Computational fluid dynamics as a tool for improving stroke technique

Biography

Dr Raymond Cohen completed his PhD in Computational Fluid Dynamics and Computational Acoustics at the University of Melbourne in 2009. He then joined the Computational Modelling Group of CSIRO Mathematics, Informatics and Statistics as a Postdoctoral Fellow to work on modelling of human swimming in collaboration with the Australian Institute of Sport. Now as a Research Scientist in CSIRO Computational Informatics, he continues to study human performance in aquatic sports (swimming, diving and kayaking) using computational fluid dynamics and biomechanical modelling.

Synopsis

Elite competitive swimming is a sport in which the difference between winning and losing can be a fraction of a second. Swimmers and their coaches are always striving to optimise stroke technique to get an edge over their rivals. However optimal technique varies across individuals because swimmer performance depends on a complex interplay between fluid dynamics, swimmer biomechanics and physiology. Computational fluid dynamics (CFD) is an emerging technology that offers new opportunities for experimentation with stroke technique to complement the well established pool based experimentation methods. In CFD, experiments are conducted in a virtual environment with a biomechanical model of the swimmer in a computational model of the pool. Individual aspects of stroke can be modified in isolation, providing a controlled and repeatable testing environment. The resulting performance changes can be analysed and the underlying physical mechanisms can be explained. The results are then fed back to the coaches to help inform further testing of stroke technique. Other sports that already benefit from CFD modelling include motor sports, sailing, many winter Olympic sports and cycling.

CFD modelling of swimming requires a biomechanical model of the swimming athlete. This model is generated from a combination of laser body scan of the athlete in an anatomical pose and motion captured swimming kinematics. The model is then placed into the virtual pool and allowed to swim freely. The performance from this baseline case is then analysed. Previously immeasurable quantities about the stroke can be determined from the CFD results including individual forces on limbs, swimming efficiencies and internal swimmer biomechanics including joint torques, joint powers and muscle forces. The coaches and scientists can then modify stroke details of the baseline digitised swimming stroke to see what impacts the changes have on all the performance metrics.

A number of CFD studies have been conducted on swimming stroke technique in a partnership between CSIRO and AIS. Highlights of these studies are presented along with an overview of the leading edge studies being conducted overseas. This presentation will also look towards the future where CFD will become a tool which is routinely used by elite level swimmers and coaches to improve stroke technique.