Research on the hydrodynamic performance and wake structure evolution of bionic vehicles under multiple arrangement configurations and optimization strategies

ObjectivesThis study addresses the widespread application of biomimetic navigational vehicles across various fields, focusing on the complexities of propulsion mechanisms in collective operations. It aims to fill the research gap regarding the impact of arrangement and spatial configurations on performance. By exploring the effects of different arrangements and spatial strategies on propulsion efficiency, this work provides theoretical support and practical guidance for relevant applications. MethodsThis study employs the computational fluid dynamics (CFD) software Fluent, utilizing the finite volume method for the discretization of governing equations and integrating advanced algorithms for high-precision numerical simulations. A user-defined function (UDF) was developed to simulate the flexible deformation of biomimetic fish boundaries. Additionally, innovative numerical simulations were conducted using various arrangement configurations to investigate their effects on flow field characteristics and propulsion performance.ResultsFor staggered arrangements of biomimetic fish, the thrust coefficient is low at Gx = 0 due to the cancellation of positive and negative vorticity between the two fish. In the range 0 < Gx < 1 the thrust coefficient of Fish #1 initially decreases and then increases, reaching a maximum at Gx = 1, while Fish #2 shows an initial increase followed by a decrease, peaking at Gx = 0.5. In triangular arrangements, Fish #1 experiences a decrease in thrust coefficient due to the low-pressure zone between the downstream fish, with smaller lateral spacing Gy leading to lower thrust. At Gx = 0 the thrust coefficient is low for the downstream fish, increasing and then decreasing with increasing Gx, indicating strong interference only occurs at smaller Gx. In rectangular arrangements, the thrust coefficients of all four fish increase with larger Gy, suggesting that close lateral spacing results in adverse interference. At smaller Gx, the upstream fish benefit from the high-pressure zone created by the downstream fish, while the downstream fish are affected by the upstream fish's wake, causing the thrust coefficient to exhibit oscillatory behavior with changes in Gx.ConclusionIn adjacent arrangements of biomimetic fish, significant interference occurs within the flow fields at smaller spacings (0 < Gx, Gy < 1.0), leading to substantial fluctuations in the average thrust coefficient. As the spacing increases, the interference diminishes, and the average thrust coefficient approaches that of a single fish. Furthermore, under specific spacing configurations, each fish in the cluster can generate a thrust coefficient higher than that of an individual fish; conversely, inappropriate spacing may reduce the thrust coefficient. These findings provide scientific insights for optimizing spacing in clustered biomimetic fish for underwater operations, enhancing hydrodynamic advantages and propulsion efficiency, and offer guidance for the research and development of efficient underwater vehicles.