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A methodology termed entropy filtered density function (En-FDF) is developed to account for entropy transport in large eddy simulation of turbulent flows. The filtered entropy transport equation includes several unclosed terms which are the subgrid scale entropy flux and the filtered entropy generation resulting from irreversibilities in heat conduction, mass diffusion, chemical reaction and viscous dissipation. The En-FDF contains the complete statistical information about entropy, velocity, scalar and turbulent frequency fields and thus, provides closure for all the unclosed terms in the filtered transport equations. An exact transport equation is derived for the En-FDF which contains the effects of convection along with chemical reaction and its associated entropy generation in closed forms. The En-FDF transport is modeled by a set of stochastic differential equations. The numerical solution procedure is based on a hybrid finite difference/Monte Carlo method in which the large eddy simulation filtered transport equations are solved by the finite difference, and the stochastic differential equations are solved by a Lagrangian Monte Carlo procedure. This methodology is applied for large eddy simulation of a turbulent shear layer involving transport of passive scalars and predictions are compared against the data generated by direct numerical simulation. The En-FDF predictions show favorable agreement with the direct numerical simulation data.
M. R. H. Sheikhi; M. Safari; F. Hadi. Entropy Filtered Density Function for Large Eddy Simulation of Turbulent Flows. AIAA Journal 2015, 53, 2571 -2587.
AMA StyleM. R. H. Sheikhi, M. Safari, F. Hadi. Entropy Filtered Density Function for Large Eddy Simulation of Turbulent Flows. AIAA Journal. 2015; 53 (9):2571-2587.
Chicago/Turabian StyleM. R. H. Sheikhi; M. Safari; F. Hadi. 2015. "Entropy Filtered Density Function for Large Eddy Simulation of Turbulent Flows." AIAA Journal 53, no. 9: 2571-2587.
An overview is presented of the recent developments in the application of large eddy simulation (LES) for prediction and analysis of local entropy generation in turbulent reacting flows. A challenging issue in such LES is subgrid-scale (SGS) modeling of filtered entropy generation terms. An effective closure strategy, recently developed, is based on the filtered density function (FDF) methodology with inclusion of entropy variations. This methodology, titled entropy FDF (En-FDF), is the main focus of this article. The En-FDF has been introduced as the joint velocity-scalar-turbulent frequency-entropy FDF and the marginal scalar-entropy FDF. Both formulations contain the chemical reaction and its entropy generation effects in closed forms. The former constitutes the most comprehensive form of the En-FDF and provides closure for all of the unclosed terms in LES transport equations. The latter is the marginal En-FDF and accounts for entropy generation effects, as well as scalar-entropy statistics. The En-FDF methodologies are described, and some of their recent predictions of entropy statistics and entropy generation in turbulent shear flows are presented.
Mehdi Safari; Fatemeh Hadi; M. Reza H. Sheikhi. Progress in the Prediction of Entropy Generation in Turbulent Reacting Flows Using Large Eddy Simulation. Entropy 2014, 16, 5159 -5177.
AMA StyleMehdi Safari, Fatemeh Hadi, M. Reza H. Sheikhi. Progress in the Prediction of Entropy Generation in Turbulent Reacting Flows Using Large Eddy Simulation. Entropy. 2014; 16 (10):5159-5177.
Chicago/Turabian StyleMehdi Safari; Fatemeh Hadi; M. Reza H. Sheikhi. 2014. "Progress in the Prediction of Entropy Generation in Turbulent Reacting Flows Using Large Eddy Simulation." Entropy 16, no. 10: 5159-5177.
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.
M. R. H. Sheikhi; Mehdi Safari; Hameed Metghalchi. Large Eddy Simulation for Local Entropy Generation Analysis of Turbulent Flows. Journal of Energy Resources Technology 2012, 134, 041603 .
AMA StyleM. R. H. Sheikhi, Mehdi Safari, Hameed Metghalchi. Large Eddy Simulation for Local Entropy Generation Analysis of Turbulent Flows. Journal of Energy Resources Technology. 2012; 134 (4):041603.
Chicago/Turabian StyleM. R. H. Sheikhi; Mehdi Safari; Hameed Metghalchi. 2012. "Large Eddy Simulation for Local Entropy Generation Analysis of Turbulent Flows." Journal of Energy Resources Technology 134, no. 4: 041603.
A novel computational methodology, termed “Irregularly Portioned Lagrangian Monte Carlo” (IPLMC) is developed for large eddy simulation (LES) of turbulent flows. This methodology is intended for use in the filtered density function (FDF) formulation and is particularly suitable for simulation of chemically reacting flows on massively parallel platforms. The IPLMC facilitates efficient simulations, and thus allows reliable prediction of complex turbulent flames. Sample results are presented of LES of both premixed and non-premixed flames via this method, and the results are assessed via comparison with laboratory data.
S. L. Yılmaz; M. B. Nik; M. R. H. Sheikhi; P. A. Strakey; P. Givi. An Irregularly Portioned Lagrangian Monte Carlo Method for Turbulent Flow Simulation. Journal of Scientific Computing 2010, 47, 109 -125.
AMA StyleS. L. Yılmaz, M. B. Nik, M. R. H. Sheikhi, P. A. Strakey, P. Givi. An Irregularly Portioned Lagrangian Monte Carlo Method for Turbulent Flow Simulation. Journal of Scientific Computing. 2010; 47 (1):109-125.
Chicago/Turabian StyleS. L. Yılmaz; M. B. Nik; M. R. H. Sheikhi; P. A. Strakey; P. Givi. 2010. "An Irregularly Portioned Lagrangian Monte Carlo Method for Turbulent Flow Simulation." Journal of Scientific Computing 47, no. 1: 109-125.
M. R. H. Sheikhi; P. Givi; S. B. Pope. Velocity-scalar filtered mass density function for large eddy simulation of turbulent reacting flows. Physics of Fluids 2007, 19, 95106 .
AMA StyleM. R. H. Sheikhi, P. Givi, S. B. Pope. Velocity-scalar filtered mass density function for large eddy simulation of turbulent reacting flows. Physics of Fluids. 2007; 19 (9):95106.
Chicago/Turabian StyleM. R. H. Sheikhi; P. Givi; S. B. Pope. 2007. "Velocity-scalar filtered mass density function for large eddy simulation of turbulent reacting flows." Physics of Fluids 19, no. 9: 95106.
M. R. H. Sheikhi; T. G. Drozda; P. Givi; S. B. Pope. Velocity-scalar filtered density function for large eddy simulation of turbulent flows. Physics of Fluids 2003, 15, 2321 .
AMA StyleM. R. H. Sheikhi, T. G. Drozda, P. Givi, S. B. Pope. Velocity-scalar filtered density function for large eddy simulation of turbulent flows. Physics of Fluids. 2003; 15 (8):2321.
Chicago/Turabian StyleM. R. H. Sheikhi; T. G. Drozda; P. Givi; S. B. Pope. 2003. "Velocity-scalar filtered density function for large eddy simulation of turbulent flows." Physics of Fluids 15, no. 8: 2321.