In this note we examine fluid violent kinematics in a plunging breaker. The fluid motion is computed in the frame of the potential flow theory. The fluid kinematics is basically generated by forcing the motion of a rectangular tank, starting from rest. When a sufficient level of energy is injected in the fluid, the free surface has highly nonlinear behavior, here a plunging breaker. In the vicinity of the main tip crest, a sharp corner (cusp) appears along the surface of the barrel. The appearance of this critical jet is described and discussed in terms of the spatial and temporal variations of the pressure field. In the present case a local pressure maximum is captured that follows a continuous decreasing pressure gradient in a region of positive Gaussian curvature of the pressure. It is also shown that, at the free surface before the appearance of the critical jet, there is a strong correlation between the change of sign of the Gaussian curvature of the pressure on the one hand and the radius of curvature of the free surface profile on the other hand.

在本文中，我们研究了破碎锤中的流体暴力运动学。在势流理论的框架内计算流体运动。从静止开始，流体运动学基本上是通过迫使矩形油箱运动而产生的。当在流体中注入足够水平的能量时，自由表面具有高度非线性的行为，此处是一个突然下降的断路器。在主尖端波峰附近，沿着发条盒表面出现一个尖锐的角（尖点）。根据压力场的空间和时间变化来描述和讨论该临界射流的外观。在当前情况下，捕获局部最大压力，该局部最大压力在压力的正高斯曲率区域中遵循连续减小的压力梯度。还表明，