Sediment transport in turbulent flows with the lattice Boltzmann method

2018 ◽  
Vol 172 ◽  
pp. 340-351 ◽  
Author(s):  
Helen E. Morrison ◽  
Alfred Leder
Keyword(s):  
Sediment Transport ◽  
Lattice Boltzmann Method ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Boltzmann Method

Direct Transmission Loss Calculation of Simplified Muffler Configurations Using a Lattice-Boltzmann Method

2013 ◽  
Author(s):  
Adrien Mann ◽  
Franck Pérot
Keyword(s):  
Lattice Boltzmann Method ◽  
Turbulent Flows ◽  
Spatial Resolution ◽  
Lattice Boltzmann ◽  
Transmission Loss ◽  
Fan Noise ◽  
Wind Noise ◽  
Simulation Domain ◽  
Flow Induced Noise ◽  
Boltzmann Method

Lattice-Boltzmann Method (LBM) is broadly used for the simulation of aeroacoustics problems. This time-domain CFD/CAA approach is transient, explicit and compressible and offers an accurate and efficient solution to simultaneously resolve turbulent flows and their corresponding flow-induced noise radiation. Some examples of applications are ground transportation wind-noise problems, buffeting, Heating, Ventilation, and Air Conditioning (HVAC), fan noise, etc. As shown in previous studies, LBM can also be used to accurately handle linear acoustics problems if the source of noise is not a flow but a simple acoustic source. This set of capabilities makes LBM a suitable candidate for evaluating the acoustics performances of exhaust systems and mufflers. Compared to other traditional acoustics methods, LBM presents the advantage to skip tedious volume meshing operations since the mesh generation is fully automatic. Furthermore, considering that all geometrical details are included in the simulation domain and that LBM is explicit, high frequencies mechanisms up to 10–20 kHz can be captured. The upper frequency limit is indeed solely driven by the spatial resolution used to discretize the system. In this paper, three academic 3-D geometries representative of production muffler systems are studied. Transmission Loss (TL) measurements are performed on three configurations and these experiments are reproduced numerically with LBM. The experimental setup is described in a first part and the numerical details are given in a second part and third part. In particular, the method used to calculate the TL in the simulation and the convergence of the results with respect to the spatial resolution are shown. In a third part, the simulations are compared to the TL measurements and a numerical investigation of the effect of geometry details on the simulated results is proposed. This study highlights the sensitivity of acoustics measurements to geometry details.

Consistent subgrid scale modelling for lattice Boltzmann methods

2012 ◽  
Vol 700 ◽  
pp. 514-542 ◽  
Author(s):  
Orestis Malaspinas ◽  
Pierre Sagaut
Keyword(s):  
Lattice Boltzmann Method ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Stokes Equations ◽  
Mixing Layer ◽  
Velocity Distribution Function ◽  
Theoretical Point ◽  
Subgrid Scale ◽  
Hermite Expansion ◽  
Boltzmann Method

AbstractThe lattice Boltzmann method has become a widely used tool for the numerical simulation of fluid flows and in particular of turbulent flows. In this frame the inclusion of subgrid scale closures is of crucial importance and is not completely understood from the theoretical point of view. Here, we propose a consistent way of introducing subgrid closures in the BGK Boltzmann equation for large eddy simulations of turbulent flows. Based on the Hermite expansion of the velocity distribution function, we construct a hierarchy of subgrid scale terms, which are similar to those obtained for the Navier–Stokes equations, and discuss their inclusion in the lattice Boltzmann method scheme. A link between our approach and the standard way on including eddy viscosity models in the lattice Boltzmann method is established. It is shown that the use of a single modified scalar relaxation time to account for subgrid viscosity effects is not consistent in the compressible case. Finally, we validate the approach in the weakly compressible case by simulating the time developing mixing layer and comparing with experimental results and direct numerical simulations.

Two-Dimensional Simulations of Turbulent Flow Past a Row of Cylinders using Lattice Boltzmann Method

2017 ◽  
Vol 14 (01) ◽  
pp. 1750002 ◽  
Author(s):  
Yi-Kun Wei ◽  
Xu-Qu Hu
Keyword(s):  
Lattice Boltzmann Method ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Passive Scalar ◽  
Two Dimensional ◽  
Flow Past ◽  
High Reynolds ◽  
An Array Of Cylinders ◽  
Boltzmann Method

Two-dimensional simulations of channel flow past an array of cylinders are carried out at high Reynolds numbers. Considering the thickness fluctuating effect on the equation of motion, a modified lattice Boltzmann method (LBM) is proposed. Special attention is paid to investigate the thickness fluctuations and vortex shedding mechanisms between 11 cylinders. Results for the velocity and vorticity differences are provided, as well as for the energy density and enstrophy spectra. The numerical results coincide very well with some published experimental data that was obtained by turbulent soap films. The spectra extracted from the velocity and vorticity fields are displayed from simulations, along with the thickness fluctuation spectrum H(k). Our results show that the statistics of thickness fluctuations resemble closely those of a passive scalar in turbulent flows.

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