Numerical Investigation on Three-Dimensional Fishway Hydrodynamics and Fish Passage Energetics
Date Issued
2007
Date
2007
Author(s)
Gu, Ke-Shin
DOI
zh-TW
Abstract
本研究主要目的為研析上溯魚種-駝背大麻哈 (pink salmon) 在池堰式與豎孔式魚道流場中，採不同之上溯運動方式、不同之上溯路徑，其能量消耗之比較。研究之魚道流場使用三維度標準 紊流模式，搭配體積分率法來模擬具自由液面之二相流邊界條件，並計算魚體在流場中逆流上溯所遭受之阻力與能量之損耗。本研究先以Ead (2004) 與Purertas等 (2004) 所試驗之魚道縮尺模型，來驗證五種不同魚道設計 (三種池堰式、兩種豎孔式) ，流經堰體與隔板之流況與水位，繼而規劃真實尺寸之模式應用案例。本研究藉由不同上溯路徑與上溯運動方式，透過魚體於水中力能之分析研究，並改良Weihs在2002年提出的跳躍前進之耗能計算方式，將跳躍運動應用至魚道流場內，以進行各種上溯案例間能量損耗之比較。由研究結果顯示，池堰式魚道模式應用案例中，同一魚種之最省能之路徑，為魚體採跳躍上溯且近液面之路徑；而豎孔式魚道模式應用案例則是以通過短隔板後渦流區為最省能之路徑。
The main purpose of this study is to discuss the trajectories of the migrating fish (pink salmon) tracing back to upstream through pool-and-weir fishway and vertical-slot fishway, and compares the energetics for various migrating motions. A 3-D standard turbulent model together with the volume of fraction (VOF) method is used to solve fishway hydrodynamics. The simulated flow-field results are next employed to estimate the force and energy acting on the fish body.The Numerical model is firstly verified by the reduced-scale experimental measurement of Ead et al.(2004) and Purertas et al.(2004). The numerical results are in good agreement with the experimental data in terms of water depths, flow velocities, and free surface profiles. A series of numerical scenario simulations are further conducted to simulate real-size fishways hydrodynamics. For the cases that fish is migrating in the pool-and-weir fishway, we modify the equations of dolphin dynamics (Weihs, 2000) to analyze the energy losses for various migrating motions. The simulated results show that the most economic fish energy passage in the pool-and-weir fishways is to take jump motion and to go through near the water surface, whereas the most economic fish energy passage in the vertical-slot fishway is to take the way which goes through the eddy behind the short slot.
Subjects
池堰式魚道
豎孔式魚道
紊流模式
自由液面
體積分率法
Pool-and-weir fishway
Vertical-slot fishway
turbulent model
Volume of fraction method (VOF)
Free surface
Type
thesis
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