A postdoctoral position is available in the particulate flow group of IUSTI CNRS Polytech'Marseille, a research institute based in Marseille in the South of France, see

http://iusti.polytech.univ-mrs.fr/~gep/index.html

The proposed post-doctoral project aims at understanding the erosion and transport by shearing flows of solid heavy particles forming an erodible bed. The objective of the study is to provide a better knowledge of the coupling between the granular bed and the fluid flow, and a more complete description of the bed structures, in particular the dune patterns, which are observed in closed channels or pipes. The theoretical investigation will use a continuum approach, i.e. a two-phase modelling, which will be implemented into a 3D numerical code.

Candidates should be motivated by analytical and numerical modelling. The position is funded for 2 years and the salary is approximately 25 000 euros per year. The candidates should have a Ph.D. degree or equivalent and can be nationals of any country.

Elisabeth Guazzelli

A Post-doc fellowship is available financed by the European Community within the Marie Curie Research and Training Network 'Mountain Risks: from prediction to management and governance' to carry out research on the mechanical analysis of landslide fluidization processes. The work of the Post-Doc fellow is to get better insight into the mechanical and hydrological conditions susceptible to trigger mudflows through acceleration and/or fluidization of landslides. The main study area will be the Trièves in the French Alps. This 300 km2 area is covered by a thick Quaternary clay layer (up to 200 m) deposited in a glacially dammed lake during the Würm period. After the glacier melting, rivers have cut deeply into the superficial geological formations, triggering numerous landslides.

Requirements: Recently obtained Ph.D in Geomechanics, Civil Engineering, Geophysics, or related disciplines. A Ph.D in the same area of research is highly desirable. Eligibility: As requested by the EC, applicants can not seek the position in his/her country of origin or residence, or in the country where the applicant holds her/his Ph.D. Starting date: July 1st 2008.

Conditions of employment: The appointment will be given in reference to the Cemagref's rules. The fellowship duration is 12 months + 12 months at a rate of 2150 ⬠gross per month. The applicant will benefit from supplementary allowances that will enable him/her to spend a substantial amount of his/her time at the secondment institutes. These allowances are a mobility allowance which amount depends on the family charges of the applicant, a Career Exploratory Allowance and one visit per year to the home country.

Please note that the official application deadline is 2008, April 30, so interested applicants should establish contact as soon as possible..

Dr. Guillaume Chambon.

Knowledge and control of the mechanical properties (rheology, plasticity, ...) of media confined in molecular thicknesses is of paramount importance in fields ranging from (i) friction and boundary lubrication to (ii) the design of polymer nanocomposites. In this perspective, the postdoctoral researcher will take part in an experimental project which aims at :
(i) gaining better understanding of the flow properties of model lubricants which, when "mechanically quenched" , i.e. rapidly confined down to nm-thick films, display a behavior in marked contrast with both that of the bulk state and that of the equilibrium confined liquid [Phys. Rev. Lett. 99, 225503 (2007)].
(ii) probing the impact of  chemical interactions with the confining walls on the frictional properties of polymer ultrathin films [Phys. Rev. Lett. 97, 225501 (2006)]. These experiments will be performed using a surface force apparatus recently developed in our group. <\p>

The candidate should hold a PhD in experimental physics with a background in soft condensed matter. She/he will quickly reach full autonomy in performing non-standard experiments on a custom-made setup. Skills in micro/nano mechanical or rheological probing of soft solids will be highly appreciated. Experience in physico-chemical control/modification of surfaces will be a plus.<\p>

Lionel Bureau.

The Subsurface Flow and Transport Team in the Hydrology, Geology and Geochemistry (EES-6) group of the Earth and Environmental Sciences Division at Los Alamos National Laboratory is seeking outstanding applicants for postdoctoral positions. The successful applicants will be have education, training, and experience in model development for subsurface flow and transport processes on various scales. Potential research topics include multiphase flow and transport, reactive solute transport, flow and transport in fractures, particle-tracking simulation on unstructured grids, and decision analysis under uncertainty. This work will contribute to ongoing interdisciplinary investigations that include LANL Environmewntal Investigations, the Yucca Mountain Projects, oil shale projects, and Nevada Test Site Environmental Projects.

The Earth and Environmental Sciences Division employs about 300 people, including many postdoctoral associates, with expertise in many facets of earth science. The Subsurface Flow and Transport Team is interdisciplinary, working on a wide randge of problems related to analysis and simulation of multi-phase / multi-component flow and reactive transport in saturated and unsaturated media. We provide access to advanced numerical simulation codes and state-of-the-art computing facilities within our division and at LANL.

Required skills: Applicants must have a strong background in hydrogeology and demonstrated experience in conceptualization and numerical development of subsurface flow and transport models. Applicants should be proficient in one or more programming or scripting language.

Desired skills: Preference will be given to applicants experienced with multi-processor computational environments and integrating state-of-the-art theoretical developments in the area of flow and transport modeling with analysis of field data. A demonstrated record of peer-reviewed publications is also highly desirable.

Education: A Ph.D. in Hydrology, Geosciences, or Engineering completed within the last five years or soon to be completed is required.

Velimir Vesselinov.

Fluidization of water-saturated granular media happens in various contexts : underwater avalanches, turbidites, landslides after important rainfall, soil fluidization triggered by seismic waves. These events are important geophysical alea, with associated risks causing human and material damage. During this fluidization, the pressure rise of the interstitial fluid plays a major role. Different mechanisms can be activated. Indeed, in a granular medium, fluids can accumulate over lowly permeable and mechanically weak barriers, and induce then important deformations by an instable mobilization of the solid matrix. In the case of a seismic initiation, the transit of a seismic wave can induce a resonance between the interstitial fluid flow and the wave propagation, which can fluidize the material. We will study this fluidization transitions and avalanche triggering processes in a laboratory analog model: a transparent tank mounted on a tilted table. The origin of the avalanche and fluidization sources considered will be a/ internal interstitial pressure sources, and b/ seismic wave propagations. The resulting avalanche nucleation will be imaged using a fast optical camera (1000 frames/sec), and pressure and flux measuring devices. The deformation field can be determined using image subtraction techniques [Lovoll, Toussaint et al 2004, Toussaint, Lovoll et al 2005], and correlation image velocimetry (CIV) techniques [Chambon, Schmittbuhl and Corfdir 2003]. The seismic waves will be generated using a 64 channel ultrasonic acoustic station.

The candidate will have a strong taste for physics and mechanics of natural media. Notions in one or several of the following domains will be appreciated: Mechanics of granular media, flow in porous media, numerical analysis of experimental data, laboratory experiments, seismic wave propagation and / or poroelasticity, multiparticle simulations (molecular dynamics or contact dynamics). The prerequisites are a good knowledge of scientific english language, a basic knowledge of the linux system, and the knowledge of a programming language (a priori, C, C++, Fortran77 or Fortran90).

Salary : between 2000 and 3000 euros net, according to experience, including social security. Duration: 1 year (starting in 2007 or 2008)

Renaud.Toussaint@eost.u-strasbg.fr.

A two-year EPSRC-funded postdoctoral research position is available in the School of Chemical and Environmental Engineering at the University of Nottingham, to investigate  'Jamming and stress-induced heterogeneity in colloidal suspensions and granular materials.' The project will involve experiments on the flow of concentrated particulates, colloids and granulars, with a view to understanding the interdependent roles of jamming, dilation and stress-induced spatial heterogeneity in different flow situations. Despite a historical effort spanning at least 300 years (with notable contributions from, for instance, Coulomb, Reynolds and Bagnold), basic understanding of the stress response of particulates and granulars remains elusive, as does the ability to relate fundamental concepts to real applications. Applying stress and flow in situ in observation rigs comprising microscopes and other custom-made apparatus, the project will investigate fundamental aspects of the behaviour of 'model' experimental materials, relating them to real applications such as food, mineral and other product processing. The research will be based in newly-refurbished laboratory facilities, making use of brand new optical, microscopy, and digital video equipment. The School is excellently provided with IT, computer and library facilities. Substantial opportunities for collaboration exist within the School and with major groups in the Schools of Physics, Chemistry, Food Sciences, and other Engineering Schools. The project start date is negotiable but should be as soon as possible after the beginning of July 2007. Annual salary will be on the Research & Teaching level 4 pay scale, in the range £24,402-£30,913. Candidates should have a PhD, or substantial industrial experience, in a relevant field such as the physics or engineering of granulars or soft matter. Demonstrable ability to carry out independent, careful, creative, organised experimental work will be an advantage, as will be a willingness to span the divide between fundamental sciences and engineering applications. Applications, including a covering letter summarising your research interests and experience and a curriculum vitae, should be addressed directly to Dr Mark Haw, School of Chemical, Environmental and Mining Engineering, University of Nottingham, Nottingham NG7 2RD. .

For further details and informal discussions contact Dr Mark Haw, tel. +44 (0)115 9514178, email mark.haw@nottingham.ac.uk.

A postdoctoral research appointment is available in the Mechanical Engineering Department at the University of New Mexico to perform research in multiphase suspension flows. The successful candidate should have an excellent background in fluid and computational mechanics with experience in either molecular dynamics or boundary element methods. The appointment will be made for one year with the possibility of renewal for a second year.

Candidates for this position should submit a letter of application, resume, and names of three references to:  Professor Marc Ingber, University of New Mexico, Department of Mechanical Engineering, Albuquerque, NM 87131. E-mail applications will also be accepted at ingber@me.unm.edu.

Tema: Estudio teórico y experimental de la dinámica de las corrientes de gravedad, tanto de aquellas que aparecen en el fondo como en la superficie o en niveles intermedios de una capa de fluido, generadas en canales de sección transversal no rectangular, a través de la liberación repentina de un volumen de agua salada en agua (o viceversa) sobre substratos impermeables o porosos y en diferentes geometrías

Descrpción: Se propone estudiar los flujos generados por la acción de la gravedad en diversas situaciones físicas a través de experiencias de laboratorio para proveer una explicación de su conducta global y predecir sus consecuencias. Se adaptarán distintas diagnósticas (Shadowgraph, Schlieren sintáctico, LIF, PTV) y softwares específicos de procesamiento digital de imágenes para obtener la información física relevante de los experimentos y se establecerán relaciones entre las corrientes analizadas en el laboratorio y fenómenos naturales de interés geofísico (como flujos de intercambio en estuarios y canalizaciones angostas) y ambiental (como los flujos generados en el interior de edificios naturalmente ventilados o la liberación accidental a la atmósfera de gases mas densos que el aire) considerando los criterios de similaridad fluido dinámica adecuados.

Tema: Estudio de la circulación y el transporte de sedimentos y elementos disueltos en las aguas del estuario del río Quequén generados por las mareas, la descarga del río y el flujo del agua usada por la central termoeléctrica, y sus interrelaciones con la geomorfología, la hidrografía, el viento, los procesos biológicos presentes y los diferentes factores sociales involucrados, a fin de obtener la información objetiva necesaria para promover el desarrollo sustentable de la zona de influencia.

Descrpción: Combinando experimentos de laboratorio, datos de campo y modelado analítico, se espera profundizar en la dinámica de la circulación en el estuario del río Quequén Grande, influenciada por el continuo dragado, la actividad portuaria, los flujos superficiales de agua cálida procedentes de la usina termoeléctrica, los derrames de hidrocarburos, flujos de efluentes cloacales o industriales, etc. El becario participará de las campañas, utilizará los diversos instrumentos de medición y a procesar e interpretar la información adquirida.

Urgent. The study fits in one of the priority of the team “Instabilities, Turbulence and Control”, namely the comprehension of the interactions between actuators and a boundary layer, separated or not. Indeed, all works on flow control imply the choice of actuators which will interact with a target flow. Very often, work passes by an important parametric study because of the lack of knowledge of the phenomena brought into play when the actuators interact with the flow. We thus decided to develop an original activity based on the analysis of the interaction between actuators and boundary layers. Among the various types of possible actuators, we are interested in the Vortex Generators (VG) which, in general, are Generators of Longitudinal Vortices (with the vorticity aligned with the flow). In this family one can distinguish the Mechanical Vortex Generators (vane, solid obstacles of various forms placed in the boundary layer) form Fluidic Vortex Generators. We already carried out many studies on the mechanical Vortex Generators and we now wish to extend our exploration to the Fluidic Vortex Generators, and also to Pulsated Jets.

The use of pulsated jets for flow control is considered as one of the most promising ways for control of the separated flows, and this for several reasons. The first is due to the favourable energy balance: the energy required is smaller for a pulsated jet. The second is due to the existence of two dynamic parameters suitable for closed-loop control, or at least likely to be optimized for a given application: the speed of the jet and the frequency of pulsation. Moreover the appearance of powerful pulsated microjets with MEMS (micro electro-mechanical systems) now allows considering a very good potential of integration in very constrained environments. Lastly, a last advantage offered by this type of actuator is that they do not disturb the flow when the system is not active.

This work, based on an analytical description of the flow, will be primarily experimental. We will use a hydrodynamic tunnel to make a thorough study of the interactions between the jets and the boundary layer. The test facilities will be primarily the PIV 15Hz and the Time-Resolved PIV (TR-PIV with 1kHz sampling frequency for the hydrodynamic flows) and visualization by Laser Induced Fluorescence (LIF). The effect of the JVGs on a separated flow will be also quantified using measurement of drag (global measurement). In parallel, validations out of wind tunnel experiments are envisaged in order to check that the parameters characterizing the efficiency of the actuators can be used on a broad range of Reynolds number. One can also run numerical simulations (CFD) to complement the experimental studies and help in the analysis of the flows. Through this PhD thesis, our objective is thus double. Initially, we want to find original physical criteria based on hydrodynamical stability and nonlinear evolution of the flow perturbations in the interaction JVG - Boundary layer. In a second time, we want to use them to choose the right dimensions and position of the JVG to control a generic separated flow (smoothly contoured ramp) and thus to propose an effective strategy of control of separated flows. This work will benefit from strong interactions with a project financed by the ANR (French National Research Agency) and the ADEME (French Association for Energy Savings). This project is directed by the PMMH laboratory with industrial partners like the teams of Research in Aerodynamics of Renault and PSA Peugeot-Citroen. It was proposed in response to the project call “Clean and Economic Vehicles” of the PREDIT in 2007. The student will benefit from a grant from the French Ministry of Research and Education. The student should speak English or French.

The subject of this plan is within the field of microfluidics. Recently, new strategies have been developed to manipulate very small volumes of liquids as required, for instance, in the manufacturing of low-cost portable devices called 'lab-on-a-chip'. These devices, which are of millimetric size and contain a large number of fluid paths/channels in the scale of microns, are intended to perform tasks of chemical and/or biological analysis (biotechnology). All of these techniques are still very new, and present investigations aim to describe the relevant physical mechanisms, as well as to find comparative advantages in order to propose the most suitable configurations appropriate for technological applications. The knowledge of the type of instabilities that may appear in these flows and how to control them is of fundamental importance to determine the feasibility of a given microfluidic design.

The research plan involves carrying out laboratory experiments, numerical simulations, and development of physical/mathematical models in order to study the dynamics of a specific fluid configuration relevant to the applications mentioned above. Experimental techniques involve using optical methods to measure fluid shapes, including thickness profiles, contact line geometry, slopes, contact angles, etc. Numerical simulations involve further development of existing routines, as well as of new computational methods.

Successful candidate will be enrolled in both UNCPBA and NJIT PhD programs. While the period which will be spent at each institution is flexible, we expect that a candidate will spend at least two years at each institution. During his/her stay at NJIT, a candidate will be fully supported (tuition + fellowship), while at UNCPBA his/her applications to appropriate fellowships will be supported by the University. Travel expenses may be also covered subject to availability of funds.