A Preliminary Study on the Simulation of Vortex Flow in Pump Intake Based on LBM-VOF-LES Combined Model

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Miao Guo ◽  
Xuelin Tang ◽  
Xiaoqin Li ◽  
Fujun Wang ◽  
Xiaoyan Shi
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Vortex Flow ◽  
Solid Wall ◽  
Flow Patterns ◽  
Vof Method ◽  
Surface Model ◽  
Strain Rate Tensor ◽  
Comparison Of The Results ◽  
Les Model

Abstract In this paper, the lattice Boltzmann method-large eddy simulation (LBM-LES) model was combined with the volume of fluid (VOF) method and used to simulate vortex flow in a typical pump intake. The strain rate tensor in the LES model is locally calculated utilizing nonequilibrium moments based on Chapman–Enskog expansion, and the bounce-back scheme is used for nonslip condition on the solid wall and VOF method for the free surface. The evolution of all kinds of cells on the free surface is based on the mass exchange in the VOF method, i.e., lattice Boltzmann-single phase (LB-SP) free surface model. The introduction of the external force terms is established through adding corresponding expressions on the right of the lattice Boltzmann equation (LBE), and by modifying the velocity. The predicted vortex flow patterns (core location and strength of the vortex) and velocity correlate with the experiments undertaken with the physical model. A comparison of the results demonstrates the feasibility and stability of the model and the numerical method in predicting vortex flows inside pump intakes. The model developed and presented in this paper provides a new analysis method of vortex flow patterns in pump intake from a mesoscopic perspective, enriches the relevant technologies, and makes corresponding contributions to further engineering applications.

An Improved Single-Phase Free-Surface Lattice Boltzmann Model with Surface Tension and Wall Adhesion

2013 ◽  
Vol 300-301 ◽  
pp. 1062-1066
Author(s):  
Yang Yu ◽  
Li Chen ◽  
Jian Hua Lu ◽  
Guo Xiang Hou
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Lattice Boltzmann ◽  
Single Phase ◽  
Lattice Boltzmann Model ◽  
Surface Model ◽  
Two Phase ◽  
Surface Method ◽  
Free Surface Model ◽  
Boltzmann Model

Free-surface model with surface tension and wall adhesion(wetting) is a very efficient technique to simulate two-phase flows with high density and viscosity ratios, such as etching and casting processes. In this paper, a conservative surface tension and wall adhesion model based on lattice Boltzmann single-phase free-surface method is proposed. The effectiveness of the model is demonstrated by simulating the flows induced by wall adhesion and surface tension, and filling processes in a 2D cavity.

A lattice-Boltzmann free surface model for injection moulding of a non-Newtonian fluid

2020 ◽  
Vol 378 (2175) ◽  
pp. 20190407 ◽  
Author(s):  
Daniele Chiappini
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Injection Moulding ◽  
Soft Matter ◽  
Density Ratio ◽  
Acrylonitrile Butadiene Styrene ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Surface Model ◽  
Free Surface Model

The aim of this work is to present a lattice Boltzmann (LB) model devoted to dealing with non-Newtonian free surface flow. The combination of LB solver with a free-surface model allows dealing with multiphase flows where the density ratio in between the two considered phases is so high that the lighter phase can be neglected. For this particular set of multiphase models, the interface between the two phases is numerically reconstructed and transported via a diffusion equation. Moreover, the application of a Carreau approach for viscosity modelling allows the introduction of effects related to shear stress on fluid flow evolution. Two different non-Newtonian silicon-like materials have been considered here, namely the polystyrene and acrylonitrile butadiene styrene. Here, the author, after the mandatory model validation with a reference configuration, presents some applications of injection moulding for two different test-cases: the former is the injection in a labyrinth-like gasket, whereas the latter is the injection in a porous media. This article is part of the theme issue ‘Fluid dynamics, soft matter and complex systems: recent results and new methods’.

scholarly journals Fluid Structure Interaction of 2D Objects through a Coupled KBC-Free Surface Model

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1212
Author(s):  
Daniele Chiappini
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Numerical Data ◽  
Lattice Boltzmann Model ◽  
Surface Model ◽  
Water Tank ◽  
Structure Interaction ◽  
Calm Water ◽  
Free Surface Model ◽  
Boltzmann Model

In this study, the capabilities of a coupled KBC-free surface model to deal with fluid solid interactions with the slamming of rigid obstacles in a calm water tank were analyzed. The results were firstly validated with experimental and numerical data available in literature and, thereafter, some additional analyses was carried out to understand the main parameters’ influence on slamming coefficient. The effect of grid resolution and Reynolds number were firstly considered to choose the proper grid and to present the weak impact of such a non-dimensional number on process evolution. Hence, the influence of Froude number on fluid-dynamics quantities was pointed out considering vertical impacts of both cylindrical, as in the references, and ellipsoidal obstacles. Different formulations of slamming coefficient were used and compared. Results are pretty encouraging and they confirm the effectiveness of lattice Boltzmann model to deal with such a problem. This leaves the door open to additional improvements addressed to the study of free buoyant bodies immersed in a fluid domain.

A LATTICE BOLTZMANN SIMULATION OF THE RHONE RIVER

2013 ◽  
Vol 24 (12) ◽  
pp. 1340008 ◽  
Author(s):  
ANDREA PARMIGIANI ◽  
JONAS LATT ◽  
MOHAMED BEN BEGACEM ◽  
BASTIEN CHOPARD
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Management Strategies ◽  
Three Dimensional ◽  
Parallel Computer ◽  
Water Model ◽  
Surface Model ◽  
Rhône River ◽  
Lattice Boltzmann Simulation ◽  
Rhone River

We present a very detailed numerical simulation of the Rhone river in the Geneva area, using a Lattice Boltzmann (LB) modeling approach. The simulations of water ways are important to better predict and control their behavior when subject to exceptional event or new management strategies. Here, we investigate the current computing limits of using a three-dimensional (3D), free surface model to simulate a high resolution flow over a long section of the river, on a massively parallel computer. We argue that in a near future, computers will be powerful enough to tackle such a simulation. We also compare our results with a two-dimensional (2D) shallow water model to determine in which range a 3D free surface approach provides better insights. Finally, we discuss the advantage of a multi-scale approach for this type of problems.

Effect of Slit Inclusions in Drag Reduction of Flow over Cylinders

2016 ◽  
Vol 846 ◽  
pp. 18-22
Author(s):  
Rohit Bhattacharya ◽  
Abouzar Moshfegh ◽  
Ahmad Jabbarzadeh
Keyword(s):  
Fluid Flow ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Finite Volume ◽  
Lattice Boltzmann ◽  
Circular Cross Section ◽  
Finite Volume Methods ◽  
Turbulent Regime ◽  
Ansys Fluent ◽  
Comparison Of The Results

The flow over bluff bodies is separated compared to the flow over streamlined bodies. The investigation of the fluid flow over a cylinder with a streamwise slit has received little attention in the past, however there is some experimental evidence that show for turbulent regime it reduces the drag coefficient. This work helps in understanding the fluid flow over such cylinders in the laminar regime. As the width of the slit increases the drag coefficient keeps on reducing resulting in a narrower wake as compared to what is expected for flow over a cylinder. In this work we have used two different approaches in modelling a 2D flow for Re=10 to compare the results for CFD using finite volume method (ANSYS FLUENTTM) and Lattice Boltzmann methods. In all cases cylinders of circular cross section have been considered while slit width changing from 10% to 40% of the cylinder diameter. . It will be shown that drag coefficient decreases as the slit ratio increases. The effect of slit size on drag reduction is studied and discussed in detail in the paper. We have also made comparison of the results obtained from Lattice Boltzmann and finite volume methods.

Stability Analysis of Hydropower Stations With Complex Flow Patterns in the Tailrace Tunnel

2013 ◽  
Author(s):  
Jianxu Zhou ◽  
Fulin Cai ◽  
Ming Hu
Keyword(s):  
Free Surface ◽  
Stability Analysis ◽  
Flow Patterns ◽  
Normal Operation ◽  
Complex Flow ◽  
Diversion Tunnel ◽  
Implicit Model ◽  
Special Cases ◽  
Tailrace Tunnel ◽  
Hydropower Stations

For some special tailrace tunnels in the hydropower stations, including the changing top-altitude tailrace tunnel and the tailrace tunnel with downstream reused flat-ceiling diversion tunnel, during normal operation and hydraulic transients, the flow patterns inside are relatively complex mainly including the free-surface pressurized flow and partial free flow if the tail water level is lower than the top elevation of tunnel’s outlet. These complex flow patterns have obvious effect on system’s stability, and can not be simulated accurately by the traditional models. Therefore, a characteristic implicit model is introduced to simulate these complex flow patterns for further stability analysis. In some special cases, the characteristic implicit model also fails to completely simulate the mixed free-surface pressurized flow in the flat-ceiling tailrace tunnel. A new method is presented based on both experimental research and numerical simulation, and then, system’s stability is analyzed by compared with traditional ordinary boundary condition. The results indicate that, with different simulation models for the complex water flow in the tailrace tunnel, system’s dynamic characteristic can be actually revealed with the consideration of the effect of complex flow patterns in the tailrace tunnel on system’s stability and regulation performance.

SIMULATION OF AN AXISYMMETRIC RISING BUBBLE BY A MULTIPLE RELAXATION TIME LATTICE BOLTZMANN METHOD

2009 ◽  
Vol 23 (24) ◽  
pp. 4907-4932 ◽  
Author(s):  
ABBAS FAKHARI ◽  
MOHAMMAD HASSAN RAHIMIAN
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Rise Velocity ◽  
Rising Bubble ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Multiple Relaxation Time ◽  
Bubble Rising ◽  
Boltzmann Method

In this paper, the lattice Boltzmann method is employed to simulate buoyancy-driven motion of a single bubble. First, an axisymmetric bubble motion under buoyancy force in an enclosed duct is investigated for some range of Eötvös number and a wide range of Archimedes and Morton numbers. Numerical results are compared with experimental data and theoretical predictions, and satisfactory agreement is shown. It is seen that increase of Eötvös or Archimedes number increases the rate of deformation of the bubble. At a high enough Archimedes value and low Morton numbers breakup of the bubble is observed. Then, a bubble rising and finally bursting at a free surface is simulated. It is seen that at higher Archimedes numbers the rise velocity of the bubble is greater and the center of the free interface rises further. On the other hand, at high Eötvös values the bubble deforms more and becomes more stretched in the radial direction, which in turn results in lower rise velocity and, hence, lower elevations for the center of the free surface.

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