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Collision rate of small particles in a homogeneous and isotropic turbulence
Author(s) -
Yuu Shinichi
Publication year - 1984
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690300515
Subject(s) - turbulence , relative velocity , isotropy , coalescence (physics) , mechanics , physics , collision , classical mechanics , collision frequency , homogeneous isotropic turbulence , particle (ecology) , reynolds number , optics , direct numerical simulation , ion , geology , oceanography , computer security , quantum mechanics , astrobiology , computer science
A theoretical equation is derived for the collision rate of aerosol particles in a homogeneous and isotropic turbulent system. This equation takes into account the relative velocity between fluid and particles. The calculated results indicate that the relative velocity between fluid and particles is the main factor in the turbulent coagulation (agglomeration, coalescence) of unequally sized particles in an air flow. This hold true, even when the particle sizes are less than 1 micron. For particles of equal radii the coagulation coefficient reaches its minimum value, because the effect of motion relative to the fluid now becomes zero and only the spatial variation of turbulent motion remains to cause collisions between the particles. For particles following a fluid motion completely, as in a water stream, the equation for the collision rate reduces to the Saffman and Turner equation.