| Summary: | 碩士 === 淡江大學 === 航空太空工程學系碩士班 === 98 === The objective of this research is to study the energy saving mechanism of group-swimming fish via numerical simulation. Two-dimensional Navior-Stokes equations have been solved in a viscous, incompressible flow with Re = 5000. For better swimming performance, the Strouhal number was set at 0.3. Simulations with various spacing (s = 1.25L、1.35 L、1.5 L、1.65 L、1.75 L、2 L, where L is the length of the fish) between the fish in stream-wise direction have been carried out to find the optimum value. Results showed that, due to the suction effect induced by low pressure wake region caused by tail sweeping of the fish at the upstream side, power consumption of the fish with s = 1.5 L downstream-wise was 45% less than that when swimming alone. However, with spacing s = 1.25 L, the power consumption of the downstream side of the fish was only 9% less than that when swimming alone. Since the low pressure suction effect was dissipated gradually by viscosity, the influence from the upstream side of the fish upon the downstream side of the fish became smaller when the spacing was greater than 1.5 L. Thus, the benefit of energy saving in group swimming became less distinct.
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