Theoretical and numerical study of acoustic coagulation of suspended particles
Date Issued
2002-07-31
Date
2002-07-31
Author(s)
DOI
902212E002199
Abstract
This project studies numerically the coagulation of small particles in a two-phase suspension flow. Three topics have been completed in the present project. (1) We have validated our calculations by comparing with different previous experiments using the orthokinetic interaction model for the collision frequency function. It is found that a relative low value of collision efficiency factor (about 0.2 – 0.4, depending on different parameters) is required for a correct numerical prediction. (2) For the coagulation of sub-micron particles, we have studied in details the relative importance of the Brownian coagulation and the acoustic coagulation. The effect of the Brownian coagulation increases as the size of the particle increases, but is opposite for the acoustic coagulation. For general cases, it is found that the acoustic effect can aid the coagulation when the diameter of the particle exceeds 50 nm. (3) We have carried out simulation of acoustic coagulation using the orthokinetic interaction model, the hydrodynamic interaction model, and the acoustic wake model (a combination of orthokinetic and hydrodynamic model). It is found that only the simulation with orthokinetic interaction model can preserve the mass of particles during the calculation. The items (1) and (3) stated above indicate that both the theory of the collision frequency function and the numerical method require further investigation, and will be studied in the second year.
Subjects
coagulation of small particles
sub-micron particles
sound wave
Brownain diffusion
mass conservation
Publisher
臺北市：國立臺灣大學應用力學研究所
Type
report
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