Computational modeling of synthetic jets

This thesis presents a CFD model that employs a novel moving grid methodology to investigate the interaction of an isolated synthetic jet in a crossflow. The current moving grid methodology is said to be 'novel' in the sense of formulation of equations in strong conservative form on a general, nonorthogonal grid system with moving boundaries. In addition, it also conserves space. This moving grid methodology can be easily extended and applied to other problems involving moving boundaries in the system. In the current study, numerical simulation was performed to investigate a timedependent behavior of a simplified configuration, which includes a two-dimensional, single synthetic jet interaction with a turbulent boundary layer. A simple, uniform, nonstaggered Cartesian grid of 270x74 was used. To employ an unsteady boundary condition, a moving diaphragm was introduced to a side wall of the cavity. Unsteady, Reynolds-Averaged, Navier-Stokes equations were solved numerically by a finitevolume method and applied to study the flow. The two-dimensional computational fluid code, HEAD2D was equipped with the standard k-e model. Programs were developed in Fortran. Ensight® was used to visualize the flow patterns.

The current study focuses on phase averaged velocity fields, which allows one to study the evolution of the synthetic jet essentially as a function of time. Results on several phase-averaged velocity profiles obtained with this novel moving grid methodology considerably agree with the trend of data obtained from experimental setup by NASA Langley Research Center [13].