Lorenceau Elise, Restagno Frédéric, Quéré David
Physique de la Matière Condensée, UMR 7125 du CNRS, Collège de France, 75231 Paris Cedex 05, France.
Phys Rev Lett. 2003 May 9;90(18):184501. doi: 10.1103/PhysRevLett.90.184501. Epub 2003 May 8.
When a viscous liquid hits a pool of liquid of the same nature, the impact region is hollowed by the shock. Its bottom becomes extremely sharp if increasing the impact velocity, and we report that the curvature at that place increases exponentially with the flow velocity, in agreement with a theory by Jeong and Moffatt. Such a law defines a characteristic velocity for the collapse of the tip, which explains both the cusplike shape of this region, and the instability of the cusp if increasing (slightly) the impact velocity. Then, a film of the upper phase is entrained inside the pool. We characterize the critical velocity of entrainment of this phase and compare our results with recent predictions by Eggers.
当一种粘性液体撞击到性质相同的液体池时，冲击区域会因撞击而凹陷。如果提高撞击速度，其底部会变得极其尖锐，并且我们报告称该位置的曲率会随着流速呈指数增长，这与Jeong和Moffatt的理论一致。这样的规律定义了尖端坍塌的特征速度，这既解释了该区域的尖状形状，也解释了如果（略微）提高撞击速度时尖端的不稳定性。然后，上层液体的一层薄膜会被卷入液体池中。我们表征了该相卷入的临界速度，并将我们的结果与Eggers最近的预测进行了比较。
