Direct Numerical Simulation on Turbulent Transportation and Thermophoretic Deposition of Micron-Sized Particles in Rectangle Channel

Abstract

The turbulent transportation and thermophoretic deposition of micron-sized particles ranging from 1-20 μm are studied by direct numerical simulation of a horizontal turbulent rectangular channel flow in this paper. Present research on thermophoretic deposition mainly focused on the sub-micron particles, whereas the particle size usually exceeds this range during radioaerosol monitoring. If a coolant leakage takes place in the primary loop, there will be a huge temperature gradient between the air and the wall, which leads to thermophoretic deposition. A temperature gradient of 1700 K/m is set between the hot and cold walls. Simulation results show that thermophoresis plays an important role in aerosol deposition which depends on particle size. It is found that deposition of 1 μm particles on the cold wall is almost 15 times more than that on the hot wall. With the increasing of particle size, the difference of thermophoretic deposition between the two walls decreases. In this paper, 10% particles per second are deposited by thermophoresis, which concludes that thermophoretic deposition should be considered and adjusted according to particle size during aerosol transportation where large temperature gradient exists.