Direct Numerical Simulation of Multiple Particles Sedimentation at an Intermediate Reynolds Number

AbstractIn this work the previously developed Lattice Boltzmann-Direct Forcing/ Fictitious Domain (LB-DF/FD) method is adopted to simulate the sedimentation of eight circular particles under gravity at an intermediate Reynolds number of about 248. The particle clustering and the resulting Drafting-Kissing-Tumbling (DKT) motion which takes place for the first time are explored. The effects of initial particle-particle gap on the DKT motion are found significant. In addition, the trajectories of particles are presented under different initial particle-particle gaps, which display totally three kinds of falling patterns provided that no DKT motion takes place, i.e. the concave-down shape, the shape of letter “M” and “in-line” shape. Furthermore, the lateral and vertical hydrodynamic forces on the particles are investigated. It has been found that the value of Strouhal number for all particles is the same which is about 0.157 when initial particle-particle gap is relatively large. The wall effects on falling patterns and particle expansions are examined in the final.

Download Full-text

The Turbulent Flow over the BARC Rectangular Cylinder: A DNS Study

Flow Turbulence and Combustion ◽

10.1007/s10494-021-00254-1 ◽

2021 ◽

Author(s):

Alessandro Chiarini ◽

Maurizio Quadrio

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Direct Numerical Simulation ◽

Finite Differences ◽

Turbulence Models ◽

Fine Tuning ◽

Rectangular Cylinder ◽

Budget Equation ◽

Complete Set ◽

First Time

AbstractA direct numerical simulation (DNS) of the incompressible flow around a rectangular cylinder with chord-to-thickness ratio 5:1 (also known as the BARC benchmark) is presented. The work replicates the first DNS of this kind recently presented by Cimarelli et al. (J Wind Eng Ind Aerodyn 174:39–495, 2018), and intends to contribute to a solid numerical benchmark, albeit at a relatively low value of the Reynolds number. The study differentiates from previous work by using an in-house finite-differences solver instead of the finite-volumes toolbox OpenFOAM, and by employing finer spatial discretization and longer temporal average. The main features of the flow are described, and quantitative differences with the existing results are highlighted. The complete set of terms appearing in the budget equation for the components of the Reynolds stress tensor is provided for the first time. The different regions of the flow where production, redistribution and dissipation of each component take place are identified, and the anisotropic and inhomogeneous nature of the flow is discussed. Such information is valuable for the verification and fine-tuning of turbulence models in this complex separating and reattaching flow.

Download Full-text

Toward Direct Numerical Simulation of Aeroacoustic Field Around Airfoil Using Multi-Scale Lattice Boltzmann Method

Volume 1A, Symposia: Advances in Fluids Engineering Education; Advances in Numerical Modeling for Turbomachinery Flow Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, and Hybrid RANS/LES Methods ◽

10.1115/fedsm2013-16526 ◽

2013 ◽

Cited By ~ 3

Author(s):

K. Kusano ◽

K. Yamada ◽

M. Furukawa

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Mach Number ◽

Direct Numerical Simulation ◽

Lattice Boltzmann Method ◽

Lattice Boltzmann ◽

Low Mach Number ◽

Multi Scale ◽

Moderate Reynolds Number ◽

Boltzmann Method

Lattice Boltzmann method (LBM) has a potential to simulate airfoil self-noise with low Mach number flow including turbulent flow and aerodynamic feedback loops. In this study, the computational techniques concerning LBM were developed toward direct numerical simulation of aeroacoustic fields with low Mach number. For applications of multi-scale phenomena such as flow and acoustic fields, multi-scale model was introduced, which enables to use locally refined grids. The grids were efficiently arranged using the Building-Cube Method (BCM) by dividing the computational domain into multiple blocks with various grid sizes. Furthermore, the zonal DNS and LES approach was adopted to suppress the numerical instability in the region of coarse grids. The grid dependency of the results provided by the present numerical method was investigated by two-dimensional simulations of flow fields around a NACA0012 airfoil using four different grids. Furthermore, a three-dimensional simulation of flow around a NACA0018 airfoil with moderate Reynolds number was conducted. The computational results were compared and have a good agreement with the experimental ones. The present method can simulate flow around airfoil with moderate Reynolds number involving the laminar-to-turbulent transition.

Download Full-text

Direct Numerical Simulation of Turbulent Flow and Aeroacoustic Fields Around an Airfoil Using Lattice Boltzmann Method

Volume 1A, Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES and Hybrid RANS/LES Methods; Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Active Fluid Dynamics and Flow Control — Theory, Experiments and Implementation ◽

10.1115/fedsm2016-7585 ◽

2016 ◽

Author(s):

Kazuya Kusano ◽

Kazutoyo Yamada ◽

Masato Furukawa ◽

Kil-Ju Moon

Keyword(s):

Numerical Simulation ◽

Boundary Layer ◽

Reynolds Number ◽

Direct Numerical Simulation ◽

Lattice Boltzmann Method ◽

Lattice Boltzmann ◽

Separated Flow ◽

Broadband Noise ◽

Suction Surface ◽

Boltzmann Method

The paper presents a result of the direct numerical simulation with the lattice Boltzmann method which was conducted for quantitative prediction of turbulent broadband noise. For better prediction of broadband noise with high frequency, which is generally generated in high Reynolds number flows, not only high grid resolution is required for a flow simulation to capture very small eddies of the sound source inside the turbulent boundary layer, but also the computation of acoustic field is often needed. In such case, the direct simulation of flow field and acoustic field is straightforward and effective. In this study, the direct simulation with the lattice Boltzmann method was conducted for a flow around the NACA0012 airfoil with the Reynolds number of two hundred thousand. In order to efficiently simulate this high Reynolds number flow with the LBM, the multi-scale approach was introduced in conjunction with the Building-cube method, while keeping the advantage of the LBM with the Cartesian mesh. At the condition with angle-of-attack of 9 degrees, a laminar separation bubble arises on the suction surface near the leading-edge and the suction boundary layer downstream of it is turbulent due to the separated-flow transition. As a result, turbulent broadband noise is generated from the boundary layer over the airfoil with the separated-flow transition. In the paper, as for prediction of such broadband noise, the computed frequency spectrum of far-field sound is validated to agree with the experimental result. In addition, through the detailed analyses of turbulent properties of the turbulent boundary layer on the suction surface, the validity of the present direct numerical simulation is demonstrated.

Download Full-text

Improved low-Reynolds-number k-epsilon-tilde model based on direct numerical simulation data

AIAA Journal ◽

10.2514/3.13775 ◽

1998 ◽

Vol 36 ◽

pp. 38-43

Author(s):

C. B. Hwang ◽

C. A. Lin

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Direct Numerical Simulation ◽

Low Reynolds Number ◽

Simulation Data ◽

Direct Numerical Simulation Data ◽

Model Based ◽

Low Reynolds

Download Full-text

Direct numerical simulation of plane Couette flow at the transitional Reynolds number.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.52.3460 ◽

1986 ◽

Vol 52 (482) ◽

pp. 3460-3468

Author(s):

Yutaka MIYAKE ◽

Takeo KAJISHIMA ◽

Shigeru OBANA

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Direct Numerical Simulation ◽

Couette Flow ◽

Plane Couette Flow

Download Full-text

Effects of Turbulent Reynolds Number on the Performance of Algebraic Flame Surface Density Models for Large Eddy Simulation in the Thin Reaction Zones Regime: A Direct Numerical Simulation Analysis

Journal of Combustion ◽

10.1155/2012/353257 ◽

2012 ◽

Vol 2012 ◽

pp. 1-13 ◽

Cited By ~ 6

Author(s):

Mohit Katragadda ◽

Nilanjan Chakraborty ◽

R. S. Cant

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Fractal Dimension ◽

Direct Numerical Simulation ◽

Surface Density ◽

Flame Surface ◽

Algebraic Models ◽

Flame Surface Density ◽

Turbulent Reynolds Number ◽

Reaction Zones

A direct numerical simulation (DNS) database of freely propagating statistically planar turbulent premixed flames with a range of different turbulent Reynolds numbers has been used to assess the performance of algebraic flame surface density (FSD) models based on a fractal representation of the flame wrinkling factor. The turbulent Reynolds number Rethas been varied by modifying the Karlovitz number Ka and the Damköhler number Da independently of each other in such a way that the flames remain within the thin reaction zones regime. It has been found that the turbulent Reynolds number and the Karlovitz number both have a significant influence on the fractal dimension, which is found to increase with increasing Retand Ka before reaching an asymptotic value for large values of Retand Ka. A parameterisation of the fractal dimension is presented in which the effects of the Reynolds and the Karlovitz numbers are explicitly taken into account. By contrast, the inner cut-off scale normalised by the Zel’dovich flame thicknessηi/δzdoes not exhibit any significant dependence on Retfor the cases considered here. The performance of several algebraic FSD models has been assessed based on various criteria. Most of the algebraic models show a deterioration in performance with increasing the LES filter width.

Download Full-text

Study of the Mixed Convection in a Horizontal Channel Heated from below

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.789-790.398 ◽

2015 ◽

Vol 789-790 ◽

pp. 398-402

Author(s):

N. Mahfoud Sahraoui ◽

Samir Houat ◽

Nawal Saidi

Keyword(s):

Numerical Simulation ◽

Reynolds Number ◽

Mixed Convection ◽

Lattice Boltzmann ◽

Thermal Field ◽

Lattice Boltzmann Model ◽

Horizontal Channel ◽

Comparison Of The Results ◽

Stretching Ratio ◽

Boltzmann Model

In this work, a contribution to the modeling and numerical simulation of mixed convection in a horizontal channel heated from below is presented. The lattice Boltzmann model with double thermal populations (TLBM) is used with the D2Q9 model for the dynamic field and D2Q5 for the thermal field. A comparison of the results obtained by the lattice Boltzmann model with those of the literature is presented for an area stretching ratio B = H / L = 20, a Reynolds number Re = 10, Rayleigh Ra = 104 and Peclet number Pe = 20/3. The streamlines and isotherms are presented for different periods of flow.

Download Full-text