The 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.

VL - 53 IS - 11-12 ER - TY - CONF T1 - Large-Scale Simulations of Supersonic Turbulent Reacting Flows T2 - 48th AIAA Aerospace Sciences Meeting Y1 - 2010 A1 - Li, Z. A1 - Jaberi, F.A. A1 - Banaeizadeh, A. AB -The 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.

JF - 48th AIAA Aerospace Sciences Meeting PB - AIAA CY - Orlando, FL ER - TY - CONF T1 - Large-Eddy Simulations of Turbulent Methane Jet Flames with Filtered Mass Density Function T2 - National Combustion Meeting Y1 - 2009 A1 - Yaldizli, M. A1 - Mehravaran, K. A1 - Jaberi, F.A. AB -The 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.

JF - National Combustion Meeting PB - The Combustion Institute CY - Ann Arbor, Michigan ER - TY - CONF T1 - Large-Scale Simulations of High Speed Turbulent Flows T2 - 47th AIAA Aerospace Sciences Meeting Y1 - 2009 A1 - Li, Z. A1 - Jaberi, F.A. AB -This 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.

JF - 47th AIAA Aerospace Sciences Meeting PB - American Institute of Aeronautics and Astronautics CY - Orlando, FL ER - TY - CONF T1 - LES/FMDF of Spray Combustion in Internal Combustion Engines T2 - National Combustion Meeting Y1 - 2009 A1 - Banaeizadeh, A. A1 - Harold Schock A1 - Jaberi, F.A. AB -The 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.

JF - National Combustion Meeting PB - The Combustion Institute CY - Ann Arbor, Michigan ER - TY - CONF T1 - Large Eddy Simulation of High Speed Turbulent Reacting Flows Y1 - 2008 A1 - Zhaorui, Li A1 - Banaeizadeh, A. A1 - Jaberi, F.A. CY - Hawaii ER - TY - CONF T1 - Large Eddy Simulations of Turbulent Flows in IC Engines T2 - ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) Y1 - 2008 A1 - Banaeizadeh, A. A1 - Afshari, A. A1 - Jaberi, F.A. A1 - H. Schock AB -A 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.

JF - ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) PB - ASME CY - Brooklyn, New York SN - 978-0-7918-4327-7 ER - TY - CONF T1 - Large Eddy Simulations of Two-Phase Turbulent Reacting Flows T2 - 46TH AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2008 A1 - Jaberi, F.A. A1 - Li, Z. JF - 46TH AIAA Aerospace Sciences Meeting and Exhibit PB - AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS CY - Reno, Nevada ER - TY - JOUR T1 - Large-Eddy Simulation of a Dispersed Particle-Laden Turbulent Round Jet JF - International Journal of Heat and Mass Transfer Y1 - 2008 A1 - Almeida, T. A1 - Jaberi, F.A. KW - Particle-laden jet; dilute KW - two-phase flows; turbulent jet; LES AB -The 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.

VL - 51 IS - 3-4 ER - TY - JOUR T1 - Large-Eddy Simulation of Turbulent Flow in an Axisymmetric Dump Combustor JF - AIAA Journal Y1 - 2008 A1 - Afshari, A. A1 - Jaberi, F.A. KW - combustion KW - Gas turbine; modeling; combustion chamber; Monte Carlo method; Lagragian Method; turbulent flow; large eddy simulation AB -A 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.

VL - 46 IS - 7 ER - TY - CONF T1 - LES/FMDF of Turbulent Combustion in Complex Flow Systems T2 - 45th AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2007 A1 - Afshari, A. A1 - Jaberi, F.A. A1 - Shih, T. I-P. AB -A 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.

JF - 45th AIAA Aerospace Sciences Meeting and Exhibit PB - AIAA CY - Reno, Nevada ER -