Progress in direct numerical simulation of turbulent transport and its control

With continuous advances in large scale computers, numerical methods and post-processing environment, direct numerical simulation (DNS) has played an important role in various fundamental studies of turbulent transport and its sophisticated control. After general remarks on grid requirement and numerical techniques of DNS, its novelty is highlighted through its recent applications to a dynamically complex flow and a flow control problem. The DNS of a channel flow under coupled dynamical effects of buoyant and Coriolis forces reveals peculiar phenomena of momentum and heat transfer with the quasi-coherent structures being strikingly altered. In a trial simulation of the active turbulence control with a virtual damping force, the most effective spatio-temporal distribution of the control input is sought by adopting a suboptimal control theory. Future directions of DNS for turbulence transport research are also discussed. (C) 1998 Elsevier Science Inc. All rights reserved.