Concussions and hydrodynamic origins of injuries

In many sports (combat, team or speed sports), Traumatic Brain Injury (TBI) has become a major healthcare problem, particularly because it is difficult to properly diagnose. The occurrence of TBI is generally defined by symptoms observed by doctors or empirical criteria related to the acceleration and the duration of the shock undergone by the head. In this work, we investigate hydrodynamics possible origins of destroying mechanisms causing concussions. One of the possible causes of TBI is the formation of cavitation bubbles in the cerebro-spinal fluid (CSF). To investigate the link between TBI and cavitation bubbles, we built a model experiment to induce cavitation bubbles through an impact. A tank, filled with water and hermetically closed with a flexible membrane is impacted on a damper, designed to vary acceleration and contact time. The formation and dynamics of cavitation bubbles is observed and studied inside the tank. Modeling those confined cavitation bubbles induced by a shock in the model experiment allows us to compute their damaging capacities and finally make a link to the real fields and conclude on the dangerousness of shocks received by athletes.