Topology Optimization of the Caudal Fin of the Three-Dimensional Self-Propelled Swimming Fish

2014 ◽  
Vol 6 (06) ◽  
pp. 732-763 ◽  
Author(s):  
Zhiqiang Xin ◽  
Chuijie Wu
Keyword(s):  
Topology Optimization ◽  
Swimming Speed ◽  
Moving Boundary ◽  
Swimming Performance ◽  
Three Dimensional ◽  
The Body ◽  
Caudal Fin ◽  
Swimming Efficiency ◽  
Vorticity Flux ◽  
3D Topology

AbstractBased on the boundary vorticity-flux theory, topology optimization of the caudal fin of the three-dimensional self-propelled swimming fish is investigated by combining unsteady computational fluid dynamics with moving boundary and topology optimization algorithms in this study. The objective functional of topology optimization is the function of swimming efficiency, swimming speed and motion direction control. The optimal caudal fin, whose topology is different from that of the natural fish caudal fin, make the 3D bionic fish achieve higher swimming efficiency, faster swimming speed and better maneuverability. The boundary vorticity-flux on the body surface of the 3D fish before and after optimization reveals the mechanism of high performance swimming of the topology optimization bionic fish. The comparative analysis between the swimming performance of the 3D topology optimization bionic fish and the 3D lunate tail bionic fish is also carried out, and the wake structures of two types of bionic fish show the physical nature that the swimming performance of the 3D topology optimization bionic fish is significantly better than the 3D lunate tail bionic fish.

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

Kinematics of Pectoral Fin Propulsion in Cymatogaster Aggregata

1973 ◽  
Vol 59 (3) ◽  
pp. 697-710 ◽  
Author(s):  
P. W. WEBB
Keyword(s):  
Swimming Speed ◽  
Performance Test ◽  
Beat Frequency ◽  
The Body ◽  
Fish Swimming ◽  
Pectoral Fin ◽  
Caudal Fin ◽  
Lift Forces ◽  
Time Of Year ◽  
Refractory Phase

1. The kinematics of pectoral-fin propulsion have been measured for Cymatogaster aggregata, 14·3 cm in length, during an increasing-velocity performance test. Acclimation and test temperature was 15 °C, similar to the fishes' normal environmental temperature for the time of year of the tests. 2. Locomotion was in the labriform mode. Within this mode two pectoral-fin patterns were observed, differing only in the details of fin kinematics. These differences resulted from the length of the propagated wave passed over the fin. At low swimming speeds, up to about 2 L/sec, the wavelength was relatively short, approximately twice the length of the trailing edge of the fin. At higher speeds, a wave of very much longer wavelength was passed over the fin. 3. The pectoral fin-beat cycle was divisible into abduction, adduction and refractory phases. Abduction and adduction phases were of equal duration, and the proportion of time occupied by these phases increased with swimming speed. The duration of the refractory phase decreased with increasing speed. 4. The kinematics indicated that thrust was generated throughout abduction and adduction phases, together with lift forces that cancelled out over a complete cycle. As a result of lift forces and the refractory phase the body moved in a figure-8 motion relative to the flow. 5. Pectoral fin-beat frequency and amplitude increased with swimming speed, and the product of frequencyxamplitude was linearly related to swimming speed. 6. Interactions between pectoral fin-beat frequency, amplitude, refractory phase and kinematic patterns were interpreted as a mechanism to permit the propulsive muscles to operate at optimum efficiency and power output over a wider range of swimming speeds than would otherwise be possible. 7. Pectoral-fin propulsion was augmented by caudal-fin propulsion only at swimming speeds greater than 3·4 L/sec. 8. The mean 45 min critical swimming speed was 3·94 L/sec, and compares favourably with similar levels of activity for fish swimming by means of body and caudal-fin movements.

The Swimming Energetics of Trout

1971 ◽  
Vol 55 (2) ◽  
pp. 521-540 ◽  
Author(s):  
P. W. WEBB
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Swimming Performance ◽  
The Body ◽  
Control Group ◽  
Muscle System ◽  
Rate Of Oxygen Consumption ◽  
Wet Weight ◽  
Standard Rate ◽  
The Difference

1. The oxygen consumption of rainbow trout was measured at a variety of subfatigue swimming speeds, at a temperature of 15 %C. Five groups of fish were used, a control group and four groups with extra drag loads attached to the body. 2. The logarithm of oxygen consumption was linearly related to swimming speed in all five groups, the slope of the relationship increasing with the size of the extra drag load. The mean standard rate of oxygen consumption was 72.5 mg O2/kg wet weight/h. The active rate of oxygen consumption was highest for the control group (628 mg O2/kg/h) and fell with increasing size of the attached drag load. The active rate for the control group was high in comparison with other salmonid fish, and in comparison with the value expected for the fish. This was not a result of the extra drag loads in the other groups. No explanation for this high value can be found. 3. The critical swimming speed for a 60 min test period was 58.1 cm/sec (2.0 body lengths/sec) for the control group. The values for the critical swimming speeds were slightly higher than those measured for the same species in a previous paper (Webb, 1971). The difference between the two sets of critical swimming speeds is attributed to seasonal changes in swimming performance. 4. The aerobic efficiency was found to reach values of 14.5-15.5% based on the energy released by aerobic metabolism in comparison with the calculated required thrust. 5. The anaerobic contribution to the total energy budget in increasing-velocity tests is considered to be small, and can be neglected. 6. It is concluded that the efficiency of the muscle system in cruising will be approximately 17-20% over the upper 80% of the cruising-speed range, while the caudal propeller efficiency will increase from about 15-75 % over the same range. 7. Consideration of the efficiency values for the caudal propeller calculated here, and those predicted by Lighthill's (1969) model of fish propulsion, suggest that the efficiency of the propeller system will reach an optimum value at the maximum cruising speeds of most fish, and will remain close to this value at spring speeds.

How dorsal fin sharpness affects swimming speed and economy

2019 ◽  
Vol 878 ◽  
pp. 370-385 ◽  
Author(s):  
Qiang Zhong ◽  
Haibo Dong ◽  
Daniel B. Quinn
Keyword(s):  
Swimming Speed ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Cross Flow ◽  
Leading Edge ◽  
Caudal Fin ◽  
Fish Model ◽  
Dorsal Fin ◽  
Flow Interactions ◽  
Edge Vortex

Multi-fin systems, like fish or fish-inspired vehicles, are governed by unsteady three-dimensional interactions between their multiple fins. In particular, dorsal/anal fins have received much attention because they are just upstream of the main thrust-producing fin: the caudal (tail) fin. We used a tuna-inspired fish model with variable fin sharpness to study the interaction between elongated dorsal/anal fins and caudal fins. We found that the performance enhancement is stronger than previously thought (15 % increase in swimming speed and 50 % increase in swimming economy) and is governed by a three-dimensional dorsal-fin-induced cross-flow that lowers the angle of attack on the caudal fin and promotes spanwise flow. Both simulations and multi-layer particle image velocimetry reveal that the cross-flow stabilizes the leading edge vortex on the caudal fin, similar to how wing strakes prevent stall during fixed-wing aircraft manoeuvres. Unlike other fin–fin interactions, this mechanism is phase-insensitive and offers a simple, passive solution for flow control over oscillating propulsors. Our results therefore improve our understanding of multi-fin flow interactions and suggest new insights into dorsal/anal fin shape and placement in fish and fish-inspired vehicles.

A transient three-dimensional analysis of non-uniform dislocation distribution growth by climb and glide over non-planar surfaces

1986 ◽  
Vol 407 (1833) ◽  
pp. 299-311 ◽  
Keyword(s):  
Moving Boundary ◽  
Three Dimensional ◽  
Elastic Solid ◽  
Symmetric Tensor ◽  
The Body ◽  
Displacement Discontinuity ◽  
Dynamic Crack ◽  
3D Analysis ◽  
Equivalent Representation ◽  
Planar Surfaces

As a basis for obtaining insight into both plastic flow described in terms of dislocation motion and dynamic crack extension, a transient 3D analysis of the non-uniform growth of dislocation distributions by climb and glide over largely arbitrary non-planar surfaces is considered. An exact solution for the case of an unbounded, isotropic, homogeneous, linearly elastic solid is obtained in vector form. It is found that information about essential distribution and surface properties are contained in the solution in a symmetric tensor. This tensor arises as a generalized consequence of the body-force equivalent representation of dislocations in elastic continua. The solution is also found to have two components: one component depends on the velocity discontinuity induced across the surface, the other depends on the displacement discontinuity at the moving boundary of the distribution and the speed of the boundary. Two examples are then considered to illustrate the utility of the solution.

scholarly journals Three-dimensional topology optimization model to simulate the external shapes of bone

2021 ◽  
Vol 17 (6) ◽  
pp. e1009043
Author(s):  
Misaki Sakashita ◽  
Shintaro Yamasaki ◽  
Kentaro Yaji ◽  
Atsushi Kawamoto ◽  
Shigeru Kondo
Keyword(s):  
Topology Optimization ◽  
Internal Structure ◽  
Optimization Model ◽  
External Load ◽  
Muscle Tension ◽  
Three Dimensional ◽  
Bone Diseases ◽  
The Body ◽  
External Loads ◽  
External Shape

Elucidation of the mechanism by which the shape of bones is formed is essential for understanding vertebrate development. Bones support the body of vertebrates by withstanding external loads, such as those imposed by gravity and muscle tension. Many studies have reported that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that bone shape adapts to external load. In fact, by simulating this relationship through topology optimization, the internal trabecular structure of bones can be successfully reproduced, thereby facilitating the study of bone diseases. In contrast, there have been few attempts to simulate the external structure of bones, which determines vertebrate morphology. However, the external shape of bones may be reproduced through topology optimization because cells of the same type form both the internal and external structures of bones. Here, we constructed a three-dimensional topology optimization model to attempt the reproduction of the external shape of teleost vertebrae. In teleosts, the internal structure of the vertebral bodies is invariable, exhibiting an hourglass shape, whereas the lateral structure supporting the internal structure differs among species. Based on the anatomical observations, we applied different external loads to the hourglass-shaped part. The simulations produced a variety of three-dimensional structures, some of which exhibited several structural features similar to those of actual teleost vertebrae. In addition, by adjusting the geometric parameters, such as the width of the hourglass shape, we reproduced the variation in the teleost vertebrae shapes. These results suggest that a simulation using topology optimization can successfully reproduce the external shapes of teleost vertebrae. By applying our topology optimization model to various bones of vertebrates, we can understand how the external shape of bones adapts to external loads.

scholarly journals 3D Topology Optimization and Mesh Dependency for Redesigning Locking Compression Plates Aiming to Reduce Stress Shielding

2021 ◽  
Vol 7 (3) ◽  
pp. 339
Author(s):  
A. A. Al-Tamimi
Keyword(s):  
Topology Optimization ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Load Condition ◽  
Metallic Materials ◽  
Metallic Material ◽  
Combined Loads ◽  
Locking Compression Plates ◽  
Strain Energy Minimization ◽  
3D Topology

Current fixation plates for bone fracture treatments are built with biocompatible metallic materials such as stainless steel, titanium, and its alloys (e.g., Ti6Al4V). The stiffness mismatch between the metallic material of the plate and the host bone leads to stress shielding phenomena, bone loss, and healing deficiency. This paper explores the use of three dimensional topology-optimization, based on compliance (i.e., strain energy) minimization, reshaping the design domain of three locking compression plates (four-screw holes, six-screw holes, and eight-screw holes), considering different volume reductions (25, 45, and 75%) and loading conditions (bending, compression, torsion, and combined loads). A finite-element study was also conducted to measure the stiffness of each optimized plate. Thirty-six designs were obtained. Results showed that for a critical value of volume reductions, which depend on the load condition and number of screws, it is possible to obtain designs with lower stiffness, thereby reducing the risk of stress shielding.

scholarly journals A Method for Estimating the Velocity at Which Anaerobic Metabolism Begins in Swimming Fish

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1430
Author(s):  
Feifei He ◽  
Xiaogang Wang ◽  
Yun Li ◽  
Yiqun Hou ◽  
Qiubao Zou ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Crucian Carp ◽  
Anaerobic Metabolism ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Critical Swimming Speed ◽  
Swimming Efficiency ◽  
Rate Of Oxygen Consumption ◽  
Tail Beat

Anaerobic metabolism begins before fish reach their critical swimming speed. Anaerobic metabolism affects the swimming ability of fish, which is not conducive to their upward tracking. The initiation of anaerobic metabolism therefore provides a better predictor of flow barriers than critical swimming speed. To estimate the anaerobic element of metabolism for swimming fish, the respiratory metabolism and swimming performance of adult crucian carp (Carassius auratus, mass = 260.10 ± 7.93, body length = 19.32 ± 0.24) were tested in a closed tank at 20 ± 1 °C. The swimming behavior and rate of oxygen consumption of these carp were recorded at various swimming speeds. Results indicate (1) The critical swimming speed of the crucian carp was 0.85 ± 0.032 m/s (4.40 ± 0.16 BL/s). (2) When a power function was fitted to the data, oxygen consumption, as a function of swimming speed, was determined to be AMR = 131.24 + 461.26Us1.27 (R2 = 0.948, p < 0.001) and the power value (1.27) of Us indicated high swimming efficiency. (3) Increased swimming speed led to increases in the tail beat frequency. (4) Swimming costs were calculated via rate of oxygen consumption and hydrodynamic modeling. Then, the drag coefficient of the crucian carp during swimming was calibrated (0.126–0.140), and the velocity at which anaerobic metabolism was initiated was estimated (0.52 m/s), via the new method described herein. This study adds to our understanding of the metabolic patterns of fish at different swimming speeds.

scholarly journals Swimming Performance of Four Carps on the Yangtze River for Fish Passage Design

2021 ◽  
Vol 13 (3) ◽  
pp. 1575
Author(s):  
Junjun Tan ◽  
Hong Li ◽  
Wentao Guo ◽  
Honglin Tan ◽  
Senfan Ke ◽  
...  
Keyword(s):  
Body Length ◽  
Swimming Speed ◽  
Swimming Performance ◽  
Fish Habitat ◽  
Silver Carp ◽  
Fish Passage ◽  
The Body ◽  
Bighead Carp ◽  
Black Carp ◽  
Burst Swimming

Anthropogenic engineered structures alter the local ecological connectivity of river and survival habitat of native fishes. The swimming performance is critical for establishing fish passage or fish habitat. This study evaluated the swimming performance of four carps (black carp, grass carp, silver carp and bighead carp) with smaller body lengths (1.0–9.0 cm) in a swimming flume. The results showed that the critical and burst swimming speed (m/s) of the four carps increased with the increased body length, and the relative (critical and burst) swimming speed (the critical and burst swimming speed divided by the body length, BL/s) decreases with body length. The critical and burst swimming speed of each species at two individual length groups (1.0–5.0 cm, 5.1–9.0 cm) was significantly different (p < 0.05), and the water velocities in fish passage should be less than the fish burst swimming speed. The results further provided the swimming performance data of juvenile carps and provided technical reference for the construction of fish passage and the restoration of ecological habitat.

Efficient Filtering in Topology Optimization via B-Splines1

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Mingming Wang ◽  
Xiaoping Qian
Keyword(s):  
Topology Optimization ◽  
Three Dimensional ◽  
Processing Unit ◽  
Optimization Scheme ◽  
B Spline ◽  
B Splines ◽  
Central Processing ◽  
Filter Size ◽  
Density Filter ◽  
3D Topology

This paper presents a B-spline based approach for topology optimization of three-dimensional (3D) problems where the density representation is based on B-splines. Compared with the usual density filter in topology optimization, the new B-spline based density representation approach is advantageous in both memory usage and central processing unit (CPU) time. This is achieved through the use of tensor-product form of B-splines. As such, the storage of the filtered density variables is linear with respect to the effective filter size instead of the cubic order as in the usual density filter. Numerical examples of 3D topology optimization of minimal compliance and heat conduction problems are demonstrated. We further reveal that our B-spline based density representation resolves the bottleneck challenge in multiple density per element optimization scheme where the storage of filtering weights had been prohibitively expensive.

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