Accession Number : AD0655150

Title :   RELATIVE MOTION AND COAGULATION OF PARTICLES IN A TURBULENT GAS,

Corporate Author : NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CALIF

Personal Author(s) : Huebsch,I. O.

Report Date : 04 MAY 1967

Pagination or Media Count : 112

Abstract : The existing theory of turbulent-accelerative coagulation applies only to particles so small that they respond to all fluid motions, including those of the smallest, most rapidly accelerating eddies (microscale eddies). The maximum particle diameter for which this theory applies is typically 5 to 10 microns. A review of coagulation and small-scale turbulence theory showed that the theory of turbulent-accelerative particle motion relative to the fluid and coagulation may be extended to particles whose relaxation times are greater than the period of microscale eddies. The extension is based on the concept that each such particle moves at a characteristic speed relative to the fluid, corresponding to the speed of the eddy size whose period equals the particle relaxation time. Thus for each particle size there is a 'resonant' eddy size. Different coagulation mechanisms were compared. Apparently the only situation in which turbulent-accelerative coagulation can be more important than gravitational coagulation, is in nuclear-explosion clouds. A method of numerical computation of coagulation due to all the mechanisms cited was developed. (Author)

Descriptors :   (*TURBULENCE, PARTICLES), GASES, MOTION, INTERACTIONS, EQUATIONS OF MOTION, THEORY, VELOCITY, SHEAR STRESSES, BROWNIAN MOTION, AEROSOLS

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE