论文标题
湍流气溶胶中苛性形成的途径
Paths to caustic formation in turbulent aerosols
论文作者
论文摘要
湍流中较小但重，相同颗粒的动力学表现出奇异性，称为苛性遗传，导致空间粒子密度的波动很大，并且在碰撞速度中。对于大粒子，惯性粒子位置处的流体速度本质上是白噪声信号，苛性形成类似于kramers逃脱。在这里，我们表明，小颗粒惯性下的苛性形成是不同的。在粒子轨迹的附近形成苛性碱，这些粒子轨迹经历了特定的流体速度梯度病史，其特征是低涡度和超过较大阈值的剧烈应变。我们开发了一种理论，该理论用在小惯性极限下接近的苛性形成的最佳途径来解释我们的发现。
The dynamics of small, yet heavy, identical particles in turbulence exhibits singularities, called caustics, that lead to large fluctuations in the spatial particle-number density, and in collision velocities. For large particle, inertia the fluid velocity at the particle position is essentially a white-noise signal and caustic formation is analogous to Kramers escape. Here we show that caustic formation at small particle inertia is different. Caustics tend to form in the vicinity of particle trajectories that experience a specific history of fluid-velocity gradients, characterised by low vorticity and a violent strain exceeding a large threshold. We develop a theory that explains our findings in terms of an optimal path to caustic formation that is approached in the small inertia limit.
