Direct Numerical Simulation of Free Jet Under the Rotational Control

In recent past, a wide variety of applications have been found for the use jets in fields of study of flow control and many researchers have worked on jet flow control to enhance mixing and/or reduce noise. In order to develop a new mixing procedure, a direct numerical simulation (DNS) of dynamic controlled free jets was conducted. To achieve a high accurate computation, space discretisation method was performed using the hybrid scheme consisting sine or cosine series and 6th order compact scheme. The dynamic control proposed here are single and multiple rotating jets which are rotated unidirectionally around streamwise direction. According to the instantaneous vortex structures and, it is found that the flow pattern changes considerably with the rotating frequency. From the contour of streamwise velocity, in both cases, it is clear that the radial jet expansion of controlled jets are significantly enhanced compared to the uncontrolled one. We also concluded that, using the statistical entropy and the entrainment rate, it is clear that the mixing performance is significantly improved compared to the uncontrolled jet and under the same rotating frequency, the mixing performance of single rotating jet control is superior than multiple one.