Christophe Dumouchel

Christophe Dumouchel
CORIA · TASC

PhD

About

88
Publications
8,026
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1,363
Citations
Citations since 2017
15 Research Items
557 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100

Publications

Publications (88)
Article
Multiphase flows reveal contorted fluid structures which cannot be described in terms of drop/bubble diameter distribution. Here we use a morphological descriptor which originates from the field of heterogeneous materials that was proved to be nicely tailored for characterizing the microstructure of e.g. porous media. It is based on the Minkowski F...
Article
Full-text available
Liquid transport in scale space - Volume 886 - F. Thiesset, B. Duret, T. Ménard, C. Dumouchel, J. Reveillon, F. X. Demoulin
Article
Full-text available
This paper reports an experimental method for extracting the extensional properties of viscoelastic liquids during atomization. As a first approach, low-velocity free jets are considered. Such jets of viscoelastic liquids break with the formation of a beads-on-a-string pattern composed of quasi-spherical beads and quasi-cylindrical ligaments. The l...
Article
Full-text available
The experimental work reported in this paper addresses the question of the description of a textural atomization process including the atomizing structures and the resulting drops. Textural atomization process designates a deformation leading to drop-production localized on the liquid–gas interface of a liquid flow: droplets appear like peeled from...
Article
Ligamentary structures are often encountered in liquid atomization processes. They appear for instance during the atomization of liquid sheets issuing from triple-disk nozzles. Because of the development of turbulence along the internal wall of the discharge orifice, these sheets are highly perturbed and exhibit the formation of ligaments along the...
Conference Paper
Full-text available
In a recent work, a protocol to measure the relaxation time of dilute polymer solutions, known to be challenging,has been established [1]. This protocol is based on a 2D multi-scale description of free-falling low velocity viscoelastic liquid jets. Although the relaxation time reached an asymptotic value for high jet velocities, a significant depen...
Conference Paper
Full-text available
This study employs DNS of two-phase flows to enhance primary atomization understanding and modelling to beused in numerical simulation in RANS or LES framework. In particular, the work has been aimed at improving the information on the liquid-gas interface evolution available inside the Eulerian-Lagrangian Spray Atomization (ELSA) framework. Even t...
Conference Paper
A multi-scale approach to investigate liquid atomization processes is introduced. It describes the liquid system by the scale distribution whose determination is inspired from the Euclidean Distance Mapping used to measure the fractal dimension of a contour. The scale distribution is introduced in 2D and in 3D and applications from previous investi...
Article
A multi-scale analyzing tool is now available to investigate the temporal evolution of two phase flows such as liquid systems experiencing an atomization process. Thanks to its multi-scale and global nature, it allows identifying all dynamics simultaneously involved in the process with no restriction of the liquid system shape. In the present work...
Article
This paper presents the 3-D multi-scale analysis of a cylindrical liquid ligament subjected to a capillary instability. This analysis aims to investigate the evolution of the ligament interface paying a specific attention to the physical mechanisms involved at small scales. The capillary instability behavior is obtained from direct numerical simula...
Article
A multiresolution tomographic algorithm to reconstruct drop-size distribution and liquid volume concentration within local regions of sprays is proposed. The reconstruction procedures allow the size of the local regions to be designed adaptively such that the reconstruction results can be obtained at multiple resolutions. The algorithm uses the str...
Conference Paper
Full-text available
A multi-scale analysis of the capillary instability of Newtonian liquid ligament is presented. The DNS code ARCHER calculates the temporal evolution of the ligament subject to a capillary instability for two initial wavenumbers. The analysis of the process is performed with a multi-scale approach initially developed to investigate liquid atomisatio...
Conference Paper
Full-text available
A multi-scale tool has been recently introduced to describe liquid atomization processes captured by visuali-zations. This tool performs a measurement of the specific length of the system as a function of the scale of observation. It has been applied on several experimental results and, each time, appeared pertinent. The present contribution contin...
Article
The atomization of individual liquid ligaments appearing during the disintegration of liquid sheets issuing from a triple-disk injector is investigated. High-speed visualizations report a temporal evolution of the ligaments from their production to their disintegration into drops. The parameter of the experiments is the surface tension of the liqui...
Article
Full-text available
Recent investigations have presented an application of the scale entropy diffusion theory to model liquid atomization process. This theory describes multi-scale behavior by a diffusion equation of the scale entropy function. In atomization, this function is related to the scale-distribution which provides a measurement of the specific-length of the...
Presentation
Full-text available
This 2015 presentation gives an overal look at the multiscale analysis tool set, as well as describes our early attempts at multiscale analysis of the atomizing jet using a static, thin control window. Part of the resuts presented here will most likely never be published, as they have been superseded by ones obtained with newer solver versions. Thi...
Conference Paper
Full-text available
Printed antenna based on 2D-images of a fractal liquid jet has been designed and analyzed numerically. In this work, the effect of the structure’s size on the antenna behavior was presented. The return loss, radiation patterns and surface current densities were simulated over the frequency band 1-20 GHz for 3 different sizes of the structure. It is...
Conference Paper
Full-text available
Printed antenna based on 2D-images of a fractal liquid jet has been designed and analyzed numerically. In this work, the effect of the structure's size on the antenna behavior was presented. The return loss, radiation patterns and surface current densities were simulated over the frequency band 1-20 GHz for 3 different sizes of the structure. It is...
Conference Paper
Full-text available
A planar printed dipole antenna with reflectors and directors, able to steer its radiation pattern in different directions, is proposed for telecommunication applications. Starting from a dual-beam printed dipole antenna achieved by combining two elementary dipoles back to back, and by loading four PIN diodes, three modes of reconfigurable radiatio...
Article
The objective of the present experimental and analytical investigation is to acquire a better understanding and appreciation of the volume-based drop-diameter distribution measured by laserdiffraction technique (LDT) when probing sprays with a significant rate of nonspherical drops. Experiments are performed on sprays of several liquids with a LDT...
Conference Paper
Full-text available
This paper reports the development of an adaptive tomographic reconstruction algorithm to measure local properties of a solid-cone spray generated from a pressure swirl atomizer. The technique has been applied to measure local drop-size distributions and local extinction coefficients of the spray simultaneously and at multi-resolutions. Input data...
Article
This experimental work investigates the influence of the geometry of GDI devices on primary atomization processes under low injection pressure and reduced back pressure. These pressure conditions ensure cavitating flows and observable atomization processes. Measurements include mass flux, structure velocity from high-speed visualizations and spray...
Conference Paper
Full-text available
This paper proposes an adaptive deconvolution algorithm to reconstruct local drop-size distributions within liquid sprays at multiple resolutions by using the laser diffraction measurement data. The algorithm employs the strip integration by which the scattered light intensities from the local regions along the measured line-of-sight being integrat...
Article
Full-text available
This paper focuses on recent developments in numerical simulations and experimental techniques applied to jet atomization. Interface tracking based on coupled level-set, VOF, and ghost fluid approaches is presented, together with experimental methods including morphological analysis, multi-scale analysis, and laser correlation velocimetry. Experime...
Article
The determination of a universal mathematical function to represent liquid spray drop-size distribution is still debated in the literature. The ability of such a mathematical function is usually quantified by exploring its capability to represent experimental data. Since experimental diagnostics are not sensible to the same spray characteristics, w...
Article
Liquid atomization processes are mechanisms during which the shape of the liquid system continuously varies. This can be evidenced and quantified by measuring the surface-based scale distribution that continuously evolves from the nozzle exit down to the spray region. The description of this evolution is associated to a time- and scale-dependent fr...
Article
A method to determine time-dependent volume-based drop-diameter distribution of an evaporating group of drops heterogeneous in size and distributed over an entire cross-section of a water spray is proposed in this paper. Using the fact that the number of drops does not change during evaporation while their size decreases following the D2-law, the t...
Article
The Laser-Diffraction Technique (LDT) based on the analysis of the light diffraction pattern forwardly scattered by droplets going through a laser optical probe, reports a drop-diameter distribution. As reported by previous investigations this drop-diameter distribution is sensitive to the shape of the drops and LDT measures an equivalent-diameter...
Article
Full-text available
This paper applies the D 2 -law to a group of heterogeneous size of biodiesel drops in order to determine the time evolution of the drop-size distribution and its burn-out time. Experiments to determine initial drop distribution data, used for predicting the evaporation time, have been performed on a biodiesel spray issuing from a small scale indus...
Article
Full-text available
The Maximum Entropy Formalism (MEF) has been used to model dimensionless mass-based drop-diameter distribution data at local position within a spray generated from a small industrial burner. The function is in turn used to predict evaporation time of the group of drops employing the dimensionless D 2 -law. Three different fluids: water, diesel and...
Article
Acoustic instabilities with frequencies roughly higher than 1 kHz remain among the most harmful instabilities, able to drastically affect the operation of engines and even leading to the destruction of the combustion chamber. By coupling with resonant transverse modes of the chamber, these pressure fluctuations can lead to a large increase of heat...
Article
The traditional use of the laser diffraction technique provides line-of-sight liquid spray drop-size distribution. However, deconvolution of the measurements can be performed for axisymmetric spray in order to determine local spray characteristics. In a previous publication, a new deconvolution technique making use of the maximum entropy principle...
Article
Full-text available
The efficiency of any application involving a liquid spray is known to be highly dependent on the spray characteristics, and mainly, on the drop-diameter distribution. There is therefore a crucial need of models allowing the prediction of this distribution. However, atomization processes are partially known and so far a universal model is not avail...
Article
Whatever the situation, liquid atomization processes show a continuous evolution of the liquid system shape. However, such a system is a multiscale object, i.e., its shape cannot be fully described by a single geometrical parameter. The present work makes use of the scale entropy function to describe this multiscale object. This function is found s...
Article
This paper reports an experimental investigation on the practical use of a laser-diffraction instrument, the Malvern Spraytec 2007 to characterize sprays produced by a high-pressure GDI injector. The sprays are highly transient, large, composed of very small drops, dense and heterogeneously distributed in space. These characteristics are at the ori...
Article
This paper presents a theoretical and an experimental investigation of low-velocity cylindrical liquid jets submitted to transverse planar acoustic waves. For this purpose, the behavior of a liquid jet traversing the section of a Kundt tube was examined. Experiments reported that the liquid jet could be either deviated from its trajectory or deform...
Article
The production of a liquid spray can be summarized as the succession of the following three steps; the liquid flow ejection, the primary breakup mechanism and the secondary breakup mechanism. The intermediate step—the primary breakup mechanism—covers the early liquid flow deformation down to the production of the first isolated liquid fragments. Th...
Article
This work deals with a particular breakup mode experienced by cylindrical liquid jets when submitted to an intense transverse acoustic wave. Experiments on low speed water jets (< 1 ms) of diameters 3 mm and 6 mm show that sound waves with a frequency ranging from 500 Hz to 1800 Hz can produce bulges along the jet. When the sound level is high enou...
Article
The three-parameter, Generalized Gamma function solution of a recent MEF formulation used to derive liquid spray drop-size distribution, is applied to sprays resulting from three different atomization processes. The objectives of these applications are to determine the sign of the parameters for which this function reports a more reliable fit and t...
Article
The drop-size distribution is a very important characteristic of liquid sprays. From a mathematical point of view these distributions are defined for spherical drops. Furthermore, the experimental diagnostics widely used to measure spray drop-size distribution characterize the droplets by a single length-scale equivalent to a diameter. However, mor...
Article
The work reported in this paper questions the relevance of using fractal concept to study liquid primary atomization process by characterizing the shape of the continuous liquid flow from the nozzle exit to the end of the atomization process. First, three fractal methods were tested on synthetic images in order to define the best adapted protocol t...
Article
This work proposes a new deconvolution technique to obtain local drop size distributions from line-of-sight intensity data measured by laser diffraction technique. The tomographic reconstruction, based on the maximum entropy (ME) technique, is applied to forward scattered light signal from a laser beam scanning horizontally through the spray on eac...
Article
Considering the differences and disagreements involving the previous application of the Maximum Entropy Formalism to modeling the drop-size distribution of liquid sprays, a new formulation is suggested. The constraints introduced in this formulation are based on characteristic features common to any liquid atomization process, i. e., the production...
Article
This work presents the experimental validation of a new deconvolution technique that calculates local drop size distributions from line-of-sight laser diffraction measurements. Previous deconvolution techniques are based on the onion peeling method but errors cumulate at each inward step of the calculation and the calculation always reports unreali...
Article
The present work questions the problem of the mathematical form to be given to physical information used as constraints required by the MEF to predict spray drop size distribution. The MEF formulation used was developed in the first part of this study. It makes use of statistical mechanics and the specified information limits the production of both...
Article
For more than twenty years, Maximum Entropy Formalism has been used to predict spray drop size distribution. The analysis of the solutions reported by these approaches shows that their difference is due to an appropriate definition of the information introduced in the formalism. This observation allows suggesting a new formulation where the specifi...
Article
This work, presented n wo parts, investgates he relevance of using fractal analysis o characterize and study quid flow atomzaton processes. In he first part, it was shown hat the EDM methods o determne he fractal dimension was he best adapted o measure eiher textural or structural local fractal dimension. The part of this study, which is reported n...
Article
This work, presented n wo parts, nvestgates he relevance of using fractal analysis o characterize and study lquid flow atomzaton processes and participates o he required effort of conductng experimental nvestgatons on primary break-up processes. This first part ackles he problem of he method. Several methods o determne fractal dimension are availab...
Article
The present paper reports an experimental investigation on atomizing liquid flows produced by simplified cavity nozzles. The Weber number being kept low, the sprays produced by these injectors depend on the liquid flow characteristics only, and more precisely, on the non-axial kinetic energy and of the turbulent kinetic energy at the nozzle exit. T...
Article
At low Weber numbers, the aerodynamic forces due to the interaction between gas and liquid do not influence liquid atomization processes. In these situations, atomization processes depend on issuing liquid flow characteristics only. According to the literature, the atomization efficiency is best when the issuing liquid flow shows a high turbulence...
Article
Full-text available
The present paper reports an experimental investigation on the performance of the Spraytec, the recent particle sizer commercialized by Malvern Instruments, Malvern, UK. As with the previous Malvern particle sizers, the Spraytec provides a volume-based drop-size distribution from the analysis of a diffraction pattern resulting from the interaction...
Article
A recent application of the Maximum Entropy Formalism on liquid atomization problems led to the development of a mathematical volume-based drop-size distribution. This function, which depends on three parameters, is a reduction of the four-parameter generalized Gamma function. The aim of the present work is to investigate the relevance of the three...
Article
Full-text available
In many atomization processes, the injection pressure is too small to rely on the action of the aerodynamic forces to help in the production of small drops. In such a situation, an alternative consists in producing issuing liquid flow with complex internal structures. According to studies found in the literature, energetic internal flow structures...
Article
The present article reports an experimental investigation on the characterization of the atomization of plain cylindrical liquid jets. The main objective of the work is to measure the stability nerve of jets produced by two different injectors, one of them being dedicated to low-pressure fire-port-injected engines. Furthermore, in order to investig...
Article
The origin of the critical point of a cylindrical liquid jet, first maximum of the stability curve, is not fully understood so far. In a previous experimental investigation, three different jet regimes of atomization were defined according to the influence of the gas density on the jet critical velocity. Whether a jet is in a given regime was found...
Article
This paper reports an investigation on the volume-based drop size distribution of sprays produced by swirl atomizers dedicated to direct-injection spark-ignited engines. Because of the use of high injection pressures to reduce the atomization time, the spatial density of the spray is high and prevents from classical measurements of spray drop size...
Article
This paper presents an investigation on the experimental determination of some characteristics of the flow issuing from a swirl injector dedicated to direct-injection spark-ignited engines. The reproducibility, from one injection to another, of the temporal evolution of the liquid flow characteristics during the opening of the injector was investig...
Article
This work is an extension of a previous investigation on the determination of mathematical volume-spray drop size distributions by the application of the maximum entropy formalism. A two-parameter drop size distribution was derived and was found to give reasonable fits with experimental distributions obtained under different experimental conditions...
Article
This paper reports a study of the linear stability of an annular liquid sheet evolving in a gaseous environment at rest. In this investigation, the viscosity of the liquid is taken into account. As has been found in similar approaches developed for other liquid systems, the results reveal the presence of a dominant wave and a cut-off wave number fo...
Article
The work reported in this paper is an extension of a previous study on the prediction of volume-based drop size distribution from the application of the maximum entropy formalism (M.E.F.). The procedure developed in that study led to the derivation of a two-parameter distribution. The present work investigated the problem of the determination of th...
Article
The atomisation of liquids by means of low-frequency ultrasonic atomisers results from unstable surface waves generated on the free surface of a thin liquid film. These unstable waves are obtained from the tuning of the amplitude and the frequency of an imposed oscillation. The thin liquid film develops as the liquid spreads over the atomising surf...
Article
An excited cylindrical water jet is studied by using a laser beam technique for jet shape characterizations. A laser sheet is scattered by a jet allowing to record highly-sampled time series to track the evolution of the jet diameter. With such a technique, the perturbation growth of an excited water jet is investigated from the needle to break-up....
Article
This paper reports the results of an experimental investigation on the disintegration of cylindrical liquid jets. The aim of this work is to shed more light on the physics responsible for the break-up of low speed liquid jets through an analysis of the stability curve and mainly of the development of its first maximum i.e. the critical point. The e...
Article
The procedure to predict drop size distributions, described in the first part of this paper, is tested on two different types of injector, namely, pressure swirl atomizer and low pressure pintle-type injectors. In each case, the linear theory is applied and the resulting theoretical drop diameter is introduced as information in the Maximum Entropy...
Article
The study presented in this paper reconsiders the use of the Maximum Entropy Formalism (M.E.F.) for the prediction of spray drop size distribution. This formalism is a statistical tool that allows the prediction of a probability distribution consistently with information related to the process studied. The study first shows that the formalism has t...
Article
The atomization of liquids by means of low frequency ultrasonic atomizers results from unstable surface waves generated on the free surface of a thin liquid film. These unstable waves are obtained from the tuning of the amplitude and the frequency of an imposed oscillation. The thin liquid film develops as the liquid spreads over the atomizing surf...
Article
There are very few theoretical approaches dealing with the prediction of drop size distribution in spray, and it is still impossible to evaluate this important spray characteristic from theoretical considerations only. However, for the past 10 years the use of the maximum entropy formalism for this task has opened new directions of investigation. U...
Article
This article reports an experimental investigation on the disintegration of cylindrical jets through a study of the stability curve. We are interested mainly in the behavior of lowvelocity jets in order to understand the development of the critical point, the first maximum on the stability curve. The experimental results obtained for a jet of water...
Article
The mathematical investigation presented in this article with the behavior of free viscous liquid sheets. The aim of this work is to show the competition among the aerodynamic, surface tension, and viscous forces in the disintegration process, audio deduce the situations in which the liquid viscosity introduces nonnegligible effects. The approach i...
Book
Contains 136 refereed papers in 1100 pages
Article
In this paper a numerical analysis is carried out of the velocity field throughout a swirl spray nozzle and more specially at the orifice. After an examination of the parameters involved in the problem, it is found that the characteristics of the conical liquid sheet produced at the nozzle's orifice are mainly functions of the geometry of the nozzl...
Article
Physical processes involved in pulverizing systems are classified generally as 1) pressure atomizers in which a liquid sheet is injected in a calm atmosphere or 2) air-blast atomizers: in this last case, liquid velocity is relatively low and pulverization is achieved through a high velocity air flow. In both cases destabilizing forces are due to an...

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Projects (2)
Project
Development of optical techniques for the measurement of drop size, drop shape and drop size distribution. Modelling image formation and determine objective image analysis for liquid-gas interface identification.