Abstract
A weakly compressible smoothed particle hydrodynamics (WCSPH) method was developed to model open-channel flow over rough bed. An improved boundary treatment is proposed to quantitatively characterize bed roughness based on the ghost boundary particles (GBPs). In this model, the velocities of GBPs are explicitly calculated by using evolutionary polynomial regression with a multiobjective genetic algorithm. The simulation results show that the proposed boundary treatment can well reflect the influence of wall roughness on the vertical flow structure. A fully developed open channel is established, and its flume length, processing time, and turbulent model are discussed. The mixed-length-based subparticle scale (SPS) turbulence model is adopted to simulate uniform flow in open channel, and this model is compared with the Smagorinsky-based one. For the modified WCSPH model, the results show that the calculated vertical velocity and turbulent shear stress distribution are in good agreement with experimental data and fit better than the calculations obtained from the traditional Smagorinsky-based model.
Highlights
Computational fluid dynamics (CFD) is widely used in hydraulic engineering simulations with good computational efficiency and accuracy
As an important branch of CFD, meshless methods such as smoothed particle hydrodynamics (SPH) method, moving particle semi-implicit (MPS) method, and discrete element method (DEM) have received wide attention due to their ability to consider large deformations of free interface and multiple interfaces without mesh distortion. e SPH method is a widely used Lagrangian meshless method that was originally developed by Gingold and Monaghan [1] and Lucy [2] to solve astrophysics problems and later used in fluid dynamics applications such as fluid-structure interaction [3,4,5], underwater explosion [6, 7], local scour [8, 9], other transport phenomena [10], and related applications [11,12,13]
An in-depth study on the simulation of the open-channel flow over roughness bed based on weakly compressible smoothed particle hydrodynamics (WCSPH) was performed. rough the numerical test, the influence of bed surface roughness on the flow structure was clarified
Summary
Computational fluid dynamics (CFD) is widely used in hydraulic engineering simulations with good computational efficiency and accuracy. Lopez et al [21] proposed that uneven distribution of Lennard-Jones repulsive force exerting on particles near the solid wall can be considered as numerical resistance caused by roughness, Mathematical Problems in Engineering which may suffer from spurious behavior [23]. Chern and Syamsuri [22] used corrugated solid walls to represent rough bed surface resistance, in which different bed boundaries such as triangle-type, trapezoid-type, and sinusoid-type are characterized by discrete particles. These simple approaches are reasonable approximations, the roughness of the bed surface can only be qualitatively expressed in these works, and the effect of the bed roughness on the fluid structure cannot be accurately described
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