Effect of Viscosity on Vibration-Induced Motion of a Spherical Particle Suspended in a Fluid Cell

Abstract

Production of protein and semi-conductor crystals with advanced quality and properties is possible under microgravity conditions due to the suppression of convection effects. However, aboard space platforms, g-jitter induced motions of solid particles can cause unsteady convection that may result in degradation of the properties of crystals produced. There are different effects of g-jitter on small particles suspended in a fluid cell which are not fully understood. To investigate these small vibration effects, ground experiments were conducted by suspending a spherical particle with a thin wire in a rectangular fluid cell and subjecting the cell and particle to horizontal vibrations with different frequencies and amplitudes. The fluid viscosity was varied to investigate the attraction or repulsion force induced in the direction normal to the direction of the vibration. The force was found to change from attraction to repulsion with an increase in the fluid viscosity and increase with the increasing vibration frequency and amplitude.

The patterning behaviour and accumulation of spherical particles in a vibrated non-isothermal liquid

“…The related mechanisms have been placed in a precise theoretical context over recent years, see, e.g., the excellent works by Thomson et al 22 , Ivanova et al 23 , Kozlov et al 24 , Hassan et al 25 , Hassan and Kawaji 26 , Saadatmand and Kawaji 27 . The major outcome of such theoretical efforts has been the derivation of precise mathematical expressions relating the interaction forces to the physical properties of the considered solid-liquid system over a wide spectrum of conditions (viscous or inviscid fluids, low or high frequencies, dilute or concentrated suspensions, etc.).…”

Attractive forces on hard and soft colloidal objects located close to the surface of an acoustic-thickness shear resonator

“…Steady forces between particles or bubbles and a tangentially vibrating surface were also reported in the context of experiments under conditions of microgravity [25][26][27]. Such forces initiate a convective flow, which may disturb the experiment (often crystallization).…”

“…While there clearly is a connection between this work and Refs. [25][26][27], our results should not be directly applied to the configuration discussed there.…”

On the nature, formation and diversity of particulate coherent structures in microgravity conditions and their relevance to materials science and problems of astrophysical interest

“…The related mechanisms have been placed in a precise theoretical context over recent years (the reader is referred to the excellent studies by Thomson et al (1997), Ivanova and Kozlov (2002); Kozlov et al (2006), Hassan and Kawaji (2008), Saadatmand and Kawaji (2010)). …”