The influence of surfactants on thermocapillary flow instabilities in low Prandtl melting pools

摘要: Flows in low Prandtl number liquid pools are relevant for various technical applications and have so far only been investigated the case of pure fluids, i.e., with a constant, negative surface tension temperature coefficient ∂γ/∂T. Real-world fluids containing surfactants dependent ∂γ/∂T > 0, which may change sign to < 0 at critical Tc. Where thermocapillary forces main driving force, this can tremendous effect on resulting flow patterns associated heat transfer. Here we investigate stability such flows five Marangoni numbers range 2.1 × 106 ≤ Ma 3.4 107 using dynamic large eddy simulations, validate against high resolution direct numerical simulation. We find that cases span all regimes, stable laminar 106, transitional rotational instabilities = 2.8 4.6 turbulent 1.8 107.