An extended kernel for acoustic agglomeration simulation based on the acoustic wake effect

A new kernel is presented for the simulation of acoustic agglomeration processes, employing two different agglomeration mechanisms: the classical orthokinetic particle interaction, and an effect based on hydrodynamic particle attraction in Oseen flow fields, termed the acoustic wake effect. Acoustic wake particle interaction has recently found strong experimental confirmation in visualization studies which illustrated agglomerations of this type, especially between similarly and equally sized particles. The new agglomeration kernel is outlined as an extension of the classical orthokinetic expression by defining ''external'' refill volumes, in order to determine the refill factor for the ''inner'' (or orthokinetic) agglomeration volume. The resulting formulation allows the versatile implementation of arbitrary particle interaction effects into the orthokinetic agglomeration model. As an example, Dianov et al.'s one-dimensional particle interaction model for Oseen flow conditions is paired with the orthokinetic kernel to simulate acoustic wake particle capture. Even though Dianov et al.'s approach suffers from drastic limitations, it can be employed to draw some general conclusions about the effects of acoustic wake interaction on the dynamics of an aerosol. The new acoustic wake kernel reveals enhanced agglomeration between equally and similarly sized particles, and reduced activity between particles of very different size. This result resembles the behavior of aerosols in various acoustic agglomeration experiments documented in the literature. (C) 1997 Elsevier Science Ltd.