@article{
	11589_62257,
	author = { Coclite  A  and  Cutrone  L  and  Gurtner  M  and  De Palma  P  and  Haidn  O J  and  Pascazio  G },
	title = {Computing supersonic non-premixed turbulent combustion by an SMLD flamelet progress variable model},
	year = {2016},
	journal = {INTERNATIONAL JOURNAL OF HYDROGEN ENERGY},
	volume = {41},
	abstract = {This paper presents a statistically more likely distribution (SMLD) approach for the evaluation of the presumed probability density function (PDF) in flamelet progress variable (FPV) models for non-premixed supersonic combustion. The numerical simulation of the NASA Langley Research Center supersonic H2-Air combustion chamber is performed using two approaches: the first one is a standard FPV model, built presuming the functional shape of the PDFs of the mixture fraction, Z, and of the progress parameter, Λ; the second approach employs the SMLD technique to presume the joint PDF of Z and Λ. The standard and FPV-SMLD models have been developed using the low Mach number assumption. In both cases, the temperature is evaluated by solving the total-energy conservation equation, providing a more suitable approach for the simulation of supersonic combustion. By comparison with experimental data, the proposed SMLD model is shown to provide a clear improvement with respect to the standard FPV model, especially in the auto-ignition and stabilization regions of the flame.},
	keywords = {Hydrogen-air combustion; Joint presumed PDF modelling; Reynolds-averaged Navier-Stokes equations; Renewable Energy, Sustainability and the Environment; Fuel Technology; Condensed Matter Physics; Energy Engineering and Power Technology},
	url = {http://www.journals.elsevier.com/international-journal-of-hydrogen-energy/},
	doi = {10.1016/j.ijhydene.2015.10.086},	
	pages = {632--646}
}
@conference{
	11589_25113,
	author = { Farano M  and  Cherubini S  and  Robinet J-C  and  De Palma P },
	title = {P-norm optimal 3D perturbations in the Poiseuille flow},
	year = {2015},
	booktitle = {86th Annual Meeting
of the International Association
of Applied Mathematics and Mechanics, Book of Abstracts 2015},
	pages = {411--411}
}
@conference{
	11589_25180,
	author = { Loiseau J-C  and  Cherubini S  and  De Palma P  and  Robinet J-C },
	title = {Investigation of the roughness-induced transition: linear and
non-linear optimal perturbations},
	year = {2015},
	booktitle = {86th Annual Meeting
of the International Association
of Applied Mathematics and Mechanics, Book of Abstracts 2015},
	pages = {413--413}
}
@conference{
	11589_25121,
	author = { Farano M  and  Cherubini S  and  Robinet J-C  and  De Palma P },
	title = {A hairpin-shaped optimal perturbation in a plane Poiseuille flow},
	year = {2015},
	booktitle = {Sixth International Symposium on Bifurcation and Instabilities in fluid Dynamics},
	pages = {332--332}
}
@article{
	11589_5729,
	author = { Farano M  and  Cherubini S  and  Robinet J-C  and  De Palma P },
	title = {Hairpin-like optimal perturbations in plane Poiseuille flow},
	year = {2015},
	journal = {JOURNAL OF FLUID MECHANICS},
	volume = {775},
	abstract = {In this work it is shown that hairpin vortex structures can be the outcome of a nonlinear optimal growth process, in a similar way as streaky structures can be the result of a linear optimal growth mechanism. With this purpose, nonlinear optimizations based on a Lagrange multiplier technique coupled with a direct-adjoint iterative procedure are performed in a plane Poiseuille flow at subcritical values of the Reynolds number, aiming at quickly triggering nonlinear effects. Choosing a suitable time scale for such an optimization process, it is found that the initial optimal perturbation is composed of sweeps and ejections resulting in a hairpin vortex structure at the target time. These alternating sweeps and ejections create an inflectional instability occurring in a localized region away from the wall, generating the head of the primary and secondary hairpin structures, quickly inducing transition to turbulent flow. This result could explain why transitional and turbulent shear flows are characterized by a high density of hairpin vortices. © Cambridge University Press 2015.},
	doi = {10.1017/jfm.2015.320},	
}
@article{
	11589_1220,
	author = { Coclite A  and  Pascazio G  and  De Palma P  and  Cutrone L  and  Ihme M },
	title = {An SMLD Joint PDF Model for Turbulent Non-Premixed Combustion Using the Flamelet Progress-Variable Approach},
	year = {2015},
	journal = {FLOW TURBULENCE AND COMBUSTION},
	volume = {95},
	abstract = {This paper provides an improved flamelet/progress variable (FPV) model for the simulation of turbulent combustion, employing the statistically most likely distribution (SMLD) approach for the joint probability density function (PDF) of the mixture fraction, Ζ, and of the progress parameter, Λ. Steady-state FPV models are built presuming the functional shape of the joint PDF of Ζ and Λ in order to evaluate Favre-averages of thermodynamic quantities. The mixture fraction is widely assumed to behave as a passive scalar with a mono-modal behaviour modelled by a β-distribution. Moreover, under the hypothesis that Ζ and Λ are statistically independent, the joint PDF coincides with the product of the two marginal PDFs. In this work we discuss these two constitutive hypotheses. The proposed model evaluates the most probable joint distribution of Ζ and Λ, relaxing some crucial assumption on their statistical behaviour. This provides a more general model in the context of FPV approach and an effective tool to verify the adequateness of widely used hypotheses. The model is validated versus experimental data of well-known test cases, namely, the Sandia flames. The results are also compared with those obtained by the standard FPV approach, analysing the role of the PDF functional form on turbulent combustion simulations. © 2015 Springer Science+Business Media Dordrecht.},
	doi = {10.1007/s10494-015-9609-1},	
	pages = {97--119}
}
@conference{
	11589_25122,
	author = { Caramia G  and  Carbone G  and  De Palma P },
	title = {A two-dimensional numerical study of hydrodynamic Lubrication of Micro- Textured Surfaces},
	year = {2015},
	booktitle = {Ecotrib 2015, Book of Abstracts}
}
@conference{
	11589_25120,
	author = { Coclite A  and  Pascazio G  and  De Palma P },
	title = {A Flamelet Progress Variable model for compressible reacting flows},
	year = {2015},
	booktitle = {86th Annual Meeting
of the International Association
of Applied Mathematics and Mechanics, Book of Abstracts 2015},
	pages = {425--425}
}
@article{
	11589_894,
	author = { Caramia G  and  Carbone G  and  De Palma P },
	title = {Hydrodynamic lubrication of micro-textured surfaces: Two dimensional CFD-analysis},
	year = {2015},
	journal = {TRIBOLOGY INTERNATIONAL},
	volume = {88},
	abstract = {This paper provides a numerical study of the hydrodynamic lubrication between two parallel surfaces with micro-texturing. The two-dimensional Navier-Stokes equations for an isothermal incompressible steady flow have been considered as a suitable model. A wide variety of geometries characterised by different micro-cavity depth and width, and different gap values have been analysed in order to study the influence of these parameters on the drag force magnitude. A detailed analysis of flow velocity profiles and pressure distributions has been performed to study the forces acting on the textured surface, providing an explanation for the maximum drag reduction achievable with a single-phase lubrication fluid. Furthermore, results indicate that three regions exist, depending on the cavity depth, in which a different flow dynamics occurs and the cavities have a different influence on the drag force. Finally, an "optimal" value of the depth has been found, for which the pressure reaches a minimum value and the probability of cavitation is maximised. © 2015 Elsevier Ltd. All rights reserved.},
	doi = {10.1016/j.triboint.2015.03.019},	
	pages = {162--169}
}
@article{
	11589_5603,
	author = { Cherubini S  and  De Palma P },
	title = {Minimal-energy perturbations rapidly approaching the edge state in Couette flow},
	year = {2015},
	journal = {JOURNAL OF FLUID MECHANICS},
	volume = {764},
	abstract = {Transition to turbulence in shear flows is often subcritical, thus the dynamics of the flow strongly depends on the shape and amplitude of the perturbation of the laminar state. In the state space, initial perturbations which directly relaminarize are separated from those that go through a chaotic trajectory by a hypersurface having a very small number of unstable dimensions, known as the edge of chaos. Even for the simple case of plane Couette flow in a small domain, the edge of chaos is characterized by a fractal, folded structure. Thus, the problem of determining the threshold energy to trigger subcritical transition consists in finding the states on this complex hypersurface with minimal distance (in the energy norm) from the laminar state. In this work we have investigated the minimal-energy regions of the edge of chaos, by developing a minimization method looking for the minimal-energy perturbations capable of approaching the edge state (within a prescribed tolerance) in a finite target time T. For sufficiently small target times, the value of the minimal energy has been found to vary with T following a power law, whose best fit is given by E T-1.75. For large values of T, the minimal energy achieves a constant value which corresponds to the energy of the minimal seed, namely the perturbation of minimal energy asymptotically approaching the edge state (Rabin et al., J. Fluid Mech., vol. 738, 2012, R1). For T\geqslant 40, all of the symmetries of the edge state are broken and the minimal perturbation appears to be localized in space with a basic structure composed of scattered patches of streamwise velocity with inclined streamwise vortices on their flanks. Finally, we have found that minimal perturbations originate in a small low-energy zone of the state space and follow very fast similar trajectories towards the edge state. Such trajectories are very different from those of linear optimal disturbances, which need much higher initial amplitudes to approach the edge state. The time evolution of these minimal perturbations represents the most efficient path to subcritical transition for Couette flow. © 2015 Cambridge University Press.},
	doi = {10.1017/jfm.2014.716},	
	pages = {572--598}
}
@article{
	11589_3275,
	author = { Cherubini S  and  De Palma P  and  Robinet J-C },
	title = {Nonlinear optimals in the asymptotic suction boundary layer: Transition thresholds and symmetry breaking},
	year = {2015},
	journal = {PHYSICS OF FLUIDS},
	volume = {27},
	abstract = {The effect of a constant homogeneous wall suction on the nonlinear transient growth of localized finite amplitude perturbations in a boundary-layer flow is investigated. Using a variational technique, nonlinear optimal disturbances are computed for the asymptotic suction boundary layer (ASBL) flow, defined as those finite amplitude disturbances yielding the largest energy growth at a given target time T. It is found that homogeneous wall suction remarkably reduces the optimal energy gain in the nonlinear case. Furthermore, mirror-symmetry breaking of the shape of the optimal perturbation appears when decreasing the Reynolds number from 10?000 to 5000, whereas spanwise mirror-symmetry was a robust feature of the nonlinear optimal perturbations found in the Blasius boundary-layer flow. Direct numerical simulations show that the different evolutions of the symmetric and of the non-symmetric initial perturbations are linked to different mechanisms of transport and tilting of the vortices by the mean flow. By bisecting the initial energy of the nonlinear optimal perturbations, minimal energy thresholds for subcritical transition to turbulence have been obtained. These energy thresholds are found to be 1-4 orders of magnitude smaller than those provided in the literature for other transition scenarios. For low to moderate Reynolds numbers, the energy thresholds are found to scale with Re-2, suggesting a new scaling law for transition in the ASBL. © 2015 AIP Publishing LLC.},
	doi = {10.1063/1.4916017},	
}
@conference{
	11589_62871,
	author = { Di Renzo  M  and  Coclite  A  and  De Tullio  M D  and  De Palma  P  and  Pascazio  G },
	title = {LES of the Sandia Flame D Using an FPV Combustion Model},
	year = {2015},
	publisher = {Elsevier Ltd},
	journal = {ENERGY PROCEDIA},
	volume = {82},
	booktitle = {Energy Procedia},
	keywords = {Flamelet progress variable; Large eddy simulation; Methane-air combustion; Partialy premixed flame; Energy (all)},
	url = {http://www.sciencedirect.com/science/journal/18766102},
	doi = {10.1016/j.egypro.2015.11.824},	
	pages = {402--409}
}
@conference{
	11589_77099,
	author = { Coclite  A  and  Cutrone  L  and  De Palma  P  and  Pascazio  G },
	title = {Numerical investigation of high-pressure combustion in rocket engines using flamelet/progress-variable models},
	year = {2015},
	publisher = {American Institute of Aeronautics and Astronautics Inc, AIAA},
	booktitle = {53rd AIAA Aerospace Sciences Meeting},
	keywords = {Aerospace Engineering},
	doi = {10.2514/6.2015-1109},	
}
@conference{
	11589_77098,
	author = { Cherubini  Stefania  and  De Palma  Pietro  and  Robinet  Jean-Christophe },
	title = {Non-linear Optimal Perturbations in the Asymptotic Suction Boundary-layer},
	year = {2015},
	publisher = {Elsevier},
	journal = {PROCEDIA IUTAM},
	volume = {14},
	booktitle = {Procedia IUTAM},
	keywords = {hairpin vortices; minimal seeds; non-linear coherent structures; Transition to turbulence; Mechanical Engineering},
	url = {http://www.sciencedirect.com/science/journal/22109838/1},
	doi = {10.1016/j.piutam.2015.03.047},	
	pages = {246--255}
}
@conference{
	11589_77097,
	author = { Cherubini  S  and  Robinet  J -C  and  De Palma  P },
	title = {A nonlinear control strategy for finite-amplitude perturbations in a boundary-layer flow},
	year = {2015},
	publisher = {Elsevier Ltd},
	journal = {ENERGY PROCEDIA},
	volume = {81},
	booktitle = {Energy Procedia},
	keywords = {Blowing and suction; Optimal perturbations; Transition; Energy (all)},
	url = {http://www.sciencedirect.com/science/journal/18766102},
	doi = {10.1016/j.egypro.2015.12.139},	
	pages = {1143--1150}
}
@article{
	11589_519,
	author = { Cherubini S  and  De Palma P },
	title = {Minimal perturbations approaching the edge of chaos in a Couette flow},
	year = {2014},
	journal = {FLUID DYNAMICS RESEARCH},
	volume = {46},
	abstract = {This paper provides an investigation of the structure of the stable manifold of the lower branch steady state for the plane Couette flow. Minimal energy perturbations to the laminar state are computed, which approach within a prescribed tolerance the lower branch steady state in a finite time. For small times, such minimal-energy perturbations maintain at least one of the symmetries characterizing the lower branch state. For a sufficiently large time horizon, such symmetries are broken and the minimal-energy perturbations on the stable manifold are formed by localized asymmetrical vortical structures. These minimal-energy perturbations could be employed to develop a control procedure aiming at stabilizing the low-dissipation lower branch state. © 2014 The Japan Society of Fluid Mechanics and IOP Publishing Ltd.},
	doi = {10.1088/0169-5983/46/4/041403},	
}
@article{
	11589_1310,
	author = { Bruno D  and  Panarese A  and  Diomede P  and  Longo S  and  Taccogna F  and  Minelli P  and  Surzhikov S T  and  Dikaljuk A S  and  De Palma P  and  de Tullio M D },
	title = {Particle Methods for Nonequilibrium Hypersonic and Plasma Flows},
	year = {2014},
	journal = {THE OPEN PLASMA PHYSICS JOURNAL},
	volume = {7},
	pages = {88--100}
}
@article{
	11589_3591,
	author = { Cherubini S  and  Robinet J-C  and  De Palma P },
	title = {Numerical study of the effect of freestream turbulence on by-pass transition in a boundary layer},
	year = {2014},
	journal = {ENERGY PROCEDIA},
	volume = {45},
	abstract = {We use direct numerical simulations in the presence of free-stream turbulence having different values of intensity, Tu, and integral length scale, L, in order to determine which kind of structures are involved in the path to transition of a boundary-layer flow. The main aim is to determine under which conditions the path to transition involves structures similar to the linear or non-linear optimal perturbations. For high values of Tu and L, we observe a large-amplitude path to transition characterized by localized vortical structures and patches of high- and low-momentum fluctuations. Such a scenario is found to correlate well with the Λ and hairpin structures resulting from the time evolution of non-linear optimal perturbations, whereas, for lower Tu and L, a larger correlation is found with respect to linear optimal disturbances. This indicates that a large-amplitude path to transition exists, different from the one characterized by elongated streaks undergoing secondary instability. To distinguish between the two transition scenarios, a simple parameter linked to the streamwise localisation of high- and low-momentum zones is introduced. Finally, an accurate law to predict the transition location is provided, taking into account both Tu and L, valid for both the transition scenarios.},
	keywords = {Boundary-layer flows; Optimal perturbations; Transition to turbulence},
	doi = {10.1016/j.egypro.2014.01.062},	
	pages = {578--587}
}
@conference{
	11589_23353,
	author = { Pappalettere C  and  De Palma P  and  Pascazio G  and  De Tullio M  and  Camporeale S  and  Dambrosio L  and  Fortunato B  and  Torresi M  and  Fornarelli F  and  Carbone G  and  Afferrante L  and  Bottiglione F  and  Mantriota G  and  Foglia MM  and  Demelio G  and  Ciavarella M  and  Lamberti L  and  Boccaccio A  and  Ludovico AD  and  Csmpanelli SL  and  De Filippis LAC  and  Tricarico L  and  Palumbo G  and  Sorgente D  and  Scintilla LD  and  Galantucci LM  and  Percoco G  and  Lavecchia F  and  Casavola C  and  Naso N  and  Lino P  and  Maione G  and  Stasi S  and  Turchiano B  and  Cupertino F },
	title = {Advanced technologies for reduction of polluting emissions, fuel consumption and
operating costs of Heavy Duty engines, INNOVHEAD},
	year = {2014},
	volume = {Track A},
	booktitle = {Atti del "1st WORKSHOP on the State of the art and Challenges Of Research Efforts @ POLIBA"}
}
@conference{
	11589_22830,
	author = { Trovato M A  and  Cupertino F  and  De Tuglie E E  and  Dicorato M  and  Naso D  and  Stasi S  and  Turchiano B  and  Cafaro G  and  Cagnano A  and  Forte G  and  Mastromauro R A  and  Camporeale S  and  De Palma P  and  Fortunato B  and  Pascazio G  and  Torresi M  and  Caramia G  and  Ranaldo S  and  Petrillo A F  and  Mossa M  and  Malcangio D  and  Ben Meftah M  and  Bruno M F  and  De Serio F  and  Fanelli G  and  Gratton V  and  Intranuovo G  and  Lattaruli M  and  Molfetta M G  and  Papagni P  and  Pratola L  and  Romanazzi G L  and  Saponieri A },
	title = {Project PONa3_00372 “Innovative Processes for Energy
Conversion – PrInCE”},
	year = {2014},
	publisher = {Gangemi Editore spa},
	address = {Roma},
	volume = {Track A},
	booktitle = {ONGOING RESEARCH PROJECTS - GRANDI PROGETTI IN ATTO},
	abstract = {In the framework of European funds for Convergence regions managed by the Italian Ministry for Research Education, Politecnico di Bari has applied a
project for structural development of laboratories named “Innovative Processes for Energy Conversion – PrInCE”. This paper is meant to describe the research and
development activities involving the Laboratories developed within the PrInCE
project.},
	keywords = {Laboratory improvement, Distributed Generation Supervision and Control, Field tests and demonstrators.},
	pages = {515--525}
}