This study examined whether Sanders' model is suitable for estimating accurately the propulsive force generated by the hands' motion in swimming comparing the calculated force obtained using the model and the measured force during an actual propulsive action. The measured and calculated forces were obtained from 13 swimmers who, while tethered, performed a sculling motion in a prone position for the purpose of displacing the body by moving it forward. Kinematic analyses were conducted to obtain the calculated force, while the measured force was obtained via the use of a load cell. The calculated force was lower than the measured force and accounted for only a small part of the variation in the measured force. The forces could not be used interchangeably, and there were fixed and proportional differences between them. Consequently, this study indicates that Sanders' model is not suitable for estimating accurately the propulsive force generated by the swimmer's hands during sculling motion. However, research that integrates analyses from different approaches could result in improvements to the model that would render it applicable for estimating the propulsive forces during movements that are characterised by directional changes of the hands.
This work aims to study a two-dimensional incompressible flow around a cylinder in forced movement in order to understand the phenomena that occur in cylindrical structures under periodic oscillation using the Direct Numerical Simulation technique. The simulations were taken using the computational code named Incompact3d. It was used the Reynolds Number as 400 in all simulations. The trajectories transversal and eight shapes were simulated for a range of displacement amplitude. The Navier-Stokes and continuity equations were used to discretize the flow in a Cartesian mesh. It was used the third-order RungeKutta scheme with low-storage for the pass-time and the body was represented by the virtual boundary method. The temporal mean of the drag and lift coefficients and vortex shedding mode were computed. The results show large variations of the mean lift coefficient with the amplitude displacement for all trajectories, and so altering the vortex shedding mode. The 2S mode was observed for simulations with transversal trajectories, except for amplitude of 0.55D, which presented the 2P mode. Simulations with eight trajectory presented 2P mode in most cases, and for certain amplitudes the periodic shedding modes were not observed. I. INTRODUÇÃOO escoamento ao redor de cilindros tem sido abordado por diversos pesquisadores pelo fato da geometria cilíndrica ser de fácil implementação experimental e numérica, além de ter uma vasta aplicação.Escoamentos turbulentos ao redor de obstáculos produzem fenômenos como esteira de vórtices e forças hidrodinâmicas sobre esses obstáculos. Quandoé imposta uma determinada trajetória ao cilindro, os padrões da esteira de vórtices e as forças sobre este podem ser alteradas significativamente. A vibração induzida por vórtices ocorre com frequência em estruturas como os risers (Fig. 1), condutos responsáveis pela captação de petróleo do fundo do oceano e transporte até a plataforma. Este fenômeno pode provocar oscilações, causando danos ao equipamento. Vários trabalhos têm sido realizados utilizando DNS graçasà evolução das ferramentas Fig. 1: Risers, condutos transportadores de petróleo. Fonte:de cálculo e métodos numéricos, pois a solução das equações que descrevem os escoamentos precisa de computadores poderosos como os que existem hoje. Este trabalho tem por objetivo estudar o escoamento bidimensional ao redor de um cilindro em movimento forçado, com trajetórias transversal e em oito, bem como analisar as forças hidrodinâmicas e o padrão de vórtices que se desprendem. II. METODOLOGIA A. Configuração do EscoamentoPara realizar as simulações foi usado o código fonte Incompact3d [1], capaz de simular escoamentos turbulentos tridimensionais ao redor de obstáculos. O cilindroé forçado a percorrer dois tipos de trajetórias: uma transversal e a outra em "8" (oito), nas quais as amplitudes de movimento do cilindro são A x (no sentido do escoamento principal) e A y (transversal ao escoamento principal), mostradas na Fig. 2. Ambas amplitudes são quantificadas em diâmetros de cilindro, "D". O es...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.