Mixing model with multiparticle interactions for Lagrangian simulations of turbulent mixing
Abstract
We report on the numerical study of the mixing volume model (MVM) for molecular diffusion in Lagrangian simulations of turbulent mixing problems. The MVM is based on the multiparticle interaction in a finite volume (mixing volume). A priori test of the MVM, based on the direct numerical simulations of planar jets, is conducted in the turbulent region and the interfacial layer between the turbulent and nonturbulent fluids. The results show that the MVM predicts well the mean effects of the molecular diffusion under various numerical and flow parameters. The number of the mixing particles should be large for predicting a value of the molecular diffusion term positively correlated to the exact value. The size of the mixing volume relative to the Kolmogorov scale η is important in the performance of the MVM. The scalar transfer across the turbulent/nonturbulent interface is well captured by the MVM especially with the small mixing volume. Furthermore, the MVM with multiple mixing particles is tested in the hybrid implicit largeeddysimulation/Lagrangianparticlesimulation (LES–LPS) of the planar jet with the characteristic length of the mixing volume of O(100η). Despite the large mixing volume, the MVM works well and decays the scalar variance in a rate close to themore »
 Authors:
 Department of Aerospace Engineering, Nagoya University, Nagoya (Japan)
 Publication Date:
 OSTI Identifier:
 22598910
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Fluids; Journal Volume: 28; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 42 ENGINEERING; DIFFUSION; FLOW MODELS; FLUIDS; GRIDS; JETS; LAGRANGIAN FUNCTION; LARGEEDDY SIMULATION; LAYERS; LENGTH; MIXING; NUMERICAL ANALYSIS; PARTICLE INTERACTIONS; PARTICLES; PERFORMANCE; SCALAR FIELDS; SCALARS; STATISTICS; TURBULENCE
Citation Formats
Watanabe, T., Email: watanabe.tomoaki@c.nagoyau.jp, and Nagata, K. Mixing model with multiparticle interactions for Lagrangian simulations of turbulent mixing. United States: N. p., 2016.
Web. doi:10.1063/1.4960770.
Watanabe, T., Email: watanabe.tomoaki@c.nagoyau.jp, & Nagata, K. Mixing model with multiparticle interactions for Lagrangian simulations of turbulent mixing. United States. doi:10.1063/1.4960770.
Watanabe, T., Email: watanabe.tomoaki@c.nagoyau.jp, and Nagata, K. 2016.
"Mixing model with multiparticle interactions for Lagrangian simulations of turbulent mixing". United States.
doi:10.1063/1.4960770.
@article{osti_22598910,
title = {Mixing model with multiparticle interactions for Lagrangian simulations of turbulent mixing},
author = {Watanabe, T., Email: watanabe.tomoaki@c.nagoyau.jp and Nagata, K.},
abstractNote = {We report on the numerical study of the mixing volume model (MVM) for molecular diffusion in Lagrangian simulations of turbulent mixing problems. The MVM is based on the multiparticle interaction in a finite volume (mixing volume). A priori test of the MVM, based on the direct numerical simulations of planar jets, is conducted in the turbulent region and the interfacial layer between the turbulent and nonturbulent fluids. The results show that the MVM predicts well the mean effects of the molecular diffusion under various numerical and flow parameters. The number of the mixing particles should be large for predicting a value of the molecular diffusion term positively correlated to the exact value. The size of the mixing volume relative to the Kolmogorov scale η is important in the performance of the MVM. The scalar transfer across the turbulent/nonturbulent interface is well captured by the MVM especially with the small mixing volume. Furthermore, the MVM with multiple mixing particles is tested in the hybrid implicit largeeddysimulation/Lagrangianparticlesimulation (LES–LPS) of the planar jet with the characteristic length of the mixing volume of O(100η). Despite the large mixing volume, the MVM works well and decays the scalar variance in a rate close to the reference LES. The statistics in the LPS are very robust to the number of the particles used in the simulations and the computational grid size of the LES. Both in the turbulent core region and the intermittent region, the LPS predicts a scalar field well correlated to the LES.},
doi = {10.1063/1.4960770},
journal = {Physics of Fluids},
number = 8,
volume = 28,
place = {United States},
year = 2016,
month = 8
}

Verification of EulerianEulerian and EulerianLagrangian simulations for turbulent fluidparticle flows
Here, we present a verification study of three simulation techniques for fluid–particle flows, including an Euler–Lagrange approach (EL) inspired by Jackson's seminal work on fluidized particles, a quadrature–based moment method based on the anisotropic Gaussian closure (AG), and the traditional twofluid model. We perform simulations of two problems: particles in frozen homogeneous isotropic turbulence (HIT) and clusterinduced turbulence (CIT). For verification, we evaluate various techniques for extracting statistics from EL and study the convergence properties of the three methods under grid refinement. The convergence is found to depend on the simulation method and on the problem, with CIT simulations posingmore » 
Guidelines for the formulation of Lagrangian stochastic models for particle simulations of singlephase and dispersed twophase turbulent flows
In this paper, we establish a set of criteria which are applied to discuss various formulations under which Lagrangian stochastic models can be found. These models are used for the simulation of fluid particles in singlephase turbulence as well as for the fluid seen by discrete particles in dispersed turbulent twophase flows. The purpose of the present work is to provide guidelines, useful for experts and nonexperts alike, which are shown to be helpful to clarify issues related to the form of Lagrangian stochastic models. A central issue is to put forward reliable requirements which must be met by Lagrangianmore » 
A priori and a posteriori investigations for developing large eddy simulations of multispecies turbulent mixing under highpressure conditions
A Direct Numerical Simulation (DNS) database was created representing mixing of species under highpressure conditions. The configuration considered is that of a temporally evolving mixing layer. The database was examined and analyzed for the purpose of modeling some of the unclosed terms that appear in the Large Eddy Simulation (LES) equations. Several metrics are used to understand the LES modeling requirements. First, a statistical analysis of the DNSdatabase largescale flow structures was performed to provide a metric for probing the accuracy of the proposed LES models as the flow fields obtained from accurate LESs should contain structures of morphology statisticallymore »