylinder
The effect of flow perturbations (sinusoidal pulsations) on the wake structure of a circular cylinder in turbulent crossflow has been studied by means of LDA measurements along the wake axis. The results show the variation of the extent of the recirculation bubble and vortex formation regions and the longitudinal distance of the vortices in the von Karman street with pulsation frequency and amplitude within the lock-on range.Copyright © 2002 by ASME
The purpose of this note is to document some work done as part of the effort directed at designing and simulating a bunch-by-bunch feedback system to control longitudinal coupled bunch instabilities in the B-factory. In particular, I discuss the ring model used in the simulation program developed to study this feedback system. Basically the simulation is a simple tracking program in which the rf drive voltage, the wakefields due to all the bunches, the synchrotron radiation losses, and the kicks applied to the bunches by the bunch-by-bunch feedback are all modelled as voltages applied at a single, discrete point in the ring. The computation of the bunch-by-bunch feedback voltages may of course be done by any desired algorithms. An example and discussion of the general behavior without bunch-by-bunch feedback is given at the end of this report.