Fluid Mechanics in Rowing: The Case of the Flow Around the Blades (original) (raw)
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Numerical modelling of rowing blade hydrodynamics
Sports Engineering, 2009
The highly unsteady flow around a rowing blade in motion is examined using a three-dimensional computational fluid dynamics (CFD) model which accounts for the interaction of the blade with the free surface of the water. The model is validated using previous experimental results for quarter-scale blades held stationary near the surface in a water flume. Steady-state drag and lift coefficients from the quarter-scale blade flume simulation are compared to those from a simulation of the more realistic case of a full-scale blade in open water. The model is then modified to accommodate blade motion by simulating the unsteady motion of the rowing shell moving through the water, and the sweep of the oar blade with respect to the shell. Qualitatively, the motion of the free surface around the blade during a stroke shows a realistic agreement with the actual deformation encountered during rowing. Drag and lift coefficients calculated for the blade during a stroke show that the transient hydrodynamic behaviour of the blade in motion differs substantially from the stationary case.
Procedia Engineering, 2010
A hydrodynamics-based model of the highly complex flow around a rowing oar blade during a rowing stroke, consisting of an analytical shell velocity model fully coupled with a computational fluid dynamics (CFD) model, is presented. A temporal examination of the resulting blade force for a standard blade, decomposed into propulsive, drag, and lift components, illustrates the flow mechanisms responsible for shell propulsion and a blade propulsive efficiency term is defined. A comparison of blades with modified cant angles reveals that a-3° cant blade has a higher efficiency than the standard (-6° cant) blade.
Simulation of the dynamics of an olympic rowing boat
2008
Abstract A tool for the prediction of the performance of olympic rowing boats is presented and discussed. The equations of motion include the full dynamics of the boat, oars and oarsmen and are obtained by modelling the rowers motion, oar forces and fluid-structure intercation forces. The proposed algorithm is implemented in a C++ code which has proved to produce consistent results for any crew configuration tested.
Computational study of the Froude number effects on the flow around a rowing blade
2009
We consider some scale model experiments in which the forces on rowing blades were measured [Caplan and Gardner, J. Sport Sciences, 25(6), 653-650, 2007]. The experiments were conducted in a flume at a single flow velocity which corresponded to a Froude number, based on the depth dimension of the blade, very close to the critical value of unity. For real rowing, the blade moves at speeds corresponding to Froude numbers in the range of approximately 0.3 to 3.5. We use a computational fluid dynamics (CFD) analysis to investigate the Froude and Reynolds number effects on the forces on a flat plate 'blade', as well as the effects of the flume size relative to the model size in the experiments. We consider only one orientation of the plate to the flow velocity and we consider only idealized steady flow. We find that the flume in the experiments was probably too shallow, so that the measured force coefficients could be 6% higher than for rowing in deep water. Using a series of calculations for fluids with different densities, we show that the force coefficient is independent of the Reynolds number for the range of Reynolds numbers characteristic of real rowing, but is a strong function of the Froude number. There is a sudden decrease of some 30% in the force coefficient as the Froude number changes from sub-critical (less than 1) to super-critical (greater than 1). For Froude numbers greater than 2 the force coefficient increases steadily with Froude number.
The direction of the water force on a rowing blade and its effect on efficiency
Introduction. 2. Direction of the blade force. 3. Steady flow, model tests. 4. Blade and airfoil compared. 5. Outward tangential force component. 6. Blade velocity relative to water. 7. Efficiency. 8. Typical kinematic values near catch and square-off. 9. Oar bending. 10. Possible hydrodynamic effect. 11. Conclusion.
Fluid-Structure Interaction and High-Performance Computing to serve sport performance in rowing
2019
With the tremendous growth of computational power, the use of numerical simulations to help analysing and improving sport performance becomes achievable but is still challenging because the physical configurations generally involved coupled problems and because a human is part of the system. Futher-more, elite athletes already operate near an optimal point. As a consequence, the modelization of all the phenomena that come into play has to be accurate enough to be useful and relevant when the objective is to analyse interactions and to give reliable trends while varying some parameters. The case of rowing is presented here, through the development of a high-fidelity simulator of the global system "boat-oars-rower(s)" coupled with the resolution of the Navier-Stokes equations to provide fluid forces acting on it. For this nautical sport, the complexity comes from the non-classical naval hydrodynamics flows around the hull and the blades and from the fluid-structure interacti...
A model for the dynamics of rowing boats
2008
Abstract A model of a rowing scull has been developed, comprising the full motion in the symmetry plane and the interaction with the hydrodynamics. A particular emphasis has been given to the energy dissipation due to the secondary movements activated by the motion of the rowers and the intermittent forcing terms. Numerical simulations show the effectiveness of the proposed procedure. Copyright© 2008 John Wiley & Sons, Ltd.
Sprint Canoe Blade Hydrodynamics - Modeling and On-water Measurement
Procedia Engineering, 2016
A computational fluid dynamics model of the transient flow around a sprint canoe blade has been developed including the full blade motion in the catch and draw phases of the stroke, with the translational and rotational path of the blade is obtained from video analysis of a national team athlete. Examination of the blade path and associated flow patterns around the blade reveals the development of tip and side vortices and their interaction with the blade. An interval of reversed flow and pressure at the top of the blade late in the catch is seen and results in a braking pressure field on the blade surface. On-water measurements have also been made using a new instrumented paddle with multiple strain gauge full bridges. This level of bending moment measurement then allows the tracking of the real centre of pressure of the blade force and the determination of the real blade force (and its components) through the stroke.
Performance Prediction of Olympic Rowing Boats Accounting for Full Dynamics
2007
The periodic forces imposed at the oars and due to the movement of the rowers induce a secondary motion on the scull, causing an additional drag which may represent a significant part of total dissipated energy. We have taken the approach of computing the complete scull motion including pitching, vertical and horizontal movement. A full dynamic model requires simulating rowers inertial forces, thrust forces at the oarlocks and fluid-dynamic forces.
Validated biomechanical model for efficiency and speed of rowing
Journal of biomechanics, 2014
The speed of a competitive rowing crew depends on the number of crew members, their body mass, sex and the type of rowing-sweep rowing or sculling. The time-averaged speed is proportional to the rower's body mass to the 1/36th power, to the number of crew members to the 1/9th power and to the physiological efficiency (accounted for by the rower's sex) to the 1/3rd power. The quality of the rowing shell and propulsion system is captured by one dimensionless parameter that takes the mechanical efficiency, the shape and drag coefficient of the shell and the Froude propulsion efficiency into account. We derive the biomechanical equation for the speed of rowing by two independent methods and further validate it by successfully predicting race times. We derive the theoretical upper limit of the Froude propulsion efficiency for low viscous flows. This upper limit is shown to be a function solely of the velocity ratio of blade to boat speed (i.e., it is completely independent of the...