This paper investigates the swimming performance of fish undulatory motion which is the basic form in locomotion of aquatical animal from a hydrodynamics point of view.In particular,the propulsive characteristics is d...This paper investigates the swimming performance of fish undulatory motion which is the basic form in locomotion of aquatical animal from a hydrodynamics point of view.In particular,the propulsive characteristics is discussed.The three-dimensional potential flow over a model rectangular flexible plate performing the motion which consists of a progressive wave of a given wave length and phase velocity along the chord is treated.Vortex ring method is used to calculate the thrust,the power required and the hydrodynamic propulsive efficiency,etc.The dependence of these energetics on certain physical parameters,such as the aspect ratio,the reduced frequency and the wave number,is discussed.It is found that as the wave tength gets close to the body length,propulsive performance is no longer sensitive to the aspect ratio.Some qualitative explanation of the fish swimming phenomena is also given.展开更多
This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the ...This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the fluid.The algorithm used for solving Fluid-Structure Interactions(FSI)involving the immersed structure with changeable shapes is based on the momentum redistribution method.The present approach excludes the need to solve elastic equations,obtain high-accuracy predictions of the flow field and provide a rigorous basis for implementing the Immersed Boundary Method(IBM).The OpenFOAM implementation of the algorithm is discussed along with the design methodology for developing bio-inspired underwater vehicles using the present solver.The computational results are validated with the experimental observations of the two-dimensional and three-dimensional anguilliform swimmer case studies.The study further extended to the three-dimensional hydrodynamics of a bioinspired,self-propelling manta bot.The motion of the body is specified a priori according to the reported experimental observations.The results quantify the vortex formation and shedding processes and enable the identification of the portions of the body responsible for the majority of thrust.The body accelerates from rest to an asymptotic mean forward velocity of 0.2 ms^(-1)in almost 5 s,consistent with experimental observations.It is observed that the developed computational model is capable of performing any motion simulation and manoeuvrability analysis,which are critical for the designers to develop novel unmanned underwater vehicles.展开更多
文摘This paper investigates the swimming performance of fish undulatory motion which is the basic form in locomotion of aquatical animal from a hydrodynamics point of view.In particular,the propulsive characteristics is discussed.The three-dimensional potential flow over a model rectangular flexible plate performing the motion which consists of a progressive wave of a given wave length and phase velocity along the chord is treated.Vortex ring method is used to calculate the thrust,the power required and the hydrodynamic propulsive efficiency,etc.The dependence of these energetics on certain physical parameters,such as the aspect ratio,the reduced frequency and the wave number,is discussed.It is found that as the wave tength gets close to the body length,propulsive performance is no longer sensitive to the aspect ratio.Some qualitative explanation of the fish swimming phenomena is also given.
基金the funding received from Naval Research Board,Marine System Panel to carry out this research work at Shiv Nadar University.Award Number:NRB/4003/PG/400,Recipient:Dr.Santanu Mitra,Ph.D.,Assoc.Professor,Mechanical Engineering Department,Shiv Nadar University.
文摘This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the fluid.The algorithm used for solving Fluid-Structure Interactions(FSI)involving the immersed structure with changeable shapes is based on the momentum redistribution method.The present approach excludes the need to solve elastic equations,obtain high-accuracy predictions of the flow field and provide a rigorous basis for implementing the Immersed Boundary Method(IBM).The OpenFOAM implementation of the algorithm is discussed along with the design methodology for developing bio-inspired underwater vehicles using the present solver.The computational results are validated with the experimental observations of the two-dimensional and three-dimensional anguilliform swimmer case studies.The study further extended to the three-dimensional hydrodynamics of a bioinspired,self-propelling manta bot.The motion of the body is specified a priori according to the reported experimental observations.The results quantify the vortex formation and shedding processes and enable the identification of the portions of the body responsible for the majority of thrust.The body accelerates from rest to an asymptotic mean forward velocity of 0.2 ms^(-1)in almost 5 s,consistent with experimental observations.It is observed that the developed computational model is capable of performing any motion simulation and manoeuvrability analysis,which are critical for the designers to develop novel unmanned underwater vehicles.
