Browsing by Issue Date, starting with "2020-04-11"
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- Ciência com NúmerosPublication . Castro, EduardoO meu amigo João veio cá casa tomar um café. Enquanto aqueço a água, digo-lhe: “existe uma chávena no armário”. O João abre o armário. Et voilà! O João encontra uma chávena no armário. De acordo com a teoria da verdade como correspondência, a frase “existe uma chávena no armário” é verdadeira se, e só se, é um facto que existe uma chávena no armário. Para o caso, esta teoria supõe que existe um objecto no mundo exterior, numa dada localização espácio-temporal, que transforma a frase “existe uma chávena no armário” numa frase verdadeira.[...]
- Numerical Investigation of Frequency and Amplitude Influence on a Plunging NACA0012Publication . Camacho, E. A. R.; Neves, Fernando M. S. P.; Silva, A. R. R.; Barata, Jorge M MNatural flight has always been the source of imagination for Mankind, but reproducing the propulsive systems used by animals that can improve the versatility and response at low Reynolds number is indeed quite complex. The main objective of the present work is the computational study of the influence of the Reynolds number, frequency, and amplitude of the oscillatory movement of a NACA0012 airfoil in the aerodynamic performance. The thrust and power coefficients are obtained which together are used to calculate the propulsive efficiency. The simulations were performed using ANSYS Fluent with a RANS approach for Reynolds numbers between 8500 and 34,000, reduced frequencies between 1 and 5, and Strouhal numbers from 0.1 to 0.4. The aerodynamic parameters were thoroughly explored as well as their interaction, concluding that when the Reynolds number is increased, the optimal propulsive efficiency occurs for higher nondimensional amplitudes and lower reduced frequencies, agreeing in some ways with the phenomena observed in the animal kingdom.