Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynami...Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.展开更多
The flow and heat transfer characteristics, including transition critical Reynolds number from two-dimensional to three-dimensional, the influence of slit-cylinder geometric parameter on Strouhal number, Nusselt numbe...The flow and heat transfer characteristics, including transition critical Reynolds number from two-dimensional to three-dimensional, the influence of slit-cylinder geometric parameter on Strouhal number, Nusselt number and forces acting on the slit-cylinder are numerically investigated. It's found that transition critical Reynolds number from two-dimensional(flow wake deforms in two directions) to three-dimensional(flow wake deforms in three directions) increases with the augment of the slit width ratio in the range of present considered Reynolds number. The present results indicate that the three-dimensional vortex structures resulting from the deformation of the vortex shedding have significant effects on flow and heat transfer features such as Strouhal number, Nusselt number and forces acting on the cylinders with different ratios of slit width. It's observed that the drag and lift coefficients reduce as the increase of slit width ratio, and vortex shedding is effectively suppressed by the slits.Moreover, the comprehensive heat transfer performance of the cylinder with the slits is significantly improved with the increase of the slit width ratio.展开更多
基金the support of National Natural Science Foundation of China (Grant No.10672183)
文摘Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.
文摘The flow and heat transfer characteristics, including transition critical Reynolds number from two-dimensional to three-dimensional, the influence of slit-cylinder geometric parameter on Strouhal number, Nusselt number and forces acting on the slit-cylinder are numerically investigated. It's found that transition critical Reynolds number from two-dimensional(flow wake deforms in two directions) to three-dimensional(flow wake deforms in three directions) increases with the augment of the slit width ratio in the range of present considered Reynolds number. The present results indicate that the three-dimensional vortex structures resulting from the deformation of the vortex shedding have significant effects on flow and heat transfer features such as Strouhal number, Nusselt number and forces acting on the cylinders with different ratios of slit width. It's observed that the drag and lift coefficients reduce as the increase of slit width ratio, and vortex shedding is effectively suppressed by the slits.Moreover, the comprehensive heat transfer performance of the cylinder with the slits is significantly improved with the increase of the slit width ratio.
