论文标题
两层热驱动的湍流：接口破裂的机制
Two-layer Thermally Driven Turbulence: Mechanisms for Interface Breakup
论文作者
论文摘要
通常认为，湍流中滴或气泡的分解标准受表面张力和惯性的控制。但是，{\ it {buoyancy}}也可以在分手中发挥重要作用。为了更好地理解这一角色，我们在这里数字研究了两个不混溶的流体层的雷利 - 纳德对流，以确定浮力对界面分裂的影响。我们探讨了由Weber Number跨越的参数空间$ 5 \ leq我们\ Leq 5000 $（惯性与表面张力的比率）和两个流体之间的密度比$ 0.001 \leqλ\ leq 1 $，以固定的雷利（固定rayleigh）数量$ ra = 10^8 $ ra = 10^8 $ and prandtl $ $ $ $ $ pr = 1 $。在低$ WE $时，界面由于羽流而起伏。当$我们$大于临界值时，接口最终会分解。根据$λ$的不同，观察到两种分解类型：第一种类型发生在小$λ\ ll 1 $（例如空气水系统）时，当局部丝状厚度超过Hinze长度尺度时。第二种，非常不同的类型发生在大$λ$上，大约$ 0.5 <λ\ le 1 $（例如，油水系统）：这些层经历了浮力压倒性表面张力引起的周期性颠覆。对于两种类型，分手标准可以从力量平衡参数中得出，并与数值结果表现出良好的一致性。
It is commonly accepted that the breakup criteria of drops or bubbles in turbulence is governed by surface tension and inertia. However, also {\it{buoyancy}} can play an important role at breakup. In order to better understand this role, here we numerically study Rayleigh-Bénard convection for two immiscible fluid layers, in order to identify the effects of buoyancy on interface breakup. We explore the parameter space spanned by the Weber number $5\leq We \leq 5000$ (the ratio of inertia to surface tension) and the density ratio between the two fluids $0.001 \leq Λ\leq 1$, at fixed Rayleigh number $Ra=10^8$ and Prandtl number $Pr=1$. At low $We$, the interface undulates due to plumes. When $We$ is larger than a critical value, the interface eventually breaks up. Depending on $Λ$, two breakup types are observed: The first type occurs at small $Λ\ll 1$ (e.g. air-water systems) when local filament thicknesses exceed the Hinze length scale. The second, strikingly different, type occurs at large $Λ$ with roughly $0.5 < Λ\le 1$ (e.g. oil-water systems): The layers undergo a periodic overturning caused by buoyancy overwhelming surface tension. For both types the breakup criteria can be derived from force balance arguments and show good agreement with the numerical results.
