Numerical study of flow control methods and splitting effects in a round submerged jet

The paper presents the results of numerical simulation of a submerged jet flowing from a circular hole in a wall with introduction of various types of perturbations. Active methods of flow control, including imposition of axial and helical harmonic oscillations on the inlet profile of the jet velocity, vibration of the jet nozzle, as well as their combinations, are considered. It is found that the external forcing leads to the effects of jet splitting at Reynolds number Re >= 1000 in wide ranges of perturbation frequencies and amplitudes, as it is shown in the studies of other authors. The mechanisms of interaction of vortex structures during jet bifurcation are investigated, and the angle of flow expansion in the bifurcation plane, which demonstrates an increase with a growing Re, is estimated. Calculations at 500 <= Re <1000 show that in order to obtain and enhance the above effects, it is necessary to optimize the forcing parameters, in particular, the type, frequency, and amplitude of perturbation. It is concluded that mechanical vibrations of the nozzle appear to be a more efficient way to control the flow than helical excitation of the inlet velocity profile.