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# Accession Number:

## ADA038424

# Title:

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

# Descriptive Note:

## Technical rept.,

# Corporate Author:

## JOHNS HOPKINS UNIV BALTIMORE MD

# Report Date:

## 1977-02-01

# Pagination or Media Count:

##
12.0

# Abstract:

## Recent studies of turbulence indicate that the root-mean-square horizontal velocity sigmau 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.

# Distribution Statement:

## APPROVED FOR PUBLIC RELEASE

#