A multicomponent droplet evaporation model which discretizes the one-dimensional mass and temperature profiles inside a droplet with a finite volume method has been developed and implemented into a large-eddy simulation ({LES)} model for spray simulations. The {LES} and multicomponent models were used along with the {KH-RT} secondary droplet breakup model to simulate realistic fuel sprays in a closed vessel. The effect of various spray and ambient gas parameters on the liquid penetration length of different single component and multicomponent fuels was investigated. The numerical results indicate that the spray penetration length decreases non-linearly with increasing gas temperature or pressure and is less sensitive to changes in ambient gas conditions at higher temperatures or pressures. The spray models and {LES} were found to predict the experimental results for n-hexadecane and two multicomponent surrogate diesel fuels reasonably well.

%I {SAE} International %C Warrendale, {PA} %G eng %U http://papers.sae.org/2013-01-1603/ %9 {SAE} Technical Paper %0 Journal Article %J Phys. Rev. Lett. %D 2012 %T Nanomechanical energy storage in twisted nanotube ropes %A Teich, David %A Fthenakis, Zacharias G. %A Seifert, Gotthard %A David Tománek %B Phys. Rev. Lett. %I American Physical Society %V 109 %P 255501 %8 Dec %G eng %0 Journal Article %J J. Chem. Phys. %D 2011 %T Nanoconfinement effects on the reversibility of hydrogen storage in ammonia borane: A first-principles study %A Chang, Kiseok %A Kim, Eunja %A Weck, Philippe F. %A David Tománek %B J. Chem. Phys. %V 134 %P 214501 %G eng %0 Journal Article %J \apj %D 2011 %T The Nature of the Warm/Hot Intergalactic Medium. I. Numerical Methods, Convergence, and O VI Absorption %A Smith, B. D. %A Hallman, E. J. %A Shull, J. M. %A O'Shea, B. W. %K cosmology: observations %K intergalactic medium %K quasars: absorption lines %B \apj %V 731 %P 6-+ %G eng %0 Journal Article %J Int. J. of Heat and Mass Transfer %D 2010 %T Non-Equilibrium Molecular Dynamics Study of Thermal Energy Transport in Au-SAM-Au Junctions %A Tengfei Luo %A John R. Lloyd %B Int. J. of Heat and Mass Transfer %V 53 %G eng %0 Conference Paper %B 48th AIAA Aerospace Sciences Meeting %D 2010 %T Numerical Investigations of Shock-Turbulence Interactions in a Planar Mixing Layer %A Li, Z. %A Jaberi, F.A. %XDirect numerical simulation (DNS) and large-eddy simulation (LES) of spatially developing supersonic mixing layer, interacting with an oblique shock wave are conducted with a new high-order Monotonicity-Preserving scheme. Without the incident shock, the mixing layer grows linearly and exhibits self-similar behavior after the transition. With the shock, significant small-scale turbulence is generated just behind the shock. With an increase in shock angle, the intensity of the shock-generated turbulence is increased and its peak position shifts away from the mixing layer centerline. The effects of turbulence on the shock are also shown to be very significant, such that normal shocklets and large adverse pressure gradients are created in some conditions. Comparison with the DNS data indicates that the LES with the modified kinetic energy viscosity (MKEV) subgrid stress model is able to predict the main features of the flow and shock-turbulence interactions.

%B 48th AIAA Aerospace Sciences Meeting %I AIAA %C Orlando, FL %8 01/2010 %G eng %0 Conference Paper %B National Combustion Meeting %D 2009 %T A New Model for Numerical Simulations of Two-Phase Turbulent Combustion %A Li, Z. %A Jaberi, F.A. %B National Combustion Meeting %I National Combustion Meeting %C Ann Arbor, MI %8 05/2009 %G eng %0 Conference Paper %B SAE World Congress and Exhibit %D 2009 %T Numerical Simulation of a Direct-Injection Spark-Ignition Engine with Different Fuels %A S. Srivastava %A Harold Schock %A Jaberi, F.A. %A David Hung %XThis paper focuses on the numerical investigation of the mixing and combustion of ethanol and gasoline in a single-cylinder 3-valve direct-injection spark-ignition engine. The numerical simulations are conducted with the KIVA code with global reaction models. However, an ignition delay model mitigates some of the deficiencies of the global one-step reaction model and is implemented via a two-dimensional look-up table, which was created using available detailed kinetics models. Simulations demonstrate the problems faced by ethanol operated engines and indicate that some of the strategies used for emission control and downsizing of gasoline engines can be employed for enhancing the combustion efficiency of ethanol operated engines.

%B SAE World Congress and Exhibit %I SAE International %C Detroit, Michigan %8 04/2009 %G eng %0 Journal Article %J PLoS Computational Biology %D 2008 %T Natural selection fails to optimize mutation rates for long-term adaptation on rugged fitness landscapes %A Clune, J. %A Misevic, D. %A Ofria, C. %A Lenski, R.E. %A Elena, S.F. %A Sanjuán, R. %B PLoS Computational Biology %I Public Library of Science %V 4 %P e1000187 %G eng %0 Book Section %B Electron Correlation Methodology %D 2007 %T New Alternatives for Accurate Electronic Structure Calculations of Potential Energy Surfaces Involving Bond Breaking %A Piotr Piecuch %A I. S. O. Pimienta %A P.-D. Fan %A K. Kowalski %XThe method of moments of coupled-cluster equations (MMCC) is extended to potential energy surfaces involving multiple bond breaking by developing the quasi-variational (QV) and quadratic (Q) variants of the MMCC theory. The QVMMCC and QMMCC methods are related to the extended CC (ECC) theory, in which products involving cluster operators and their deexcitation counterparts mimic the effects of higher-order clusters. The test calculations for N2 show that the QMMCC and ECC methods can provide spectacular improvements in the description of multiple bond breaking by the standard CC approaches.

%B Electron Correlation Methodology %S ACS Symposium Series %I American Chemical Sociegy %C Washington, DC %V 958 %@ ISBN13: 9780841238435 %G eng %0 Conference Paper %B Proceedings of the 43rd AIAA/ASME/SAI/ASEE Joint Propulsion Conference %D 2007 %T A New Model for Large Eddy Simulations of Multi-Phase Turbulent Combustion %A Yaldizli, M. %A Li, Z. %A J.A. Jaberi %XNumerical simulations of a spray-controlled lean premixed dump combustor are con- ducted via a two-phase large eddy simulation (LES) methodology. In this methodology, the velocity field is obtained by a high-order finite difference method. The subgrid gas- liquid combustion closure is based on the two-phase filtered mass density function (FMDF) method and the spray is modeled with a Lagrangian scheme. The effects of spray, fuel/air composition, and inflow/outflow conditions on the combustion are investigated. It has been found that the main features of the turbulence and combustion inside the dump combustor are very differently modified by the spray for different spray parameters. The LES/FMDF results also indicate the significance of the inflow and outflow conditions.

%B Proceedings of the 43rd AIAA/ASME/SAI/ASEE Joint Propulsion Conference %I AIAA/ASME/SAI/ASEE %C Cincinnati, Ohio %8 07/2007 %G eng %0 Conference Proceedings %B ASME Conference Proceedings, Computers and Information in Engineering Conference %D 2007 %T Numerical Simulations of Two-Phase Turbulent Combustion in Spray Burners %A Li, Z. %A Yaldizli, M. %A Jaberi, F.A. %XThe complex interactions among turbulence, combustion and spray in liquid-fuel burners are modeled and simulated via a new two-phase Lagrangian-Eulerian-Lagrangian large eddy simulation (LES) methodology. In this methodology, the spray is modeled with a Lagrangian mathematical/computational method which allows two-way mass, momentum and energy coupling between phases. The subgrid gas-liquid combustion is based on the two-phase filtered mass density function (FMDF) that has several advantages over “conventional” two-phase combustion models. The LES/FMDF is employed in conjunction with non-equilibrium reaction and droplet models. Simulations of turbulent combustion in a spray-controlled double-swirl burner are conducted via LES/FMDF. The generated results are used for better understanding of spray combustion in realistic turbulent flow configurations. The effects of spray angle, mass loading ratio, fuel type, droplet size distribution, wall and inflow/outflow conditions on the flow and combustion are investigated. The LES/FMDF predictions are shown to be consistent with the experimental results.

%B ASME Conference Proceedings, Computers and Information in Engineering Conference %I ASME %C Las Vegas, Nevada %8 09/2007 %@ 0-7918-4803-5 %G eng %0 Journal Article %J Journal of Molecular Structure: THEOCHEM %D 2006 %T Non-Iterative Coupled- Cluster Methods Employing Multi-Reference Perturbation Theory Wave Functions %A Piotr Piecuch %A M.D. Lodriguito %A K. Kowalski %A M. Wloch %K Coupled-cluster theory; Equation-of-motion coupled-cluster methods; Method of moments of coupled-cluster equations; Multi-reference perturbation theory; Non-iterative coupled-cluster methods %XA new class of non-iterative coupled-cluster (CC) methods, which improve the results of standard CC and equation-of-motion (EOM) CC calculations for ground and excited-state potential energy surfaces along bond breaking coordinates and for excited states dominated by two-electron transitions, is explored. The proposed approaches combine the method of moments of coupled-cluster equations (MMCC), in which the a posteriori corrections due to higher-order correlations are added to standard CC/EOMCC energies, with the multi-reference many-body perturbation theory (MRMBPT), which provides information about the most essential non-dynamic and dynamic correlation effects that are relevant to electronic quasi-degeneracies. The performance of the basic MRMBPT-corrected MMCC approximation, in which inexpensive non-iterative corrections due to triple excitations are added to ground- and excited-state energies obtained with the CC/EOMCC singles and doubles approach, is illustrated by the results of a few test calculations, including bond breaking in HF and H2O, and excited states of CH+.

%B Journal of Molecular Structure: THEOCHEM %V 771 %P 89-104 %8 10/2006 %G eng %N 1-3 %0 Book Section %B Progress in Theoretical Chemistry and Physics %D 2006 %T Non-iterative Coupled-Cluster Methods for Excited Electronic States %A Piotr Piecuch %A M. Wloch %A M. Lodriguito %A J. R Gour %B Progress in Theoretical Chemistry and Physics %V 15 %P 45-106 %G eng %0 Journal Article %J Molecular Physics %D 2005 %T Noniterative Corrections to Extended Coupled-Cluster Energies Employing the Generalized Method of Moments of Coupled-Cluster Equations %A Piotr Piecuch %A {P.-D.} Fan %A K. Kowalski %XIt is shown that the extended coupled-cluster method with singles and doubles (ECCSD) does not suffer from the non-variational collapse observed in the standard CCSD calculations when multiple bond breaking is examined. This interesting feature of the single-reference ECCSD theory is used to design the non-iterative CC methods with singles, doubles and non-iterative triples and quadruples, which provide a highly accurate and variational description of potential energy surfaces involving multiple bond breaking with computational steps that scale as with the system size. This is accomplished with the help of the generalized version of the method of moments of coupled-cluster equations (GMMCC), which can be used to correct the results of non-standard CC calculations, such as ECCSD. The theoretical considerations are illustrated by the preliminary results of the ECCSD-based GMMCC calculations for triple bond breaking in N2. Keywords: Coupled-cluster theory; Extended coupled-cluster method; Method of moments of coupled-cluster equations; Non-iterative coupled-cluster approaches; Bond breaking

%B Molecular Physics %V 103 %P 2191-2213 %8 08/2005 %G eng %N 15 & 16 %0 Journal Article %J Nuclear Physics A %D 2005 %T Nuclear Structure Calculations with Coupled-Cluster Methods from Quantum Chemistry %A Piotr Piecuch %A D. J. Dean %A J. R Gour %A G. Hagen %A M. {Hjorth-Jensen} %A K. Kowalski %A T. Papenbrock %A M. Wloch %XWe present several coupled-cluster calculations of ground and excited states of 4He and 16O employing methods from quantum chemistry. A comparison of coupled cluster results with the results of exact diagonalization of the hamiltonian in the same model space and other truncated shell-model calculations shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei, with much less computational effort than traditional large-scale shell-model approaches. Unless truncations are made, for nuclei like 16O, full-fledged shell-model calculations with four or more major shells are not possible. However, these and even larger systems can be studied with the coupled cluster methods due to the polynomial rather than factorial scaling inherent in standard shell-model studies. This makes the coupled cluster approaches, developed in quantum chemistry, viable methods for describing weakly bound systems of interest for future nuclear facilities.

%B Nuclear Physics A %V 752 %P 299-308 %8 04/2005 %G eng