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ACCELERATING STATIONARITY IN LINEARLY FORCED ISOTROPIC TURBULENCE

Evangelos E. Akylas
Department of Civil Engineering and Geomatics, Cyprus University of Technology, P.O. Box 50329, 3603, Limassol, Cyprus

Stavros C. Kassinos
Department of Mechanical Engineering Stanford University Stanford, California 94305 USA; Department of Mechanical and Manufacturing Engineering, Computational Sciences Laboratory, UCY-COMPSCI University of Cyprus, Nicosia, Cyprus

Damian W. I. Rouson
Sandia National Laboratories, Livermore, CA 94550, United States

Xiaofeng Xu
General Motors Corporation, 823 Joslyn Avenue, Pontiac, MI 48340, United States

Abstract

The physics of the linear forcing of isotropic turbulence allows for some useful estimates of the characteristic length scales of the turbulence produced during the statistically stationary phase. With such estimates we could practically define uniquely the stationary statistics by means of the box-size of the simulation, the linear forcing parameter and the viscosity of each case. We try to explain the estimates and we use them in order to pre-describe the resulting statistically stationary energy spectra, retrieving well documented analytical spectral relations. The produced spectra are in very good agreement with the numerically calculated average spectra during the statistically stationary phase, for a variety of values of the dimensionless linear forcing parameter. The analytical forms are used as a revised initial condition for the production of isotropic turbulence which accelerates remarkably the achievement of stationarity, minimizing any transient phase and could be generalized for the initialization of several different cases.