Author(s): S. C. Chen; S. S. Tfwala

Linked Author(s): Su-Chin Chen, Samkele Tfwala

Keywords: FLOW-3D; XFlow; Fish-bone-type fishway; LES model

Abstract: The advancement of computational power has afforded the resolving of more complex flows in three-dimensional space. Several numerical codes have been developed and to single out which method to use is becoming a more complicated task. In this study two Computational Fluid Dynamic (CFD) platforms, FLOW-3D and XFlow, are presented on 3D turbulent flows in a fishbone type fishway. One of the basic yet most crucial steps in a number of CFD codes is the creation of efficient computational meshes for real world applications. Regardless of the numerical method applied, the mesh quality will have pronounced effects on the final results. Owing to these effects, mesh based (FLOW-3D) and meshless (XFlow) CFD codes are evaluated. FLOW-3D solves the Reynolds averaged Navier-Stokes equations and the continuity equation with the aid of Fractional Area-Volume Obstacle Representation (FAVOR), while XFlow is particle based fully Lagrangian based on the Lattice-Boltzmann method solver. For both codes, turbulence is treated using the Large Eddy Simulation (LES) model. Numerical model accuracy is assessed, comparing the complex flow field in the fishway with fish migration behaviour of fish-swimming species in a laboratory experiment. In addition, computational times and the performance of the models at different discharge rates (0.016 and 0.075), classified as low and medium, respectively, are assessed. Generally, the findings indicated that FLOW-3D better estimated the flow structure, velocity distribution, and flow depth compared to XFlow, while XFlow was relatively faster in terms of computational time despite compromised accuracies.

DOI: https://doi.org/10.15142/T3HH1J

Year: 2018