Direct numerical simulations of the Navier-Stokes alpha model

We explore the utility of the recently proposed alpha equations in providin g a subgrid model for fluid turbulence, Our principal results are compariso ns of direct numerical simulations of fluid turbulence using several values of the parameter alpha, including the Limiting case where the Navier-Stoke s equations are recovered. Our studies show that the large scale features, including statistics and structures, are preserved by the alpha models, eve n at coarser resolutions where the fine scales are nor fully resolved. We a lso describe the differences that appear in simulations. We provide a summa ry of the principal features of the alpha equations, and offer some explana tion of the effectiveness of these equations used as a subgrid model for th ree-dimensional fluid turbulence, (C) 1999 Elsevier Science B.V. All rights reserved.