The effects of caudal fin's bending stiffness on a self-propelled carangiform swimmer

Wu, Buchen1,2; Shu, Chang2; Lee, HsuChew1,3; Wan, Minping1,3

2022-04-01

10.1063/5.0089082

PHYSICS OF FLUIDS   影响因子和分区

1070-6631

1089-7666

The hydrodynamic performance of a self-propelled carangiform swimmer with a flexible caudal fin in the absence of a free stream is numerically investigated, where the fin's dimensionless bending stiffness varies from 10(-3) to 150. It reveals that large flexibility of the caudal fin has a negative impact on the propulsion and moderate rigidity is found to increase the hydrodynamic performance. Two different vortex configurations are observed at low and high bending stiffnesses: (i) reverse Benard-von Karman (rBvK) vortex configuration and (ii) deflected reverse Benard-von Karman wake with the secondary vortex street, respectively. With the increase in bending stiffness, the thrust-producing part switches from the swimmer body to the caudal fin corresponding to the switch of the vortex configuration. Furthermore, the thrust and drag productions are examined. As the bending stiffness increases, the "active portion" of the caudal fin provides more kinetic energy to the wake flow. It is found that the deflected rBvK is induced by the vortical strength imbalance of two adjacent vortices, and the secondary vortex street is formed by the large strain between the primary vortex and the secondary vortex street. Meanwhile, the dynamic mode decomposition analysis indicates that the dominant mode of the dynamic flow field is the excited frequency resonant mode and the inherent frequency of the secondary vortex street is the same as the undulatory frequency. These results shed new light onto the role of the flexible caudal fin in self-propelled biological systems and may provide some inspirations to autonomous underwater vehicle design. Published under an exclusive license by AIP Publishing.

SCI ; EI

英语

第一 ; 通讯

Department of Science and Technology of Guangdong Province[2020B1212030001] ; Key-Area Research and Development Program of Guangdong Province[2021B0101190003] ; Shenzhen Science and Technology Program[KQTD20180411143441009]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:000788720700023

AIP Publishing

20221712039918

Autonomous underwater vehicles ; Fins (heat exchange) ; Hydrodynamics ; Kinetic energy ; Kinetics ; Stiffness ; Vortex flow

Heat Exchange Equipment and Components:616.1 ; Fluid Flow, General:631.1 ; Small Marine Craft:674.1 ; Classical Physics; Quantum Theory; Relativity:931 ; Materials Science:951

PHYSICS

Web of Science

1.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Guangdong Prov Key Lab Turbulence Res & Applicat, Shenzhen 518055, Guangdong, Peoples R China
2.Natl Univ Singapore, Dept Mech Engn, 10 Kent Ridge Crescent, Singapore 119260, Singapore
3.Southern Univ Sci & Technol, Guangdong Hong Kong Macao Joint Lab Data Driven F, Shenzhen 518055, Peoples R China

Wu, Buchen,Shu, Chang,Lee, HsuChew,et al. The effects of caudal fin's bending stiffness on a self-propelled carangiform swimmer[J]. PHYSICS OF FLUIDS,2022,34(4).

Wu, Buchen,Shu, Chang,Lee, HsuChew,&Wan, Minping.(2022).The effects of caudal fin's bending stiffness on a self-propelled carangiform swimmer.PHYSICS OF FLUIDS,34(4).

Wu, Buchen,et al."The effects of caudal fin's bending stiffness on a self-propelled carangiform swimmer".PHYSICS OF FLUIDS 34.4(2022).