title: Observation of slip flow in thermophoresis.
abstract: Two differing theories aim to describe fluidic thermophoresis, the movement of particles along a temperature gradient. While thermodynamic approaches rely on local equilibrium, hydrodynamic descriptions assume a quasi-slip-flow boundary condition at the particle's surface. Evidence for slip flow is presented for the case of thermal gradients exceeding (aS_(T)(-1) with particle radius a and Soret coefficient S_(T). Thermophoretic slip flow at spheres near a surface attracts or repels tracer particles perpendicular to the thermal gradient. Moreover, particles mutually attract and form colloidal crystals. Fluid dynamic slip explains the latter quantitatively.
authors.affiliation: Systems Biophysics, Ludwig Maximilians Universität München, Amalienstrasse 54, Munich, Germany.
authors.forename: Franz M
authors.initials: FM
authors.lastname: Weinert
authors.forename: Dieter
authors.initials: D
authors.lastname: Braun
mesh_terms: D000465:Algorithms; D003460:Crystallization; D004247:DNA / Q000737:chemistry; D004563:Electrochemistry; D020342:Finite Element Analysis; D053758:Nanoparticles; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics
chemical_list: D011137:Polystyrenes; D004247:DNA