Hydrodynamic instability of nanofluids in round jet for small Stokes number

摘要

The flow instability of particle-laden jet has been widely studied for large Stokes numbers. However, there is little attention on the case with small Stoke number, which often occurs in practical applications with nanoparticle-laden fluid. In this paper, the instability of nanofluids in round jet is studied numerically for St <= 0.01. The results show that the law of nanofluids instability is quite similar to regular particle instability for axisymmetric azimuthal mode n = 0. However, for asymmetric azimuthal mode n = 1, the regular pattern of instability is quite complex and different compared to common particle instability. The variations of wave amplification with wave number for different jet parameter B, Reynolds number Re, particle mass loading Z, Knudsen number Kn, Stokes number St and the azimuthal modes n are given. The flow usually gets more unstable as Knudsen number Kn increases, but the varying law gets inverse at high Reynolds number and at n = 1. The flow gets more unstable as Stokes number St increases at n = 0 but gets more stable at n = 1. The decreases in wave number stimulate the flow instability at n = 1 which shows distinct difference for the case at n = 0. Some unusual results of the effect of B, Re, Z on the flow instability are also discussed.