The use of Direct Numerical Simulations for solving industrial flow problems

At the end of the last decade it was shown that predictions by means of Direct Numerical Simulations (DNS) agree well with experimental results obtained with Laser Doppler Anemometry and Particle Image Velocimetry (see for example Eggels et al. (

1994

)) if weakly turbulent flows, i.e. low Reynolds numbers, are considered. In spite of the widely accepted merit of DNS for fundamental flow studies until now the technique could not shake off the prejudice that it is of little use for solving industrial flow problems. The reason might be that the required computational resources increase with approximately the third power of the Reynolds number and most of the industrially relevant flows, and in particular aircraft or vehicle aerodynamics, are characterized by very high Reynolds numbers. In this regard Spalart (

1999

) estimated in the year 1999, that it will take until 2080 for DNS to be applicable to such flows. However, in the last years we performed a number DNS-studies which are relevant for various industrial branches. The common objective of these incompressible flow simulations was to produce a reliable and comprehensive flow data base for the validation and improvement of corresponding Reynolds-averaged Navier-Stokes simulations (RANS). The latter rely on turbulence models which are known to perform well for simple shear flows but not in general.