Lattice Boltzmann modeling of shallow water flows over discontinuous beds

Given the complex separation mechanisms of the particulate mixture in a hydrocyclone and the uncertain effects of particle size and shape on separation, this study explored the influence of the maximum projected area of particles on the separation effect as well as single and mixed separations based on CFD–DEM (Computational Fluid Dynamics and Discrete Element Method) coupling and experimental test methods. The results showed that spherical particles flowed out more easily from the downstream as their sizes increased. Furthermore, with the enlargement of maximum projected area, the running space of the particles with the same volume got closer to the upward flow and particles tended to be separated from the upstream. The axial velocity of the combined separation of 60 µm particles and 120 µm particles increased by 25.74% compared with that of single separation of 60 µm particles near the transition section from a cylinder to a cone. The concentration of 60 µm particles near the running space of 120 µm particles increased by 20.73% and those separated from the downstream increased by 4.1%. This study showed the influence of particle size and maximum projected area on the separation effect and the separation mechanism of mixed sand particles in a hydrocyclone, thereby providing a theoretical basis for later studies on the effect of particle size and shape on sedimentation under the cyclone action in a hydrocyclone.

Section: Analysis Of the Following Phenomenon Of Fine Particlesmentioning

confidence: 99%

Effect of Particle Size and Shape on Separation in a Hydrocyclone

Tang

Wang

et al. 2018

“…The LBM has found a wide range of applications in a variety of fields involving shallow water equations. The LBM has been successfully adopted to study shallow water equations of wind-driven ocean circulation [34], intrusion of salt wedges in estuarine zones [35], continuous change in bed elevation [36], wetting-drying problems [37], two immiscible shallow layers of different density [38], and multilayer shallow water equations [39].…”

Section: Lattice Boltzmann Modelmentioning

confidence: 99%

MRT-Lattice Boltzmann Model for Multilayer Shallow Water Flow

Tubbs

Tsai

2019

The objectives of this study are to introduce a multiple-relaxation-time (MRT) lattice Boltzmann model (LBM) to simulate multilayer shallow water flows and to introduce graphics processing unit (GPU) computing to accelerate the lattice Boltzmann model. Using multiple relaxation times in the lattice Boltzmann model has an advantage of handling very low kinematic viscosity without causing a stability problem in the shallow water equations. This study develops a multilayer MRT-LBM to solve the multilayer Saint-Venant equations to obtain horizontal flow velocities in various depths. In the multilayer MRT-LBM, vertical kinematic viscosity forcing is the key term to couple adjacent layers. We implemented the multilayer MRT-LBM to a GPU-based high-performance computing (HPC) architecture. The multilayer MRT-LBM was verified by analytical solutions for cases of wind-driven, density-driven, and combined circulations with non-uniform bathymetry. The results show good speedup and scalability for large problems. Numerical solutions compared well to the analytical solutions. The multilayer MRT-LBM is promising for simulating lateral and vertical distributions of the horizontal velocities in shallow water flow.

“…Therefore, flushing is required to ensure a long economic service life of drip irrigation systems [7]. On the other hand, numerical simulations on shallow water flows and river flushing have been carried out by Peng et al [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Influence of Flushing Velocity and Flushing Frequency on the Service Life of Labyrinth-Channel Emitters

et al. 2018

Dripline flushing is an effective way to relieve emitter clogging and extend the longevity of drip irrigation systems. This laboratory study was conducted at Kunming University of Science and Technology to evaluate the effect of three targeted flushing velocities (0.3, 0.6, and 0.9 m/s) and four flushing frequencies (no flushing, flushing daily, and flushing every three or five days) on the emitter’s service life and the particle size distribution of the sediment discharged from emitters and trapped in an emitter channel. The gradation of particle size was analyzed by a laser particle size analyzer. The experiment results suggested that flushing velocity and flushing frequency had a significant effect on the service life of emitters, and the emitter’s service life was extended by 30.40% on average under nine different flushing treatments. Flushing can effectively reduce the accumulation of sediments in the dripline and decrease the probability of coarse particles flowing into emitters and fine particles aggregating and cementing in the labyrinth channel, thus relieving the emitter clogging. Therefore, dripline flushing can effectively slow down clogging in muddy water drip irrigation system. The recommended flushing velocity should be set at 0.6 m/s, and the flushing intervals should be shortened.