77 research outputs found
Boundary Effects on Diffusiophoresis and Electrophoresis: Motion of a Colloidal Sphere Normal to a Plane Wall
Boundary Effects on Diffusiophoresis of Cylindrical Particles in Nonelectrolyte Gradients
Sedimentation Velocity and Potential in a Dilute Suspension of Charged Composite Spheres
Thermophoresis of an arbitrary three-dimensional array of N interacting arbitrary spheres
THERMOPHORESIS OF AN ARBITRARY THREE-DIMENSIONAL ARRAY OF N INTERACTING ARBITRARY SPHERES
A boundary-collocation technique, used earlier by Chen and Keh [(1996) Aerosol Sci.
Technol. 24, 21-35] in the study of the thermophoresis of N coaxial spheres along the line of their
centers, is extended to describe the motion of an assemblage of N aerosol spheres arranged
arbitrarily in three-dimensional space. The spheres are allowed to differ in radius, in thermal
conductivity and in surface properties; they may move independently, or they may be linked by
infinitesimally thin rods to form a rigid aggregate. The Knudsen numbers are assumed to be small so
that the fluid flow is described by a continuum model with a thermal creep and a hydrodynamic slip
at the particle surfaces.
Results are presented in terms of pair-interaction coefficients for the thermophoretic velocities of
the particles. For two-sphere systems• the translational and angular velocities of the particles at all
orientations and separation distances agree very well with the exact solutions obtained by using
spherical bipolar coordinates or the asymptotic solutions obtained by using a method of reflections.
The particle-interaction parameters of linear chains of three spheres show that the existence of the
third sphere can significantly affect the mobilities of the other two spheres, For the cases of a
rigid dumbbell composed of two spheres, the numerical solutions for the particle velocities compare
quite favorably with the formulas derived analytically. Finally, our numerical results for the
interaction between two spheres are used to find the effect of volume fractions of particles of each
type on the mean thermophoretic velocities in a polydisperse aerosol
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