How does the rip entry let Olympic divers reduce their splash?
📍 The George Washington University, Washington, DC
Competitive divers are able to achieve higher scores when they enter the water and create little to no splash and to do so they typically perform a rip entry. The rip entry is performed by impacting the water with their hands held flat before turning their body in a somersault.
In this way they are rapidly changing from a slender body to a bluff body underwater as well as rapidly decelerating. I investigated this with experiments and simulations, summaries of this work can be found below.
Featured in: Science News and This Week Junior
Experiments
I designed single jointed diver models and a driven entry body experimental setup to understand how a body that dynamically changes shape after impact changes the formation of the air cavity and splash.
Publications:
- Elizabeth Gregorio, Elias Balaras, and Megan C. Leftwich. “Air cavity deformation by single jointed diver model entry bodies.” Experiments in Fluids 64.11 (2023): 168. ⟨hal-04875637⟩https://hal.science/hal-04875637v1
- Elizabeth Gregorio, Iftakhar Alam, Elias Balaras, Megan C Leftwich. Dynamically Deforming Single Jointed Diver Models Reduce Pinch off Depth. 2025. (Pre-print) ⟨hal-04876578⟩ https://hal.science/hal-04876578v1
Simulations
I worked on code development to run simulations with the goal to reproduce my experimental results and investigate other diving questions. The code base is called Flash4 and is a direct navier stokes solver, I advanced the immersed boundary method force formulation for multiphase flows.
Projects:
- Cliff diving: Platform divers that are jumping from heights above 14m face a unique risk, they must activate their muscles to be able to safely enter the water. Still, cliff divers report neck pain and experiments point to the cause being the pinch off of the air cavity. I ran simulations with a human mesh with the goal of investigating this and other possible causes. This work was presented in a Gallery of Fluid Motion poster in 2022 (see left).
- Rapid deceleration after impact: I ran simulations using the mesh of my fixed diver models to see how the impact changes with the rapid deceleration that divers are experiencing. The results of my simulations studying the progression of the air cavity for rapidly decelerating entry bodies can be found in my dissertation.