Large Eddy Simulations of atomization and evaporation of liquid fuel sprays in diesel engine conditions are performed with stochastic breakup and non-equilibrium droplet heat and mass transfer models. The size and number density of the droplets generated by the breakup model are assumed to be governed by a Fokker-Planck equation, describing the evolution of the {PDF} of droplet radii. The fragmentation intensity spectrum is considered to be Gaussian and the scale of Lagrangian relative velocity fluctuations is included in the breakup frequency calculations. The aerodynamic interactions of droplets in the dense part of the spray are modeled by correcting the relative velocity of droplets in the wake of other droplets. The stochastic breakup model is employed together with the wake interaction model for simulations of non-evaporating and evaporating sprays in various gas temperature and pressure conditions. The predicted results for physical spray parameters, such as the spray penetration length are found to be in good agreement with the available experimental data.

%I {SAE} International %C Warrendale, {PA} %G eng %U http://papers.sae.org/2013-01-1101/ %9 {SAE} Technical Paper %0 Conference Proceedings %B 43rd AIAA Fluid Dynamics Conference %D 2013 %T Large Eddy Simulation of Spray Mixing and Combustion with Two-Phase Filtered Mass Density Function %A Irannejad, A %A Jaberi, F. %B 43rd AIAA Fluid Dynamics Conference %C San Diego, California %G eng %0 Journal Article %D 2013 %T Large-Eddy Simulations of Turbulent Flows in Internal Combustion Engines, International Journal of Heat and Mass Transfer %A Banaeizadeh, A. %A Afshari, A. %A H. Schock %A Jaberi, F. %V Vol. 60 %G eng %N No. 10 %& 781-796 %0 Conference Paper %B 26th Large Installation System Administration conference {LISA) %D 2012 %T Lessons Learned When Building a Greenfield High Performance Computing Ecosystem %A Keen, Andrew %B 26th Large Installation System Administration conference {LISA) %C San Diego, California, USA %G eng %0 Journal Article %J Soil Sci. Soc Am J %D 2011 %T Long-term differences in tillage and land use affect intra-aggregate pore heterogeneity %A A.N. Kravchenko %A W. Wang %A A.J.M. Smucker %A M.L. Rivers %B Soil Sci. Soc Am J %V 75 %P 1658-1666 %G eng %0 Journal Article %J PLoS One %D 2010 %T A landscape and climate data logistic model of tsetse distributions in Kenya %A Moore, Nathan %A Messina, Joseph %B PLoS One %V 5 %8 07/2010 %G eng %N 7 %0 Conference Paper %B 48th AIAA Aerospace Sciences Meeting %D 2010 %T Large -Scale Simulations of Incident Shock-Turbulent Boundary Layer Interactions %A A. Jammalamadaka %A Jaberi, F.A. %B 48th AIAA Aerospace Sciences Meeting %C Orlando, FL %8 01/2010 %G eng %0 Journal Article %J International Journal of Heat and Mass Transfer %D 2010 %T Large-Eddy Simulations of Turbulent Methane Jet Flames with Filtered Mass Density Function %A Yaldizli, M. %A Mehravaran, K. %A Jaberi, F.A. %K Filtered mass density function; PDF methods; Monte-Carlo simulations; Methane jet flames %K LES %XThe filtered mass density function (FMDF) model (Jaberi et al. 1999 [1]) is employed for large eddy simulations (LES) of “high speed” partially-premixed methane jet flames with the “flamelet” and “finite-rate” kinetics models. The FMDF is the joint probability density function (PDF) of the scalars and is determined via the solution of a set of stochastic differential equations. The LES/FMDF is implemented using a highly scalable, parallel hybrid Eulerian–Lagrangian numerical scheme. The LES/FMDF results are shown to compare well with the experimental data for all flow conditions when “appropriate” reaction and mixing models are employed.

%B International Journal of Heat and Mass Transfer %V 53 %P 2551-2562 %8 05/2010 %G eng %N 11-12 %0 Conference Paper %B 48th AIAA Aerospace Sciences Meeting %D 2010 %T Large-Scale Simulations of Supersonic Turbulent Reacting Flows %A Li, Z. %A Jaberi, F.A. %A Banaeizadeh, A. %XThe scalar filtered mass density function (FMDF) is further developed and employed for large-eddy simulations (LES) of high speed turbulent flows in complex geometries. LES/FMDF is implemented via an efficient, hybrid numerical method. In this method, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved with a generalized, high-order, multi-block, compact differencing scheme. Turbulent mixing and combustion are modeled with the FMDF. The LES/FMDF method is used for simulations of isotropic turbulent flow in a piston-cylinder assembly, the flow in a shock tube and a supersonic co-axial helium-air jet. The critical role of pressure in the FMDF equation when applied to compressible flows is studied. It is shown that LES/FMDF is reliable and is able to simulate compressible turbulent mixing and combustion in supersonic flows.

%B 48th AIAA Aerospace Sciences Meeting %I AIAA %C Orlando, FL %8 01/2010 %G eng %0 Conference Paper %B American Institute of Physics Conference Series %D 2010 %T Local and Global Radiative Feedback from Population III Star Formation %A O'Shea, B. W. %A Whalen, D. J. %E {D. J. Whalen, V. Bromm, %E N. Yoshida} %K Distances %K Population III stars %K Pre-main sequence objects %K protostellar clouds %K radial velocities %K radiative transfer %K redshift %K redshifts %K scattering %K spatial distribution of galaxies %K star formation %K young stellar objects and protostars %B American Institute of Physics Conference Series %S American Institute of Physics Conference Series %V 1294 %P 128-133 %G eng %0 Conference Paper %B National Combustion Meeting %D 2009 %T Large-Eddy Simulations of Turbulent Methane Jet Flames with Filtered Mass Density Function %A Yaldizli, M. %A Mehravaran, K. %A Jaberi, F.A. %XThe filtered mass density function (FMDF) model (Jaberi et al. 1999 [1]) is employed for large eddy simulations (LES) of “high speed” partially-premixed methane jet flames with the “flamelet” and “finite-rate” kinetics models. The FMDF is the joint probability density function (PDF) of the scalars and is determined via the solution of a set of stochastic differential equations. The LES/FMDF is implemented using a highly scalable, parallel hybrid Eulerian–Lagrangian numerical scheme. The LES/FMDF results are shown to compare well with the experimental data for all flow conditions when “appropriate” reaction and mixing models are employed.

%B National Combustion Meeting %I The Combustion Institute %C Ann Arbor, Michigan %8 05/2009 %G eng %0 Conference Paper %B 47th AIAA Aerospace Sciences Meeting %D 2009 %T Large-Scale Simulations of High Speed Turbulent Flows %A Li, Z. %A Jaberi, F.A. %XThis paper briefly describes a new class of high-order Monotonicity-Preserving (MP) finite difference methods recently developed for direct numerical simulation (DNS) and large-eddy simulation (LES) of high-speed turbulent flows. The MP method has been implemented together with high-order compact (COMP) and weighted essentially non- oscillatory (WENO) methods in a generalized three-dimensional (3D) code and has been applied to various 1D, 2D and 3D problems. For the LES, compressible versions of the gradient-based subgrid-scale closures are employed. Detailed and extensive analysis of various flows indicates that MP schemes have less numerical dissipation and faster grid convergence than WENO schemes. Simulations conducted with high-order MP schemes preserve sharp changes in flow variables without spurious oscillations and capture the turbulence at the smallest simulated scales. The non-conservative form of the scalar equation solved with MP schemes are shown to generate the same results as COMP schemes for supersonic mixing problems involving shock waves.

%B 47th AIAA Aerospace Sciences Meeting %I American Institute of Aeronautics and Astronautics %C Orlando, FL %8 01/2009 %G eng %0 Journal Article %J International Journal of Quantum Chemistry %D 2009 %T Left-Eigenstate Completely Renormalized Equation-of-motion Coupled-Cluster Methods: Review of Key Concepts, Extension to Excited States of Open-Shell Systems, and Comparison with Electron-Attached and ionized Approaches %A Piotr Piecuch %A J. R Gour %A M. Wloch %XThe recently proposed left-eigenstate completely renormalized (CR) coupled-cluster (CC) method with singles, doubles, and noniterative triples, termed CR-CC(2,3) Piecuch and Włoch, J Chem Phys, 2005, 123, 224105; Piecuch et al. Chem Phys Lett, 2006, 418, 467 and the companion CR-EOMCC(2,3) methodology, which has been previously applied to singlet excited states of closed-shell molecular systems Włoch et al. Mol Phys, 2006, 104, 2149 and in which relatively inexpensive noniterative corrections due to triple excitations derived from the biorthogonal method of moments of CC equations (MMCC) are added to the CC singles and doubles (CCSD) or equation-of-motion (EOM) CCSD energies, have been extended to excited states of open-shell species. The resulting highly efficient computer codes for the open-shell CR-EOMCC(2,3) approach exploiting the recursively generated intermediates and fast matrix multiplication routines have been developed and interfaced with the GAMESS package, enabling CR-EOMCC(2,3) calculations for singlet as well as nonsinglet ground and excited states of closed- and open-shell systems using the restricted Hartree–Fock or restricted open-shell Hartree–Fock references. A number of important mathematical and algorithmic details related to formal aspects and computer implementation of the CR-EOMCC(2,3) method have been discussed, in addition to overviewing the key concepts behind the CR-EOMCC(2,3) and biorthogonal MMCC methodologies for ground and excited states, and the numerical results involving low-lying states of the CH, CNC, C2N, N3, and NCO species, including states dominated by two-electron transitions, have been presented. The results of the CR-EOMCC(2,3) calculations have been compared with other CC/EOMCC approaches, including the EOMCCSD and EOMCC singles, doubles, and triples methods, and their full and active-space valence counterparts based on the electron-attached and ionized EOMCC methodologies, and the predecessor of CR-EOMCC(2,3) termed CR-EOMCCSD(T) Kowalski and Piecuch, J Chem Phys, 2004, 120, 1715. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

%B International Journal of Quantum Chemistry %V 109 %P 3268-3304 %8 11/2009 %G eng %N 14 %0 Conference Paper %B National Combustion Meeting %D 2009 %T LES/FMDF of Spray Combustion in Internal Combustion Engines %A Banaeizadeh, A. %A Harold Schock %A Jaberi, F.A. %XThe two-phase filtered mass density function (FMDF) model is employed for large-eddy simulation (LES) of turbulent spray combustion in internal combustion (IC) engines. The LES/FMDF is implemented with an efficient, hybrid numerical method. In this method, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved with a generalized, high-order, multi-block, compact differencing scheme. The spray and the FMDF are implemented with Lagrangian methods. The LES/FMDF methodology has been used for simulations of turbulent combustion in a rapid compression machine (RCM) and in a direct-injection spark-ignition (DISI) engine. For both RCM and DISI engine, the complex interactions among turbulent velocity, fuel droplets and combustion are shown to be well captured with the LES/FMDF. The results for the DISI engine indicate that the size, velocity, evaporation and combustion of the sprayed fuel droplets are strongly affected by the unsteady, vortical motions generated by the incoming air during the intake stroke. In turn, the droplets are found to change the in-cylinder flow structure.

%B National Combustion Meeting %I The Combustion Institute %C Ann Arbor, Michigan %8 05/2006 %G eng %0 Journal Article %J The Journal of Chemical Physics %D 2009 %T Local Correlation Calculations Using Standard and Renormalized Coupled-Cluster Approaches %A Wei Li %A Piotr Piecuch %A J. R Gour %A Shuhua Li %Xhe linear scaling local correlation approach, termed “cluster-in-molecule” (CIM), is extended to the coupled-cluster (CC) theory with singles and doubles (CCSD) and CC methods with singles, doubles, and noniterative triples, including CCSD(T) and the completely renormalized CR-CC(2,3) approach. The resulting CIM-CCSD, CIM-CCSD(T), and CIM-CR-CC(2,3) methods are characterized by (i) the linear scaling of the CPU time with the system size, (ii) the use of orthonormal orbitals in the CC subsystem calculations, (iii) the natural parallelism, (iv) the high computational efficiency, enabling calculations for much larger systems and at higher levels of CC theory than previously possible, and (v) the purely noniterative character of local triples corrections. By comparing the results of the canonical and CIM-CC calculations for normal alkanes and water clusters, it is shown that the CIM-CCSD, CIM-CCSD(T), and CIM-CR-CC(2,3) approaches accurately reproduce the corresponding canonical CC correlation and relative energies, while offering savings in the computer effort by orders of magnitude.

%B The Journal of Chemical Physics %V 131 %8 09/2009 %G eng %N 11 %0 Journal Article %J Molecular Physics %D 2009 %T Low-Lying Valence Excited States of CNC, C₂N, N₃ and NCO Studied Using the Electron-Attached and Ionized Symmetry-Adapted Cluster Configuration-Interaction and Equation-of-Motion Coupled-Cluster Methodologies %A M. Ehara %A J. R Gour %A Piotr Piecuch %XLow-lying valence excited states of four open-shell triatomic molecules, CNC, C2N, N3, and NCO, are investigated using the electron-attached (EA) and ionized (IP) symmetry-adapted-cluster configuration-interaction (SAC-CI) general-R as well as the full and active-space EA and IP equation-of-motion coupled-cluster (EOMCC) methods. A comparison is made with experiment and with the results of the completely renormalized (CR) CC calculations with singles, doubles, and non-iterative triples defining the CR-CC(2,3) approach. Adiabatic excitation energies of the calculated states are in reasonable agreement with the experimental values, provided that the 3-particle-2-hole (3p-2h) components in the electron attaching operator, as in the EA SAC-CI SDT-R and EA EOMCCSD(3p-2h) approaches, are included in the calculations for the excited states of C2N and CNC which have a predominantly two-electron character. The results also reveal that the active-space EA/IP EOMCC schemes with up to 3p-2h/3h-2p excitations are able to accurately reproduce the results of their much more expensive parent methods while requiring significantly less computational effort. Furthermore, the more 'black-box' CR-CC(2,3) approach calculates the lowest state of each symmetry with the same accuracy as that obtained with the EA/IP SAC-CI SDT-R and EA/IP EOMCCSD(3p-2h/3h-2p) methods, confirming the significance of higher-order correlation effects in obtaining an accurate description of excited states of radicals, particularly the valence excited states of the CNC and C2N species dominated by two-electron processes.

%B Molecular Physics %V 107 %P 871-880 %8 04/2009 %G eng %N 8-12 %0 Conference Paper %D 2008 %T Large Eddy Simulation of High Speed Turbulent Reacting Flows %A Zhaorui, Li %A Banaeizadeh, A. %A Jaberi, F.A. %C Hawaii %8 12/2008 %G eng %0 Conference Paper %B ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) %D 2008 %T Large Eddy Simulations of Turbulent Flows in IC Engines %A Banaeizadeh, A. %A Afshari, A. %A Jaberi, F.A. %A H. Schock %XA new computational methodology is developed and tested for large eddy simulation (LES) of turbulent flows in internal combustion (IC) engines. In this methodology, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved via a generalized, high-order, multi-block, compact differencing scheme and various subgrid-scale (SGS) stress closures. Both reacting and nonreacting flows with and without spray are considered. The LES models have been applied to a piston-cylinder assembly with a stationary open valve and harmonically moving flat piston. The flow in a direct-injection spark-ignition (DISI) engine is also considered. It is observed that during the intake stroke of the engine operation, large-scale unsteady turbulent flow motions are developed behind the intake valves. The physical features of these turbulent motions and the ability of LES to capture them are studied and tested by simulating the flow in a simple configuration involving a stationary valve. The flow statistics predicted by LES are shown to compare well with the available experimental data. The DISI configuration includes all the complexities involved in a realistic single-cylinder IC engine, such as the complex geometry, moving valves, moving piston, spray and combustion. The spray combustion is simulated with the recently developed two-phase filtered mass density (FMDF) model.

%B ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) %I ASME %C Brooklyn, New York %8 08/2008 %@ 978-0-7918-4327-7 %G eng %0 Conference Paper %B 46TH AIAA Aerospace Sciences Meeting and Exhibit %D 2008 %T Large Eddy Simulations of Two-Phase Turbulent Reacting Flows %A Jaberi, F.A. %A Li, Z. %B 46TH AIAA Aerospace Sciences Meeting and Exhibit %I AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS %C Reno, Nevada %8 01/2008 %G eng %L AIAA 2008-1154 %0 Journal Article %J International Journal of Heat and Mass Transfer %D 2008 %T Large-Eddy Simulation of a Dispersed Particle-Laden Turbulent Round Jet %A Almeida, T. %A Jaberi, F.A. %K Particle-laden jet; dilute %K two-phase flows; turbulent jet; LES %XThe numerical results obtained by large-eddy simulation (LES) of a particle-laden axisymmetric turbulent jet are compared with the available experimental data. The results indicate that with a new stochastic subgrid-scale (SGS) closure, the effects of the particles on the carrier gas and those of the carrier gas on the particles are correctly captured by the LES. Additional numerical experiments are conducted and used to investigate the effects of particle size, mass-loading ratio, and other flow/particle parameters on the statistics of both the carrier gas phase and the particle dispersed phase.

%B International Journal of Heat and Mass Transfer %V 51 %P 683-695 %8 2/2008 %G eng %N 3-4 %0 Journal Article %J AIAA Journal %D 2008 %T Large-Eddy Simulation of Turbulent Flow in an Axisymmetric Dump Combustor %A Afshari, A. %A Jaberi, F.A. %K combustion %K Gas turbine; modeling; combustion chamber; Monte Carlo method; Lagragian Method; turbulent flow; large eddy simulation %XA hybrid Eulerian–Lagrangian, mathematical/computational methodology is developed and evaluated for large- eddy simulations of turbulent combustion in complex geometries. The formulation for turbulence is based on the standard subgrid-scale stress models. The formulation for subgrid-scale combustion is based on the filtered mass density function and its equivalent stochastic Lagrangian equations. An algorithm based on high-order compact differencing on generalized multiblock grids is developed for numerical solution of the coupled Eulerian–Lagrangian equations. The results obtained by large-eddy simulations/filtered mass density function show the computational method to be more efficient than existing methods for similar hybrid systems. The consistency, convergence, and accuracy of the filtered mass density function and its Lagrangian–Monte Carlo solver is established for both reacting and nonreacting flows in a dump combustor. The results show that the finite difference and the Monte Carlo numerical methods employed are both accurate and consistent. The results for a reacting premixed dump combustor also agree well with available experimental data. Additionally, the results obtained for other nonreacting turbulent flows are found to be in good agreement with the experimental and high-order numerical data. Filtered mass density function simulations are performed to examine the effects of boundary conditions, subgrid-scale models, as well as physical and geometrical parameters on dump-combustor flows. The results generated for combustors with and without an inlet nozzle are found to be similar as long as appropriate boundary conditions are employed.

%B AIAA Journal %V 46 %P 1576-1592 %8 07/2008 %G eng %N 7 %0 Conference Paper %B 45th AIAA Aerospace Sciences Meeting and Exhibit %D 2007 %T LES/FMDF of Turbulent Combustion in Complex Flow Systems %A Afshari, A. %A Jaberi, F.A. %A Shih, T. I-P. %XA high-order Lagrangian/Eulerian method based on the the filtered mass density func- tion (FMDF) for subgrid-scale (SGS) combustion closure was developed to perform large eddy simulation (LES) of turbulent reacting flows in complex geometrical configurations in multi-block structured grids. In particular, an efficient algorithm has been developed to search and locate particles in multi-block, hexahedral-structured grid system. Also, the consistency, convergence, and accuracy of the FMDF and the Monte Carlo solution of its equivalent stochastic differential equations were assessed. The consistency between Eulerian and Lagrangian fields were established for a reacting flow in a dump combustor. The results obtained for a reacting flow in an axisymmetric, premixed dump-combustor, were found to compare favorably with measured experimental data.

%B 45th AIAA Aerospace Sciences Meeting and Exhibit %I AIAA %C Reno, Nevada %8 01/2007 %G eng