A Theory of Turbulence in a Homogeneous Fluid Induced by an Oscillating Grid.

Abstract

Recent studies of turbulence indicate that the root-mean-square horizontal velocity sigma(u) is proportional to the oscillation frequency f and is inversely proportional to distance from the grid, and that the integral length scale l is proportional to this distance and independent of f. A theoretical model is based on the Navier-Stokes equations and the no-slip boundary condition but contains no other assumptions. The statistically steady behavior is as observed in the experiment. In the unsteady case, the front separating turbulent and non-turbulent fluid propagates at a speed inversely proportional to the square root of time. The problem has importance with respect to the mixed layer in the upper ocean or in the lower atmosphere. The present model does not consider buoyancy effects but if a passive contaminant is present the mean concentration is governed by the one-dimensional diffusion equation with constant turbulent coefficient of diffusion.

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Document Details

Document Type
Technical Report
Publication Date
Feb 01, 1977
Accession Number
ADA038424

Entities

People

  • Robert R. Long

Organizations

  • Johns Hopkins University

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Buoyancy
  • Diffusion
  • Environmental Pollutants
  • Equations
  • Fluid Dynamics
  • Fluid Mechanics
  • Frequency
  • Integrals
  • Materials
  • Materials Science
  • Mechanics
  • Military Research
  • Navier Stokes Equations
  • Physics Laboratories
  • Planetary Sciences
  • Reynolds Number
  • Turbulence

Fields of Study

  • Mathematics

Readers

  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.
  • Fluid Dynamics.