American Institute of Aeronautics and Astronautics 1 Three Dimensional Active Flow Control Drag Reduction Studies Over a Bluff Body Using a Coupled Lattice Boltzmann-Navier-Stokes Methodology Nandita Yeshala 1 and Lakshmi N. Sankar 2 School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332-0150 A coupled Lattice Boltzmann – Navier-Stokes methodology in three dimensions is implemented for modeling flow control phenomena. A one cell overlap between the Lattice Boltzmann (LB) and Navier-Stokes (NS) grids is used to exchange information between the two solvers. Flow over a circular cylinder has been chosen as the case study for the present drag reduction studies. A comparison of the baseline flow over a two-dimensional and three- dimensional cylinder has been performed. The difference in the flow phenomena between the two cases has been examined. The coupled methodology has subsequently been applied to the flow over a 3-D circular cylinder with a synthetic jet device for drag reduction. The LB solver is used to resolve the flow physics at the small length scales in the synthetic jet region and the NS solver is used to model the rest of the flow domain. A drag reduction of 8.5 percent is observed in the synthetic jet case compared to the baseline case without active flow control. Nomenclature C p = pressure coefficient c s = speed of sound in lattice units l = length N = characteristic length in lattice units p = pressure of the fluid Re = Reynolds number t = time u = streamwise velocity v = cross-stream velocity x = position vector Δt,δt = time step Δx,δx = spatial step ρ = density of the fluid τ = single time relaxation parameter υ = kinematic viscosity in lattice units d = subscript denotes dimensionless units j = subscript denotes values near jet slot lb = subscript denotes lattice units o = subscript denotes reference value p = subscript denotes physical units 1 Graduate Research Assistant, School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Dr, Atlanta, Georgia 30332-0150, Student Member, AIAA. 2 Regents Professor and Associate Chair for Undergraduate Programs, School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Dr, Atlanta, Georgia 30332-0150, Fellow, AIAA. 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 4 - 7 January 2011, Orlando, Florida AIAA 2011-467 Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Downloaded by GEORGIA INST OF TECHNOLOGY on November 5, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.2011-467