Browsing by Author "Ramos, Rui J."
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- Assessment of passive drag in swimming by numerical simulation and analytical procedurePublication . Barbosa, Tiago M.; Ramos, Rui J.; Silva, A.J.; Marinho, D.A.The aim was to compare the passive drag-gliding underwater by a numerical simulation and an analytical procedure. An Olympic swimmer was scanned by computer tomography and modelled gliding at a 0.75-m depth in the streamlined position. Steady-state computer fluid dynamics (CFD) analyses were performed on Fluent. A set of analytical procedures was selected concurrently. Friction drag (Df), pressure drag (Dpr), total passive drag force (Df +pr) and drag coefficient (CD) were computed between 1.3 and 2.5 m · s−1 by both techniques. Df +pr ranged from 45.44 to 144.06 N with CFD, from 46.03 to 167.06 N with the analytical procedure (differences: from 1.28% to 13.77%). CD ranged between 0.698 and 0.622 by CFD, 0.657 and 0.644 by analytical procedures (differences: 0.40–6.30%). Linear regression models showed a very high association for Df +pr plotted in absolute values (R2 = 0.98) and after log–log transformation (R2 = 0.99). The CD also obtained a very high adjustment for both absolute (R2 = 0.97) and log–log plots (R2 = 0.97). The bias for the Df +pr was 8.37 N and 0.076 N after logarithmic transformation. Df represented between 15.97% and 18.82% of the Df +pr by the CFD, 14.66% and 16.21% by the analytical procedures. Therefore, despite the bias, analytical procedures offer a feasible way of gathering insight on one’s hydrodynamics characteristic
- Computational fluid dynamics: the analysis of drag coefficient during the gliding phasePublication . Marinho, D.A.; Ramos, Rui J.; Mantha, Vishveshwar; Barbosa, Tiago M.; Rouboa, Abel; Silva, A.J.The aim of the current study was to analyse the effect of depth on hydrodynamic drag coefficient during the underwater gliding, using computational fluid dynamics.
- Dinâmica computacional de fluidos: análise do coeficiente de arrasto durante o deslize subaquáticoPublication . Ramos, Rui J.; Marinho, D.A.; Mantha, Vishveshwar; Barbosa, Tiago M.; Rouboa, Abel; Ribeiro, João; Machado, Leandro; Vilas-Boas, João Paulo; Silva, A.J.O objectivo deste estudo foi analisar o efeito da profundidade no arrasto hidrodinâmico durante o deslize subaquático, utilizando a dinâmica computacional de fluidos.
- The effect on swimmer’s hydrodynamic drag wearing two swimsuitsPublication . Marinho, D.A.; Mantha, Vishveshwar; Ramos, Rui J.; Barbosa, Tiago M.; Vilas-Boas, João Paulo; Rouboa, Abel; Silva, A.J.