DIRECT NUMERICAL-SIMULATION - A TOOL IN TURBULENCE RESEARCH

We review the direct numerical simulation (DNS) of turbulent hows. We stress that DNS is a research tool, and not a brute-force solution to the Navier-Stokes equations for engineering problems. The wide range o f scales in turbulent flows requires that care be taken in their numer ical solution. We discuss related numerical issues such as boundary co nditions and spatial and temporal discretization. Significant insight into turbulence physics has been gained from DNS of certain idealized flows that cannot be easily attained in the laboratory. We discuss som e examples. Further, we illustrate the complementary nature of experim ents and computations in turbulence research. Examples are provided wh ere DNS data has been used to evaluate measurement accuracy. Finally, we consider how DNS has impacted turbulence modeling and provided furt her insight into the structure of turbulent boundary layers.