Direct Numerical Simulation of Microparticle Motion in Channel Flow with Thermophoresis

The motion of microparticles in a vertical flow channel driven by drag and thermophoretic forces was simulated using the direct numerical simulation method with the particles tracked using the Lagrangian method. The particle motions were analyzed for five sizes of particles ( $d_p=1$ , 2.5, 10, 20, and $100\mu \mathrm{m}$ ) at three temperature differences ( $\Delta t=0$ , $130$ , and $180°\mathrm{C}$ ). The results showed that the effect of thermophoresis on the deposition near the wall decreases with increasing particle diameter and can be neglected for particles with $d_p=100\mu \mathrm{m}$ . Since the deposition rates of inhalable particles $\left({\mathrm{PM}}_{10}\right)$ increase dramatically as the thermophoresis force increases, especially for particles with $d_p=1\mu \mathrm{m}$ , thermophoresis is an effective method for collecting inhalable particles.