Vincent Giovangigli

Bio: Vincent Giovangigli is an academic researcher from École Polytechnique. The author has contributed to research in topics: Diffusion flame & Partial differential equation. The author has an hindex of 32, co-authored 122 publications receiving 3598 citations. Previous affiliations of Vincent Giovangigli include École Centrale Paris & University of Paris.

Multicomponent Flow Modeling

Abstract: We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves, also termed anchored waves. We further discuss related models which have a similar hyperbolic-parabolic structure, notably the Saint-Venant system with a temperature equation as well as the equations governing chemical equilibrium flows. We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure. We finally discuss numerical algorithms specifically devoted to complex chemistry flows, in particular the evaluation of multicomponent transport properties, as well as the impact of multicomponent transport.

Multicomponent transport algorithms

Abstract: The authors present a general and self-contained theory of iterative algorithms for evaluating transport coefficients in multicomponent, and especially dilute polyatomic gas mixtures thus filling a gap left by other books that give preference to pure (mostly monatomic) gases and to binary mixtures Approximate expressions for the transport coefficients are rigorously derived from the kinetic theory These can be readily used, at a reduced computational cost, in numerical models Hence, the present algorithms will be of extensive interest in theoretical calculations and numerical modeling for fluid mechanics, combustion, crystal growth, and other engineering applications The material is covered rigorously and comprehensively, and every mathematical step is marefully explained

Extinction of Strained Premixed Laminar Flames With Complex Chemistry

Abstract: Conclusions derived from the solution of premixed laminar flames in a stagnation point flow are important in the determination of chemically controlled extinction limits and in the ability to characterize the combustion processes occurring in turbulent reacting flows. In the neighborhood of the stagnation point produced in these flames, a chemically reacting boundary layer is established. For a given equivalence ratio, the input flow velocity can be varied and solutions can be determined for increasing values of the strain rate. As the strain rate increases, the flame nears extinction. Recent experimental, computational and theoretical work has shown that extinction of these flames can be achieved by either flame stretch or by a combination of flame stretch and incomplete chemical reaction. Extinction by flame stretch is possible when the Lewis number of the deficient reactant is greater than a critical value and extinction resulting from both flame stretch and incomplete chemical reaction is pos...

Thermal diffusion effects in hydrogen-air and methane-air flames

Abstract: The influence of thermal diffusion on the structure of hydrogen-air and methane-air flames is investigated numerically using complex chemistry and detailed transport models. All the transport coefficients in the mixture, including thermal diffusion coefficients, are evaluated using new algorithms which provide, at moderate computational costs, accurate approximations derived rigorously from the kinetic theory of gases. Our numerical results show that thermal diffusion is important for an accurate prediction of flame structure. §E-mail address: ern@cermics.enpc.fr ∥E-mail address: giovangi@cmapx.polytechnique.fr

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Jacobian-free Newton-Krylov methods: a survey of approaches and applications

Abstract: Jacobian-free Newton-Krylov (JFNK) methods are synergistic combinations of Newton-type methods for superlinearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations to the Jacobian matrix may still be required for preconditioning the resulting Krylov iteration. As with Krylov methods for linear problems, successful application of the JFNK method to any given problem is dependent on adequate preconditioning. JFNK has potential for application throughout problems governed by nonlinear partial differential equations and integro-differential equations. In this survey paper, we place JFNK in context with other nonlinear solution algorithms for both boundary value problems (BVPs) and initial value problems (IVPs). We provide an overview of the mechanics of JFNK and attempt to illustrate the wide variety of preconditioning options available. It is emphasized that JFNK can be wrapped (as an accelerator) around another nonlinear fixed point method (interpreted as a preconditioning process, potentially with significant code reuse). The aim of this paper is not to trace fully the evolution of JFNK, nor to provide proofs of accuracy or optimal convergence for all of the constituent methods, but rather to present the reader with a perspective on how JFNK may be applicable to applications of interest and to provide sources of further practical information.

Traveling wave solutions of parabolic systems

Abstract: Part I. Stationary waves: Scalar equation Leray-Schauder degree Existence of waves Structure of the spectrum Stability and approach to a wave Part II. Bifurcation of waves: Bifurcation of nonstationary modes of wave propagation Mathematical proofs Part III. Waves in chemical kinetics and combustion: Waves in chemical kinetics Combustion waves with complex kinetics Estimates and asymptotics of the speed of combustion waves Asymptotic and approximate analytical methods in combustion problems (supplement) Bibliography.