Atomization caused by the collision of a liquid-filled flask

One method of atomization involves utilizing the Faraday instability, which arises when a liquid is vibrated vertically. However, it is generally not easy to vibrate the entire liquid, especially at high frequencies. Here, we demonstrate that dropping a flask partially filled with liquid onto a solid surface can induce ~2 kHz vibrations and atomization at the gas–liquid interface. The impact occurs only once, with no noticeable vibration of the container afterward. Using a Kjeldahl flask with its bottom kept filled, we varied the liquid height in the neck. Atomization intensity changed non-monotonically with liquid height in the neck: none at 0 mm, strongest at 10 mm, suppressed at 70 mm, and reappearing at 80 mm. The observed vibration frequencies cannot be explained by a simple 1D pressure wave reflection model with sound velocity. We instead propose a model where pressure rise at the bottom excites vibration of the neck liquid column. This model reproduces the observed frequencies for both Kjeldahl and round-bottom flasks with different geometries. The model shows that increased fill height amplifies vibration but lowers its frequency. Their competition may determine atomization strength. Direct numerical simulations using a hybrid front-tracking/level set method was also conducted to verify this model.