Unsteady computational fluid dynamics in front crawl swimming

Abstract

The development of codes and power calculations currently allows the simulation of increasingly complex flows, especially in the turbulent regime. Swimming research should benefit from these technological advances to try to better understand the dynamic mechanisms involved in swimming. An unsteady Computational Fluid Dynamics (CFD) study is conducted in crawl, in order to analyse the propulsive forces generated by the hand and forearm. The k-ω SST turbulence model and an overset grid method have been used. The main objectives are to analyse the evolution of the hand-forearm propulsive forces and to explain this relative to the arm kinematics parameters. In order to validate our simulation model, the calculated forces and pressures were compared with several other experimental and numerical studies. A good agreement is found between our results and those of other studies. The hand is the segment that generates the most propulsive forces during the aquatic stroke. As the pressure component is the main source of force, the orientation of the hand-forearm in the absolute coordinate system is an important kinematic parameter in the swimming performance. The propulsive forces are biggest when the angles of attack are high. CFD appears as a very valuable tool to better analyze the mechanisms of swimming performance and offers some promising developments, especially for optimizing the performance from a parametric study.

Relationships between a Load-velocity Profile and Sprint Performance in Butterfly Swimming

“…Due to the difficulty of quantifying the complex, unsteady flow profile around the whole body during swimming, it is currently not possible to measure both propulsive and resistive forces directly [3]. For this reason, there have been several estimative methods established that allow researchers to assess propulsive and/or resistive forces together with a swimming velocity, such as the MAD system [4], the velocity perturbation method [5], and the assisted towing method [6].…”

Front Crawl Is More Efficient and Has Smaller Active Drag Than Backstroke Swimming: Kinematic and Kinetic Comparison Between the Two Techniques at the Same Swimming Speeds

“…η O , overall efficiency; η P, propelling efficiency; η H , hydraulic efficiency; η F , Froude efficiency. during swimming is currently not possible due to a complex unsteady state of the water during swimming (Samson et al, 2017). However, the day-to-day variability of this method to assess D A of the same swimmers was reported to be around 3.0-6.5% (Narita et al, 2017).…”

Jean Vivès award 2019 hydrodynamic of swimming: analyse the flow to understand the technique

“…We have shown that the important kinematic parameters in the generation of propulsive forces are: the angle of attack of the fluid with respect to the hand, the orientation of the arms with respect to the direction of advancement, the velocity and acceleration of the hand and forearm. Optimal angles of attack range from 45 to 70 (Samson et al 2017). This corresponds to the angles we measured on expert swimmers: 62 on average during the insweep phase and 40 during the upsweep phase (Samson et al 2015).…”

“…At the same time, numerical simulations have been made using a Unsteady Reynolds Averaged Navier Stokes (URANS) method in order to obtain all the data (pressure, force, velocity) but also to follow the spatio-temporal evolution of the vortices over time. (Samson et al 2017(Samson et al , 2018b, Figure 1). These vortices play a key role in the generation of propulsive forces.…”