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Bio-based materials have strong hygrothermal behavior and phase change materials (PCMs) have high thermal inertia, but they have usually been studied separately in most research. In this paper, the hygrothermal behavior of a multilayer building envelope integrating hemp lime concrete (HLC) and PCM was investigated at experimental level. The envelope was flanked by a climate chamber and the laboratory ambient to imitate the outdoor and indoor environments, respectively. Four envelope configurations comprising a reference (without PCM) and three configurations with PCM (PCM placed on the outdoor and indoor side, in the middle of the envelope) were considered in order to study the effect of PCM and its position on the hygrothermal behavior of the envelope. The results showed that the PCM had a significant effect on the hygrothermal behavior of HLC, based on the high coupling between temperature and relative humidity. The characteristic time was considered to quantitatively evaluate temperature and relative humidity trends, and their value was increased with the participation of PCM. Moreover, PCM increased the heat store/release capacity linearly with its position. The closer the PCM was to the outdoor, the higher the heat store/release capacity and the lower the heating/cooling load from the envelope to the indoor environment. These phenomena were closely related to the PCM's temperature distribution and its corresponding specific heat capacity. Therefore, due to the envelope's thermal and hygric inertia on the indoor environment and the building's energy saving potential, it was recommended that the PCM be placed close to the outdoor side.

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The present paper investigates numerically the effect of an external magnetic field on heat transfer and entropy generation of Ag–MgO (50:50 vol%)/water hybrid nanofluid flow in a partially heated irregular ventilated cavity. A finite-volume FORTRAN code has been written to solve the governing partial differential equations. New empirical correlations specifically dedicated to predict the dynamic viscosity and the thermal conductivity of the considered hybrid nanofluid were employed. After validation of model, the analysis has been done for a wide range of Reynolds number (10 ≼ Re ≼ 600), Hartmann number (0 ≼ Ha ≼ 80) and total nanoparticle volume fraction (0 ≼ φ ≼ 0.02). The results are presented in terms of streamlines, isotherms and isentropic lines as well as the average Nusselt number (Num), the average entropy generation (Sgen,m) and the Bejan number (Beavg). The criterion ξ = Sgen,m/Num is adopted to discuss the thermal performances of the system. The results reveal that the intensification of the magnetic field tends to attenuate the heat transfer convection and to reduce the thickness of the thermal boundary layer, close to the active walls. Globally, adding nanoparticles to the base fluid improves the heat transfer but increases the total entropy generation.

Our study focuses on the thermal performance evaluation of a solar room built using a new bio-based composite wall coupled with a phase change material (PCM) layer during the cooling season in Nancy city France. This composite wall consists of a bio-based panel IBS-IZOLOX developed by the Belgium company ISOLHABITAT. The inner side of this bio-based composite wall should be coupled with a PCM layer in order to improve the thermal inertia of the room envelope. The results show that this system wall can improve significantly the thermal comfort performance of the passive solar room during the cooling season.

Numerical simulations were carried out to explain the behavior exhibited in experimental work on the dissolution process of silicon into a germanium melt. The experimental work utilized a material configuration similar to that used in the Liquid Phase Diffusion (LPD) and Melt-Replenishment Czochralski (Cz) growth systems. The numerical simulations were carried out under the assumption of 2D. The mathematical model equations were developed using Lattice Boltzmann Method (namely the BGK approximation was adopted). Measured concentration profiles and dissolution height from the samples processed with and without the application of magnetic field show that the amount of silicon transported into the melt is slightly higher in the samples processed under magnetic field, and there is a difference in dissolution interface shape indicating a change in flow structure. This change in flow structure was predicted by the present LB model. In the absence of magnetic field a flat stable interface is observed. In the presence of an applied field, however, the dissolution interface remains flat in the center but curves back into the source material near the edge of the wall. This indicates a far higher dissolution rate at the edge of the silicon source.

A solution based on the incorporation of a phase change material with ventilation tubes is proposed. This coupling is tested on a building material "concrete block" to increase the thermal inertia of the building walls. In the first part of the study, an experimental device is designed to compare the thermal response of different configurations depending on the condition of the tubes (open, closed, ventilated). The second part concerns a 3D numerical simulation. The results show potential solutions to ensure a large thermal inertia of a building.

This paper reports a numerical study of mixed convection heat transfer with entropy generation in a vented complex shape cavity filled with MWCNT−MgO (15:85 vol %) /water hybrid nanofluid. A hot source is placed at the mid potion of the inclined plate of the enclosure, while the rest of the rigid walls are adiabatic. A thermo-dependent correlations proposed by [12] for the dynamic viscosity and the thermal conductivity, especially developed for the considered fluid, are used. After validation of the model, the analysis has been done for a Reynolds numbers ranging from 10 to 600 and total nanoparticles volume fraction ranging from 0.0 to 0.02 using the finite volume method. The predicted results of streamlines, isotherms, isentropic lines, average Nusselt number, average entropy generation and average Bejan number are the main focus of interest in the present paper.

Natural convection of a magneto hydrodynamic nanofluid in a porous cavity in the presence of a magnetic field is investigated. The two vertical side walls are held isothermally at temperatures Th and Tc, while the horizontal walls of the outer cone are adiabatic. The governing equations obtained with the Boussinesq approximation are solved using Comsol Multiphysics finite element analysis and simulation software. Impact of Rayleigh number (Ra), Hartmann number (Ha) and nanofluid volume fraction (ϕ) are depicted. Results indicated that temperature gradient increases considerably with enhance of Ra and ϕ but it reduces with increases of Ha.

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Numerical study for the effect of an external magnetic field on the mixed convection of Al2O3–water Newtonian nanofluid in a right-angle vented trapezoidal cavity was performed using the finite volume method. The non-homogeneous Buongiorno model is applied for numerical description of the dynamic phenomena inside the cavity. The nanofluid, with low temperature and high concentration, enters the cavity through the upper open border, and is evacuated through opening placed at the right end of the bottom wall. The cavity is heated from the inclined wall, while the remainder walls are adiabatic and impermeable to both the base fluid and nanoparticles. After validation of the model, the analysis was carried out for a wide range of Hartmann number (0 ≼ Ha ≼ 100) and nanoparticles volume fraction (0 ≼ ϕ0 ≼ 0.06). The flow behavior as well as the temperature and nanoparticles distribution shows a particular sensitivity to the variations of both the Hartmann number and the nanofluid concentration. The domination of conduction mechanism at high Hartmann numbers reflects the significant effect of Brownian diffusion which tends to uniform the distribution of nanoparticles in the domain. The average Nusselt number which increases with the nanoparticles addition, depends strongly on the Hartmann number. Finally, a correlation predicting the average Nusselt number within such geometry as a function of the considered parameters is proposed.

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International audience; This paper exhibits the oscillatory characteristics of a free convective flow of nanofluids in horizontal concentric annuli of pilot dimensions to provide a mechanical solution against their particles settling which occurs by aggregation. These nanofluids are generated according to each class of particles that may exist with four types of industrial base liquids. Koo–Kleinstreuer semi-empirical models are used to generate databases of ideal suspended particles with Brownian motion. Meanwhile, Maxwell–Bruggeman and Kreiger–Dougherty semi-empirical models are used to incorporate the aggregation mechanism. A hybrid lattice Boltzmann/finite-difference approach is adopted to provide the space-time solutions. The accuracy of this numerical tool is inspected by providing over nine validations based on literature data. Hence, an improved flow pattern chart is accomplished to expand the open literature, depending on the flow nature of the base liquids in the annuli. Next, the oscillatory nature is fully revealed for each nanofluid processed. Following the frontiers toward the non-settling of aggregates, three main regimes are identified depending on the annulus size and the combination between ideal and aggregate mechanisms. Owing to this, a new settling chart is established to emerge the sheer limit of the annulus size for a non-settling process.

To solve the load shedding problem in the Comoros in a targeted rural area (Mbeni in the island of Ngazidja), I recommend the micro-grid system based on a renewable energy source with hydrogen storage. It has been almost two decades since the power generation company has been able to feed a large part of the Comorian population. This is due to the obsolescence of the production equipment of the electricity company, and the fact that the cost of the raw material (diesel) is very high compared to the cost of living of the Comorian population. The electricity company is struggling to cope with the increase in demand, which is about 5.1% per year. This increase in demand and the obsolescence of the equipment cause many load shedding. To combat this appalling plague, a feasibility study of the microgird system based on a renewable energy source with hydrogen storage seems entirely conceivable. In this article, solutions for electrifying rural areas in Comoros were designed and analyzed using Hybrid Renewable Energy Optimization (HOMER) with hydrogen storage.This system consists of:a photovoltaic generator, a wind turbine, an electrolyser, a fuel cell, a storage tank in the form of hydrogen.

Natural convection, in a shallow horizontal cavity filled with a nanofluid, is studied. The flow is driven by Lid driven convection (LDC). External applied constant heat fluxes on the bottom wall of the cavity is applied, whereas the vertical walls are subjected to variable heat fluxes. The nanofluid concentration is treated as heterogeneous mixtures with a weak solutal diffusivity. A modified formulation taking into account the physical properties (thermal conductivity, viscosity) versus on nanofluids type and concentration and the spatial heterogeneous concentration induced by the Soret effect is presented. The induced nanofluid heterogeneity can affect the heat transfer. The heat transfer increases with increase of the boundary motion. The analytical solution, based on parallel flow approximation, is found to be in good agreement with numerical solution. The existence of both natural and anti-natural flows is demonstrated. Indeed, the subcritical Rayleigh number for the onset of instability tends to disappear when the supercritical threshold is largely affected.

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The aim of this work is to develop a functional wood incorporating, in its surface, physical and chemical properties that meet society demand. For instance: fire resistance, magnetic electrical conduction (metal-wood particles), antibacterial reaction (copper-wood), anti-pollution (zeolite-wood), dry coloring, reflective effects (minerals-wood). As part of the research on wooden materials, the technique of “JAZOLTHOP” driving micrometric particles before combining them and moving in supersonic speeds was used in the framework of enriching a wooden substrate. Various tests were conducted on two wooden materials (fir and ash tree) submitted to four typologies of particles (steel shot, garnet, corundum and glass beads). The surfaces of the test samples were machined beforehand for a use of conventional smooth quality, thus defining a reference surface before incorporation. The enriched samples were characterized by using two optical techniques; firstly a surface technique through macroscopy Leica 110X ZP, then a volume technique through tomography. Subsequently, volume simulations (wood-inclusions) were implemented to study the thermal transfer. The obtained results showcase the existence of certain set conditions to reach the critical fluency of incorporation and to localize the enrichment on a parallel plan to the sample surface. The results show also the influence of particles concentration and the kind of the chosen wood on the final composite matrix/particle media.

In the present paper we aim to present the plasma spraying complexities in different levels with main focus on the powder injection parameters and some advances on the optimization of operating conditions toward process control. First the Lattice Boltzmann scrutiny of plasma jet and droplet impact characteristics on the target under the dispersion effects of injection parameters are presented. Second a Taguchi experimental design is conducted to explore the influence part and the interaction (if there) for five operating parameters in the spraying process. Finally, a test case for a ternary gas mixture is conducted to assess the conclusion drawn in the studies using the LB method and the experimental design. The results of the three methods are confronted together and discussed.

This work focuses on a horizontally ventilated cavity filled with air, heated on one side wall and cooled on the floor surface. Therefore, this study has been carried out for a convective loop induced for a fixed Rayleigh number Ra = 106 and horizontal ventilation (moderate Reynolds number Re = 100) where the injection is either in cooperating or opposing to the convective loop. The study undertaken concerns different opening position in order to analyze the energy efficiency of such ventilation and the corresponding indoor air quality. The results obtained indicate that the natural convection and the forced flow (ventilation) play an important role in the flow structure and the mixing ability, the heat exchange (cooling need) and the temperature comfort. The optimum ventilating position is a compromise in order to minimize the cooling demand, keep the mixing ability and reduce the temperature heterogeneity.

International audience; The lattice Boltzmann method based on the BGK model has been used to simulate laminar natural convection in a heated rectangular cavity on the uniform grid. The hydrodynamic and thermal fields are solved by using the double populations approach. A general benchmark has been carried out to show the effects of secondary parameters at their wide range. Excellent agreement is obtained by comparison with available literature

The thermal contact between layers plays a key role in the behaviour of composite particles (mechanofused) subjected to a high temperature jet (example of two layers metal/ceramic particles under plasma spraying). This work underlines the interest of considering a thermal contact resistance varying with the melting state of the two components along the full process. The computational model considers the time-dependent state of the particle during its flight with coupled transfers and solid/liquid/vapor phase changes. To cite this article: M. Bouneder et al., C. R. Mecanique 336 (2008).

An analytical approach of transient heat conduction in a two layered material, in finite dimensions within imperfect thermal contact, subjected to a moving Gaussian laser beam was achieved. The result of this study allows on the one hand an easy access to the distribution and the evolution of the temperature in both layers of the workpiece; on the other hand permits to clarify the influence of the contact quality on the temperature gap at the interface. The effect of a porous grannular deposit layer was also considered in this study. A design of electronic tracks by laser cladding was studied as an application example in the surface treatment area; this model can be also used to estimate the thermal contact resistance between layers.

International audience; A two-dimensional heat transfer model, extended phase change, is developed with an enthalpy formulation in order to predict the splat/substrate thermal story and its effects on plasma surface interaction. The model validated with respect to experimental results is used to estimate the early solidification of yttria stabilized zirconia splat deposited on a cooled substrate. Simulations quantify transfers in terms of some working parameters such that the splat thickness, the splat/substrate contact quality, the latent heat of solidification and the initial temperatures

With very few exceptions, the solid materials we use (metallic alloys, glasses, ceramics, plastics, etc.) have all undergone, at a crucial point in their history, the transition from the liquid state to the solid state. This change of state can be thought of as a major event since it determines, almost completely, the properties of the material: for instance, its microstructure (with or without grains), or its composition (with or without segregation). It depends on many parameters, such as the physical properties of the material, very different in metals, glasses, or plastics, and the exterior parameters of the solidification system (the type of oven or crucible, temperature gradient or cooling rate, speed of venting, an external action on the hydrodynamics of the fluid phase, etc.). There is also the manner in which these effects influence the phenomenon of solidification and the instantaneous shape of the interface, in general unstable, the absorption or rejection of a solute by the solid phase, and, finally, the practical properties of the material. This is indeed one of the major scientific challenges of our time, eager for advanced technologies and more and more discriminating about the quality of its materials. Historically, since antiquity, successive civilisations have always tried to perfect their materials. This firstly involved the quality of their weaponry, essential for their survival. Then, progressively, they laid more and more importance on the machinery needed for their agriculture, habitat and industry. Essentially empiric and often secret until the middle of the 20th century, the available knowledge on the physics of solidification has gradually become more and more rational, has become the subject of more and more publications, and has then become a discipline systematically taught at universities. However, there remain a number of mysteries still hidden behind unexplained experimental results, for which the technological consequences can be considerable, such as the number and size of the segregation channels in a metallic alloy made in a solidification oven, to give but one example. The underlying physics, multidisciplinary and highly complex, seems now sufficiently well understood to allow a precise formulation, even if several approximations often have to be judiciously used. However, this formulation seems to conceal all imaginable types of traps in systems of coupled, strongly non-linear equations. The last twenty years have, by giving birth to powerful numerical simulation methods, even although sometimes very heavy, opened completely new perspectives in the search for the understanding of solidification. That this problem covers many coupled disciplines no longer poses a problem. Thus, the coupling between the hydrodynamics of the liquid phase and the mechanism of solidification itself seems to be better taken into account. And, as a consequence, various contributions try to act on the parameters governing fluid motion, showing the effects of exterior forces (reduced gravity or an applied magnetic field, for example), with the aim of controlling such and such a property of the material in fine. However, numerical simulation, in turn, presents its own difficulties and challenges, such as following the spatial-temporal variation of segregation in the presence of a columnar structure, or even the optimisation of algorithms for a fixed calculating power. And one remarks that, at least at present, these new techniques require, for their own validation, new, and high precision, experimental results. It seems that, from now on, the research strategies are highly influenced by the existence of numerical simulations, the experiment becoming more and more an argument for validation, and computation replacing repeated experiments, whenever the numerical method has been well validated, notably for dimensioning equipment, and for optimising industrial processes.

Three-dimensional calculations have been done to simulate the onset of convective motion in ternary nondilute solution under phase transition conditions. The process is considered for Rayleigh number in the range [ 1 × 10 3 , 1.4 × 10 4 ] , where subcritical convective motion with hexagonal flow pattern is identified. The results are in good agreement with the linear and finite amplitude theory of hydrodynamics instability. To cite this article: V.V. Kolmychkov et al., C. R. Mecanique 333 (2005).

Resume L'investigation des instabilites convectives pour des fluides a faible nombre de Prandtl a fait l'objet de plusieurs etudes. Il s'agit ici de realiser une extension a un bain fondu a surface libre ou rigide en changement de phase et de construire le diagramme de bifurcation correspondant. Quelques situations de controle a travers la chaleur latente et l'ecart des conductivites solide/liquide sont considerees. L'approche de resolution adoptee est basee sur une methode de localisation du front ayant montre une tres bonne aptitude a la description des regimes convectifs en presence de changement de phase pour une configuration verticale confinee. Pour citer cet article : E.A. Semma et al., C. R. Mecanique 331 (2003).

Direct numerical simulations (DNS) for axisymmetric plasma jet are developed to investigate particle plasma spraying process. In this paper we study the plasma jet and we focus mainly on the plasma-particle ex-changes. Finite element analysis employing COMSOL Multiphysics software is used in this simulation. Finally, comparisons are made with the numerically observed particle Nusselt?s numbers and theoretically predicted Nusselt?s numbers based on the Ranz-Marshall correlation. The results agree well with those obtained previously.

This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s), is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

The present study aims to use the concept of entropy generation in order to study numerically the flow and the interaction of multiple jets. Several configurations of a single jet surrounded by equidistant 3, 5, 7 and 9 circumferential jets have been studied. The turbulent incompressible Navier-Stokes equations have been solved numerically using the commercial computational fluid dynamics code Fluent. The standard k-e model has been selected to assess the eddy viscosity. The domain has been reduced to a quarter of the geometry due to symmetry. Results for axial and radial velocities have been compared with experimental measurements from the literature. Furthermore, additional results involving entropy generation rate have been presented and discussed.

Numerical analysis has been performed on the motion of a spherical particle injected into high temperature thermal plasma flows in order to disclose the mechanisms of heat transfer enhancement and to establish reliable correlations for heat transfer between the plasma gas and the particle. In terms of fluid dynamics occurring, the Navier-Stokes equations were solved for Ar-H 2 mixture plasma gas in a two-dimensional system by finite element method (FEM). Computational simulation was undertaken to model the correlations for fine spherical particles in Ar 25%-H 2 75% as plasma gas from 1100 to 9100 K at atmospheric pressure. Our results reveal the general consensus of Nusselt number, followed by increasing deviations as the temperature increases. Additionally, a comparison between our data and the predictions of other published correlations are given.

Purpose – The purpose of this paper is to present a 2D numerical simulation of natural convection and phase‐change of succinonitrile in a horizontal Bridgman apparatus. Three different heat transfer mechanisms are specifically studied: no growth, solidification and melting.Design/methodology/approach – The analysis is carried out with a preexisting thermally coupled fixed‐mesh finite element formulation for generalized phase‐change problems.Findings – In the three cases analyzed, the predicted steady‐state liquid‐solid interfaces are found to be highly curved due to the development of a primary shallow cell driven by the imposed furnace temperature gradient. In the no growth case, the heating and cooling jackets remain fixed and, therefore, a stagnant liquid‐solid interface is obtained. On the other hand, the phase transformation in the solidification and melting cases is, respectively, controlled by the forward and backward movement of the jackets. In these last two growth conditions, the permanent regim...

International audience; A numerical simulation study, using finite element method, was carried out to examine the temperature and concentration fields in the dissolution process of silicon into germanium melt. This work utilized a simplified configuration which may be considered to be similar material configuration to that used in the Vertical Bridgman growth methods. The concentration profile for the Si-Ge sample processed using this technique shows increasing transport silicon into the melt with time, moreover, a flat stable interface is observed. The mass and momentum equations for fluid flow, the energy and the solute mass transport were numerically solved. Results showed good agreements with experiments.

International audience; The coating of surfaces by plasma spraying is an important manufacturing process with many industrial applications. In the last several decades, numerical modeling of plasma spraying processes has met with considerable attention [1,2,3]. That is in order to well understand the complex phenomena the plasma spray involves, for economic constraints and to well predict the plasma-inflight-particles exchanges since this affects directly the coating formability and microstructure. This study deals with the investigation of plasma jets using an axisymmetric LB thermal model. Plasma jets have been very successful in many applications (such as spraying, cutting, welding,...). The excellent choice of high performance plasma gases and spraying materials has been the subject of several experimental and numerical efforts. An excellent choice will be the response of efficient numerical studies and the results of experimental tests. Plasma jets are high temperature flows (>8000K). Therefore, all diffusion parameters involved in conservation equations are temperature dependent. In the following, we present a plasma jet investigation in an axisymmetric LBM (Jian's model [4]). In the context of our knowledge, it is the first attempt to tackle this field by using the LBM. Further reading on solution procedure, the model implementation and assumptions may be found in [5,6]

Over the past two decades, there have been enormous advances in lat- tice Boltzmann (LB) numerical simulation and modelling. The lattice Boltzmann method has become a practical and promising tool for many fluid problems. A majority of recent studies have relied on numerical computations of isothermal flows. However, much less efforts have been devoted to complex thermal flows, such as flows in porous media subjected to external magnetic force, flows with temperature-dependent properties. In this paper, an overview is made based on some accomplishments in these numerical endeavours. Along with the paper's sections, the state-of-the-art trend and the LBM advances in modelling and in com- putational aspects for specific classes of problems of major interest will be fully touched on. Concluding remarks are given and the axis of our future studies will be traced. AMS subject classifications: 76M28, 70K50, 76S05, 82D10

International audience; Lattice Boltzmann (LB) method is considered versus classical discretisation approaches to solve the problem of heat and fluid flow. The work considers situations with symmetry breaking for low Prandtl number fluids flowing in enclosures interesting directional solidification industry. The computed results demonstrate a good LB method's ability to captivate flow bifurcation thresholds. Particularly cavities exhibiting bifurcation sequences are considered and results are consistent with prior observations

International audience; In this paper, we propose a hybrid method coupling a Lattice Boltzmann Method (LBM) and a Finite Volume Method (FVM), to study melting and solidification problems. The LBM is used to determine the dynamics field while the FVM is applied to discretize the energy equation. This model is validated by comparison to available literature results concerning a square cavity heated without phase change then for the melting of Gallium in an enclosure commonly used as benchmark test case

International audience; For simulating flows in a porous medium, a numerical tool based on the Lattice Boltzmann Method (LBM) is developed with regards to the classical D2Q9 model. A short description of this model is presented. This technique, applied to two-dimensional configurations, indicates its ability to simulate phenomena of heat and mass transfer. The numerical study is extended to estimate physical parameters that characterize porous materials, like the so-called Effective Thermal Conductivity (ETC) which is of our interest in this paper. Obtained results are compared with those which could be found analytically and by theoretical models. Finally, a porous medium is considered to find its ETC.

Thermosolutal natural convection induced in a vertical porous layer heated and salted with uniform fluxes is studied analytically and numerically. The study is focused on a specific case where the separation coefficient is identical to the ratio of buoyancy forces. Analytical results, describing both pseudo-conductive and boundary layer regimes, are discussed. Specific behaviour, corresponding to this particular situation, is presented. To cite this article: M. Er-Raki et al., C. R. Mecanique 336 (2008).

International audience; The control of a process dealing with heat pipe exploitation needs the thermal analysis of the evaporation-condensation cycle and noticeably the imposed external conditions (in instance modeling the heating). In this work a numerical model has been developed to describe the local coupling near the liquid/vapour interface. Simulations exhibits and quantify the response of the capillary motion to the thermal conditions.

International audience; This paper presents a numerical study of transient heat transfer and phase change of a thermal spray coating problem. The early solidification of yttria stabilized zirconia splat deposited on a cooled substrate is considered. These phenomena are quantified in terms of some working parameters such that: the splat thickness, the splat/substrate contact quality, the latent heat of solidification and the initial temperatures. A two-dimensional heat transfer model, extended phase change, is developed with an enthalpy formulation in order to predict the splat/substrate thermal story and its effects on plasma surface interaction. The results are in good agreement with an experimental one for the case of a nickel splatting on an alumina substrate.

The present work uses the Lattice Boltzmann method for solving solid/liquid phase change problems. The computed results demonstrate a good agreement with the existing benchmark solution for natural convection and with the experimental solution for solid/liquid interface interacting with the flow field. To cite this article: E. Semma et al., C. R. Mecanique 335 (2007).

PurposeThe objective of the present study is to investigate numerically the effects of thermal and buoyancy forces on both upward flow (UF) and downward flow (DF) of air in a vertical parallel‐plates channel. The plates are wetted by a thin liquid water film and maintained at a constant temperature lower than that of the air entering the channel.Design/methodology/approachThe solution of the elliptical PDE modeling the flow field is based on the finite volume method.FindingsResults show that buoyancy forces have an important effect on heat and mass transfers. Cases with evaporation and condensation have been investigated for both UF and DF. It has been established that the heat transfer associated with these phase changes (i.e. latent heat transfer) may be more or less important compared with sensible heat transfer. The importance of these transfers depends on the temperature and humidity conditions. On the other hand, flow reversal has been predicted for an UF with a relatively high temperature difference between the incoming air and the walls.Originality/valueContrary to most studies in channel heat and mass transfer with phase change, the mathematical model considers the full elliptical Navier‐Stokes equations. This allows one to compute situations of flow reversal.

International audience; This study aims to investigate turbulent plasma flow over spheroidal particles using the lattice Boltzmann (LB) method. A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields. Along with the calculation process a conversion procedure is made between the LB and the physical unit systems, so that thermo-physical properties variation is fully accounted for and the convergence is checked in physical space. The configuration domain and the boundary condition treatment are selected based on the most cited studies in order to illustrate a realistic situation. The jet morphology analysis gives credible results by comparison with commonly published works. A second Lagrangian model has been developed to investigate the plasma-particles exchange during its in-flight. The tracking of the μ-sized particles allows concluding that our results are in sufficient agreement with those of the Jets&Poudres code and that the LB method account well for plasma jet physics which affects directly the particles in-flights.