Determination of thermophoretic force on a particle in transitional flow

Both positive and negative thermophoretic forces are experimentally measured using a nano-Newton Thrust Stand (nNTS) to determine the effect of temperature gradient on force produced. It is found that there is an average 62% maximum force increase as thermally driven walls about a spherical particle are increased 300% in separation distance while thermal gradient is held constant. Negative thermophoretic force is found to increase at the same order of magnitude as positive thermophoretic force with increasing temperature gradient.