scholarly journals Mixing in Turbulent Flows: An Overview of Physics and Modelling

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1379
Author(s):  
Jacek Pozorski ◽  
Marta Wacławczyk
Keyword(s):  
Density Function ◽  
Turbulent Flows ◽  
Chemical Species ◽  
Scalar Fields ◽  
Industrial Applications ◽  
Mixing Models ◽  
Computing Technology ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Large Eddy

Turbulent flows featuring additional scalar fields, such as chemical species or temperature, are common in environmental and industrial applications. Their physics is complex because of a broad range of scales involved; hence, efficient computational approaches remain a challenge. In this paper, we present an overview of such flows (with no particular emphasis on combustion, however) and we recall the major types of micro-mixing models developed within the statistical approaches to turbulence (the probability density function approach) as well as in the large-eddy simulation context (the filtered density function). We also report on some trends in algorithm development with respect to the recent progress in computing technology.

Application of Scalar Filtered Density Function to Turbulent Flows Under Supercritical Condition

2021 ◽  
pp. 1-25
Author(s):  
Reza Sheikhi ◽  
Fatemeh Hadi
Keyword(s):  
Density Function ◽  
Turbulent Flows ◽  
Mixing Layer ◽  
Supercritical Condition ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Fluid Behavior ◽  
Real Fluid ◽  
Large Eddy ◽  
Robinson Equation

Abstract The scalar filtered density function (FDF) methodology is extended and employed for large eddy simulation (LES) of turbulent flows under supercritical condition. To describe real-fluid behavior, the extended methodology incorporates the generalized heat and mass diffusion models along with real fluid thermodynamic relations which are derived using the cubic Peng-Robinson equation of state. These models are implemented within the stochastic differential equations comprising the scalar FDF transport. Simulations are conducted of a temporally developing mixing layer under supercritical condition and the results are assessed by comparing with data generated by direct numerical simulation (DNS) of the same layer. The consistency of the proposed FDF methodology is assessed. The LES-FDF predictions are shown to agree favorably with the DNS data and exhibit several key features pertaining to supercritical turbulent flows.

Velocity-scalar filtered density function for large eddy simulation of turbulent flows

2003 ◽  
Vol 15 (8) ◽  
pp. 2321-2337 ◽  
Author(s):  
M. R. H. Sheikhi ◽  
T. G. Drozda ◽  
P. Givi ◽  
S. B. Pope
Keyword(s):  
Large Eddy Simulation ◽  
Density Function ◽  
Turbulent Flows ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Large Eddy

Entropy Filtered Density Function for Large Eddy Simulation of Turbulent Flows

AIAA Journal ◽  
2015 ◽  
Vol 53 (9) ◽  
pp. 2571-2587 ◽  
Author(s):  
M. R. H. Sheikhi ◽  
M. Safari ◽  
F. Hadi
Keyword(s):  
Large Eddy Simulation ◽  
Density Function ◽  
Turbulent Flows ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Large Eddy

Velocity filtered density function for large eddy simulation of turbulent flows

2002 ◽  
Vol 14 (3) ◽  
pp. 1196-1213 ◽  
Author(s):  
L. Y. M. Gicquel ◽  
P. Givi ◽  
F. A. Jaberi ◽  
S. B. Pope
Keyword(s):  
Large Eddy Simulation ◽  
Density Function ◽  
Turbulent Flows ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Large Eddy

Analysis of Local Entropy Generation via Large Eddy Simulation of Turbulent Flows

2010 ◽  
Author(s):  
M. Reza H. Sheikhi ◽  
Mehdi Safari ◽  
Hameed Metghalchi
Keyword(s):  
Large Eddy Simulation ◽  
Transport Equation ◽  
Turbulent Flows ◽  
Entropy Generation ◽  
Local Entropy ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Entropy Transport ◽  
Large Eddy ◽  
Local Entropy Generation

A novel methodology is developed for local entropy generation analysis of turbulent flows using large eddy simulation (LES). The entropy transport equation is introduced in LES. The filtered form of this equation includes the unclosed subgrid scale entropy generation effects. The closure is based on the filtered density function (FDF) methodology, extended to include the transport of entropy. An exact transport equation is derived for the FDF. The unclosed terms in this equation is modeled by considering a system of stochastic differential equations. LES/FDF is employed to simulate a turbulent shear layer involving transport of mass, energy and entropy. The local entropy generation effects are obtained from the FDF and analyzed. It is shown that the dominant contribution to entropy generation in this flow is due to the combined effects of energy transfer by heat interaction and mass diffusion.

Self-conditioned fields for large-eddy simulations of turbulent flows

2010 ◽  
Vol 652 ◽  
pp. 139-169 ◽  
Author(s):  
STEPHEN B. POPE
Keyword(s):  
Velocity Field ◽  
Density Function ◽  
Turbulent Flows ◽  
Evolution Equations ◽  
Stokes Equations ◽  
The Self ◽  
Mean Velocity ◽  
Full Account ◽  
Filtered Density Function ◽  
Large Eddy

An alternative foundation is developed for the large-eddy simulation (LES) of turbulent flows. It is based on ‘self-conditioned fields’, for example, the mean velocity field conditional on a discrete representation of the filtered velocity field. It is shown that the self-conditioned velocity field minimizes the residual kinetic energy, and that, with the ideal model, the method yields the correct one-time behaviour as determined by the Navier–Stokes equations. The approach is extended to the self-conditioned probability density function (PDF) of compositions. Compared to LES formulations based on the filtered velocity and the filtered density function, the self-conditioned field approach has several advantages: for laminar flow, and in the direct-numerical-simulation limit, the residual fluctuations are zero or exponentially small; full account is taken of the probability distribution of turbulent fields; there are no commutation issues; and there are no issues with filtering at walls, where the self-conditioned velocity is zero. The exact evolution equations for the self-conditioned velocity and composition PDF are derived. Basic models are presented, and the development of improved models is discussed.

Large Eddy Simulation for Local Entropy Generation Analysis of Turbulent Flows

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
M. R. H. Sheikhi ◽  
Mehdi Safari ◽  
Hameed Metghalchi
Keyword(s):  
Large Eddy Simulation ◽  
Transport Equation ◽  
Turbulent Flows ◽  
Entropy Generation ◽  
Local Entropy ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Entropy Transport ◽  
Large Eddy ◽  
Local Entropy Generation

A new methodology is developed for local entropy generation analysis of turbulent flows using large eddy simulation (LES). The entropy transport equation is considered in LES and is solved along with continuity, momentum, and scalar transport equations. The filtered entropy equation includes several unclosed source terms that contribute to entropy generation. The closure is based on the filtered density function (FDF) methodology, extended to include the transport of entropy. An exact transport equation is derived for the FDF. The unclosed terms in this equation are modeled by considering a system of stochastic differential equations (SDEs). The methodology is employed for LES of a turbulent shear layer involving transport of passive chemical species, energy, and entropy. The local entropy generation effects are obtained from the FDF and are analyzed. It is shown that the dominant contribution to entropy generation in this flow is due to combined effects of energy transfer by heat and mass diffusion. The FDF results are assessed by comparing with those obtained by direct numerical simulation (DNS) of the same layer. The FDF predictions show favorable agreements with the DNS data.

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