Modelling flow in a fishway using LABSWE™

Abstract

Fishways are designed to provide a canal for fishes to migrate upstream and downstream when there is a presence of natural or man-made obstructions. In designing the fishway, correct prediction and simulation of the flows play a crucial role. A well designed and constructed fishway will provide a path that allow fish to continue migrating past the obstructions. This paper presents numerical modelling of flows in fishway using Lattice Boltzmann Method for Shallow Water Equations (LABSWE™) in order to demonstrate its simple applicability and accuracy in solving complex flow problems. Lattice Boltzmann Method (LBM) is an alternative numerical method in solving complex fluid flows problems. LBM was found to be efficient and accurate after series complex shallow water problems have been solved. The flow is simulated by using Bhatnagar-Gross-Kook (BGK) collision term. Lattice Boltzmann equation was derived based on shallow water equations. A D2Q9 model was implemented for a more accurate result. The BGK-LBM equations was coded up in MATLAB and the numerical results yield from LBM were then compared with the numerical results solved using Finite Volume Method (FVM). The result comparison was done on velocity vectors, velocity contour and depth contour. From the result comparison, there is good agreement between LBM and FVM which shows that LBM can mimic the flow perfectly. In fact, LBM yield a more detailed and accurate results.