| Author: | Yu, Antong |
| Title: | On the hydrodynamic performance of metachronal paddling |
| Degree: | M.Sc. |
| Year: | 2022 |
| Subject: | Malacostraca -- Locomotion Hydrodynamics Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Mechanical Engineering |
| Pages: | iii, 90 pages : color illustrations |
| Language: | English |
| Abstract: | Aquatic crustaceans, such as shrimps and krill, adopt a drag-based propulsion scheme for locomotion, where the motion of one appendage lags behind or advances ahead of that of its neighbor forming metachronal paddling. This locomotion strategy has inspired many studies, most of which focused on exploring the propulsion performance of a fixed model with multiple appendages that were commonly modelled as straight segments. Although interesting and promising, some important questions remain elusive. For instance, in nature, each appendage consists of both upper and lower parts which can move independently during locomotion, but rare studies have considered this factor. As such, whether and how it affects the propulsion performance of the paddling is unclear. Additionally, in most cases, the model is fixed in space, whereas the propulsion performance of a model which can move freely has not been fully explored. This research work aims to bridge these gaps. In particular, a krill/shrimp is modelled as a two-dimensional model which contains one or five limbs and is able to move freely in the horizontal direction. Each limb consists of upper and lower parts, while their motions are prescribed according to those of their counterparts observed in nature. These problems are solved with an in-house numerical framework based on the immersed boundary-lattice Boltzmann method (IBLBM). The results demonstrate that the independent movements of the upper and lower parts play an important role in the dynamics of a single-limb model. The orientations, stroke amplitudes and phase differences of the two parts determine the kinematic symmetric properties of the whole limb, hence its propulsion performance. By contrast, the phase difference between two adjacent limbs is the dominant factor for the hydrodynamic performance of the five-limb model, that affects the extent to which the flow directed by one limb undergoing power stroke is obstructed by its neighbors. Furthermore, the influences of the limb kinematics and the Reynolds number are also revealed. It is believed that the findings and analysis in this study can provide some insights into the understanding of the hydrodynamic performance of metachronal paddling as well as some guidelines for designing bio-inspired autonomous underwater vehicles (AUV) driven by metachronal paddles. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 6882.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 9.8 MB | Adobe PDF | View/Open |
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