Fluid/Solid Boundary Conditions in Non-Isothermal Systems

The existing theoretical research concerned with thermal creep at fluid/solid interfaces is briefly reviewed, and the importance of microgravity-based experimental data is then discussed. It is noted that the ultimate goal of this research is a rational molecular level theory that predicts the dependence of a dimensionless thermal creep coefficient, Ctc, on relevant dimensionless parameters describing the way fluid molecules interact with the solid surface and how they interact among themselves. The discussion covers thermophoresis of isolated solid spheres and aggregates in gases; solid sphere thermophoresis in liquids and dense vapors; thermophoresis of small immiscible liquid droplets; and applications of the direct simulation Monte Carlo method.