Understanding fluid flow to enhance swimming performance

Sports scientists in Western Australia have been pioneering the use of computational fluid dynamics (CFD), the science of understanding fluid flow, to enhance the performance of Australian Olympic Swimming Team members.

They have been using CFD to model stroke performance. WAIS sports biomechanists have found that is more efficient to change a swimmer’s technique to reduce drag forces rather than solely increase the force applied by the swimmer. Clearly the more informed a swim coach is on the propulsive and resistive mechanisms of swimming movements, the greater the potential for performance increases
.
The project, based at the UWA Sports Park, is advancing existing applications of CFD to new levels by testing swimmers’ movement in dynamic positions. Previously the technology was viable only in static positions, such as the streamlined glide.

Using CFD allows sports scientists to understand for example the differences in propulsive forces generated from the feet versus those from the thighs and calves. It has also highlighted the generation of drag that occurs with certain body movements, such as when the knees are dropped too low on the downsweep, and the beneficial effects of increased ankle flexion on propulsion.

This takes the ‘trial and error’ approach out of technique prescription, as scientists and coaches can determine whether a change is beneficial without spending weeks changing a swimmer’s technique.

How does CFD modeling work?
To provide inputs into a dynamic CFD model, an accurate 3D shape of the swimmer is made using a whole body laser scanner that describes the swimmer’s geometry. It is also necessary to input the 3D kinematics (body movements) of the swimmer to animate the model based on how the subject moves in the water. The dynamic CFD model then calculates the way the water moves around this 3D animation to calculate the drag and propulsion that result from the movement.

Watch the video below to see how the technology has been used to model 50m freestyle world-record holder Eamon Sullivan’s stroke: