Accession Number : ADA192572

Title :   Numerical Experiments on Turbulent Mixing.

Descriptive Note : Final rept. Dec 84-Dec 87,

Corporate Author : CORNELL UNIV ITHACA NY

Personal Author(s) : Pope, Stephen B

PDF Url : ADA192572

Report Date : 02 Feb 1988

Pagination or Media Count : 7

Abstract : Mixing in simple turbulent flows has been investigating using 64 cubed and 128 cubed Direct Numerical Simulations. In turbulent combustion, mixing by molecular transport is an essential process that is not well understood. Because mixing occurs on the smallest length and time scales it is difficult to study experimentally. Instead, we have employed direct numerical simulation of turbulence, initially for a conserved passive scalar in homogeneous isotropic turbulence. The Eulerian velocity and scalar fields are calculated from the exact evolution equations, and both Eulerian and Lagrangian statistics are deduced from the computed fields. A particle-tracking scheme, needed to extract Lagrangian information, has been implemented. The testing of a number of such particle tracking schemes has been completed with good results: accurate Lagrangian information can be extracted at a modest computational cost. In order to study processes in stationary turbulence, a forcing algorithm has been implemented. Tests on this scheme are complete, again with good results: the small scales are unaffected by the details of the forcing. Studies have been performed of: the mixing of a passive scalar; Lagrangian velocity, Acceleration and dissipation statistics; and Mixing and combustion problems viewed in terms of surfaces.

Descriptors :   *COMBUSTION, *MIXING, *TURBULENT FLOW, ALGORITHMS, COMPUTATIONS, EQUATIONS, EVOLUTION(GENERAL), LAGRANGIAN FUNCTIONS, MATHEMATICAL MODELS, MOLECULAR PROPERTIES, NUMERICAL ANALYSIS, NUMERICAL METHODS AND PROCEDURES, PARTICLES, PASSIVE SYSTEMS, SCALAR FUNCTIONS, SCALE, STATIONARY, STATISTICS, TIME, TRACKING, TRANSPORT PROPERTIES, TURBULENCE, VELOCITY, ACCELERATION, DISSIPATION, SURFACES

Subject Categories : Fluid Mechanics
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE