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Seyed Ali Hosseini, Pierre Boivin, Dominique Thévenin, Ilya Karlin. Lattice Boltzmann methods for combustion applications. Progress in Energy and Combustion Science, 2024, 102, pp.101140. ⟨10.1016/j.pecs.2023.101140⟩. ⟨hal-04412786⟩ Plus de détails...
The lattice Boltzmann method, after close to thirty years of presence in computational fluid dynamics has turned into a versatile, efficient and quite popular numerical tool for fluid flow simulations. The lattice Boltzmann method owes its popularity in the past decade to its efficiency, low numerical dissipation and simplicity of its algorithm. Progress in recent years has opened the door for yet another very challenging area of application: Combustion simulations. Combustion is known to be a challenge for numerical tools due to, among many others, the large number of variables and scales both in time and space, leading to a stiff multi-scale problem. In the present work we present a comprehensive overview of models and strategies developed in the past years to model combustion with the lattice Boltzmann method and discuss some of the most recent applications, remaining challenges and prospects.
Seyed Ali Hosseini, Pierre Boivin, Dominique Thévenin, Ilya Karlin. Lattice Boltzmann methods for combustion applications. Progress in Energy and Combustion Science, 2024, 102, pp.101140. ⟨10.1016/j.pecs.2023.101140⟩. ⟨hal-04412786⟩
Journal: Progress in Energy and Combustion Science
Uwe Ehrenstein. Generalization to differential–algebraic equations of Lyapunov–Schmidt type reduction at Hopf bifurcations. Communications in Nonlinear Science and Numerical Simulation, 2024, 131, pp.107833. ⟨10.1016/j.cnsns.2024.107833⟩. ⟨hal-04408097⟩ Plus de détails...
The Lyapunov-Schmidt procedure, a well-known and powerful tool for the local reduction of nonlinear systems at bifurcation points or for ordinary differential equations (ODEs) at Hopf bifurcations, is extended to the context of strangeness-free differential-algebraic equations (DAEs), by generalizing the comprehensive presentation of the method for ODEs provided in the classical textbook by Golubitsky and Schaeffer [Applied mathematical sciences, {\bf 51}, Springer (1985)]. The appropriate setting in the context of DAEs at Hopf bifurcations is first detailed, introducing suitable operators and addressing the question of appropriate numerical algorithms for their construction as well. The different steps of the reduction procedure are carefully reinterpreted in the light of the DAE context and detailed formulas are provided for systematic and rational construction of the bifurcating local periodic solution, whose stability is shown, likely to the ODE context, to be predicted by the reduced equations. As an illustrative example, a classical DAE model for an electric power system is considered, exhibiting both supercritical and subcritical Hopf bifurcations, demonstrating the prediction capability of the reduced system with regard to the global dynamics.
Uwe Ehrenstein. Generalization to differential–algebraic equations of Lyapunov–Schmidt type reduction at Hopf bifurcations. Communications in Nonlinear Science and Numerical Simulation, 2024, 131, pp.107833. ⟨10.1016/j.cnsns.2024.107833⟩. ⟨hal-04408097⟩
Journal: Communications in Nonlinear Science and Numerical Simulation
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Large eddy simulation of fire-induced flows using Lattice-Boltzmann methods. International Journal of Thermal Sciences, 2024, 197, pp.108801. ⟨10.1016/j.ijthermalsci.2023.108801⟩. ⟨hal-04338538⟩ Plus de détails...
Large-eddy simulations (LES) of the near-field region of large-scale fire plumes are performed for the first time with a pressure-based Lattice Boltzmann method (LBM) with low-Mach number approximation. Two scenarios are considered: the large-scale non-reactive helium plume and the 1 m methane pool fire, both investigated experimentally at Sandia. In the second scenario, a simplified modeling of the combustion and radiation processes is introduced involving a one-step irreversible reaction eddydissipation concept-based combustion model and a radiant fraction model, respectively. In both scenarios, a quantitative agreement is observed with the experimental data and model predictions are consistent with previouslypublished numerical studies. Our simulations demonstrate the computational efficiency of the proposed LBM solver to tackle fire-induced flows, suggesting that LBMs are a good alternative candidate for the modeling of fire-related problems.
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Large eddy simulation of fire-induced flows using Lattice-Boltzmann methods. International Journal of Thermal Sciences, 2024, 197, pp.108801. ⟨10.1016/j.ijthermalsci.2023.108801⟩. ⟨hal-04338538⟩
Journal: International Journal of Thermal Sciences
Heni Dallagi, Nassim Ait-Mouheb, Audrey Soric, Olivier Boiron. Simulation of the flow characteristics of a labyrinth milli-channel used in drip irrigation. Biosystems Engineering, 2024, 239, pp.114-129. ⟨10.1016/j.biosystemseng.2024.02.004⟩. ⟨hal-04479285⟩ Plus de détails...
Water scarcity is a global concern, with irrigation of food crops contributing significantly to freshwater depletion. Drip irrigation technology reduces water consumption but faces issues like clogging in narrow discharge sections, diminishing efficiency, and increasing costs. Accurate prediction of flow characteristics and understanding pa- rameters affecting biofilm growth and particle deposition is crucial for effective anti-clogging strategies. Computational fluid dynamics (CFD) using turbulence models can be a valuable tool. This study evaluated the accuracy and efficiency of different turbulence models (standard k-ε, Reynolds Stress Model, and Large Eddy Simulation) in predicting the flow characteristics of a commercial emitter in a drip irrigation system. Results showed the standard k-ε model as a preferred choice for simulating mean flow characteristics and emitter discharge due to its balance between accuracy and computational efficiency. However, the Large Eddy Simu- lation model provided the most accurate results, considering the emitter discharge, unsteady flow behavior, wall shear stress distribution, and oscillatory index, despite requiring more computational resources. This model is valuable for understanding hydrodynamic effects on emitter clogging. The study also investigated the impact of velocity fluctuations, wall shear stress, and oscillatory shear index on biofilm growth and deposition in the emitter. Low shear stress in inlet and return zones reduced self-cleaning ability, leading to particle and micro- organism attachment. Maintaining appropriate wall shear stress values in other regions proved crucial for improving anti-clogging ability. High oscillatory shear index values enhanced mass transfer, nutrient mixing, diffusion within the biofilm, and self-cleaning capacity. In summary, this study greatly enhances our under- standing of how flow dynamics and biofilm management impact drip irrigation systems. It provides practical insights for engineers and practitioners, aiding in the creation of more efficient and clog-resistant systems. By optimizing these dynamics and strategies, this research promotes sustainable water use in agriculture, while also minimizing maintenance costs and maximizing crop yields.
Heni Dallagi, Nassim Ait-Mouheb, Audrey Soric, Olivier Boiron. Simulation of the flow characteristics of a labyrinth milli-channel used in drip irrigation. Biosystems Engineering, 2024, 239, pp.114-129. ⟨10.1016/j.biosystemseng.2024.02.004⟩. ⟨hal-04479285⟩
Raffael Düll, Hugo Bufferand, Eric Serre, Guido Ciraolo, Virginia Quadri, et al.. Introducing electromagnetic effects in Soledge3X. Contributions to Plasma Physics, 2024, pp.e202300147. ⟨10.1002/ctpp.202300147⟩. ⟨hal-04474339⟩ Plus de détails...
In the pedestal region, electromagnetic effects affect the evolution of micro‐instabilities and plasma turbulence. The transport code Soledge3X developed by the CEA offers an efficient framework for turbulent 3D simulation on an electrostatic model with a fixed magnetic field. The physical accuracy of the model is improved with electromagnetic induction, driven by the local value of the parallel component of the electromagnetic vector potential , known from Ampère's law. It is solved implicitly in a coupled system with the vorticity equation on the electric potential . The consequence is a basic electromagnetic behavior in the form of shear Alfvén waves. A finite electron mass prevents unphysical speeds but requires solving for the time evolution of the parallel current density in the generalized Ohm's law. This term can be analytically included with little computational overhead in the system on and and improves its numerical condition, facilitating the iterative solving procedure. Simulations on a periodic slab case let us observe the predicted bifurcation of the wave propagation speed between the Alfvén wave and the electron thermal wave speeds for varying perpendicular wavenumbers. The first results on a circular geometry with a limiter attest to the feasibility of turbulent electromagnetic scenarios.
Raffael Düll, Hugo Bufferand, Eric Serre, Guido Ciraolo, Virginia Quadri, et al.. Introducing electromagnetic effects in Soledge3X. Contributions to Plasma Physics, 2024, pp.e202300147. ⟨10.1002/ctpp.202300147⟩. ⟨hal-04474339⟩
Frédéric Schwander, Eric Serre, Hugo Bufferand, Guido Ciraolo, Philippe Ghendrih. Global fluid simulations of edge plasma turbulence in tokamaks: a review. Computers and Fluids, 2024, 270, pp.106141. ⟨10.1016/j.compfluid.2023.106141⟩. ⟨hal-04352255⟩ Plus de détails...
With ITER, the largest tokamak ever built, and the growing number of fusion energy startups in the world, the need for numerical simulations has never been more crucial to progress towards the successful operation of fusion reactors. From fundamental plasma physics to engineering, a hierarchy of models exists from high-fidelity (gyro-)kinetic models in (5D) 6D to 0D fluid transport models. In this paper, we review the state-of-the-art of 3D turbulence fluid simulations in edge tokamak configurations. The widely used drift-reduced Braginskii equations are introduced together with the dedicated boundary conditions modelling plasma wall interactions. If until recently most of the models were focused on electrostatic turbulence driven by interchange-like instabilities, in recent years models have incorporated electromagnetic effects allowing fluctuations of the magnetic field. Specific features of the edge plasma configurations, which make these equations specially challenging to resolve and stressful for the numerical methods, are detailed. In particular, the strong anisotropy of the flow as well as the complex geometric characteristics lead to the development of dedicated discretization schemes and meshing, which are implemented in state-of-the-art codes reviewed here. It appears that the latter can be differentiated by their mesh construction as well by the manner in which they handle parallel gradients (aligned or not along the magnetic field). The review shows that no consensus on the optimal combination between meshing and discretization schemes, if it exists, has been found. Finally, examples of recent achievements show that 3D turbulence simulations of medium-sized tokamaks are currently achievable, but that ITERsize tokamaks and thermonuclear plasmas still require significant progress.
Frédéric Schwander, Eric Serre, Hugo Bufferand, Guido Ciraolo, Philippe Ghendrih. Global fluid simulations of edge plasma turbulence in tokamaks: a review. Computers and Fluids, 2024, 270, pp.106141. ⟨10.1016/j.compfluid.2023.106141⟩. ⟨hal-04352255⟩
Aymeric Fabien, Guillaume Lefebvre, Elisabeth Badens, Brice Calvignac, Damien Chaudanson, et al.. Contact angle of ethanol, water, and their mixtures on stainless steel surfaces in dense carbon dioxide. Journal of Colloid and Interface Science, 2024, 655, pp.535-545. ⟨10.1016/j.jcis.2023.10.163⟩. ⟨hal-04316090⟩ Plus de détails...
Hypothesis Contact angle can be a key parameter in chemical engineering. However, the development and the optimization of numerous processes using supercritical CO2, considered as environmentally friendly, requires new measurements under dense CO2 atmosphere. Besides, the influence of the roughness or the wetting regime on the contact angle is known at ambient conditions but remains to be discussed for systems under high pressure. Experimental Contact angle measurements of ethanol, water, and their mixtures, with ethanol mass fractions ranging from 0.25 to 0.75, on two stainless steels in saturated CO2 at pressures ranging from 0.1 MPa to 15.1 MPa, and at 313 K and 333 K were carried out in a set-up improving mass transfer between the studied liquid and the continuous fluid phase. Stainless steel surfaces have been characterized by atomic force and scanning electron microscopies allowing the application of the Wenzel equation. Findings Ethanol wetted totally both stainless steels while contact angles of all other liquids were increased by the rise of pressure, with contact angles up to 128 ° for water at 15.1 MPa. Trapped bubbles were observed at the solid/liquid interface and the bubble formation is discussed. Furthermore, the potential influence of bubble presence on the wetting regime is prospected through the question: could the pressure rise modify the wetting regime?
Aymeric Fabien, Guillaume Lefebvre, Elisabeth Badens, Brice Calvignac, Damien Chaudanson, et al.. Contact angle of ethanol, water, and their mixtures on stainless steel surfaces in dense carbon dioxide. Journal of Colloid and Interface Science, 2024, 655, pp.535-545. ⟨10.1016/j.jcis.2023.10.163⟩. ⟨hal-04316090⟩
V Puthumana, Paul G. Chen, M Leonetti, R Lasserre, M Jaeger. Assessment of coupled bilayer-cytoskeleton modelling strategy for red blood cell dynamics in flow. Journal of Fluid Mechanics, 2024, 979, pp.A44. ⟨10.1017/jfm.2023.1092⟩. ⟨hal-04409136⟩ Plus de détails...
The red blood cell (RBC) membrane is composed of a lipid bilayer and a cytoskeleton interconnected by protein junction complexes, allowing for potential sliding between the lipid bilayer and the cytoskeleton. Despite this biological reality, it is most often modelled as a single-layer model, a hyperelastic capsule or a fluid vesicle. Another approach involves incorporating the membrane's composite structure using double layers, where one layer represents the lipid bilayer and the other represents the cytoskeleton. In this paper, we computationally assess the various modelling strategies by analysing RBC behaviour in extensional flow and four distinct regimes that simulate RBC dynamics in shear flow. The proposed double-layer strategies, such as the vesicle--capsule and capsule--capsule models, account for the fluidity and surface incompressibility of the lipid bilayer in different ways. Our findings demonstrate that introducing sliding between the layers offers the cytoskeleton a considerable degree of freedom to alleviate its elastic stresses, resulting in a significant increase in RBC elongation. Surprisingly, our study reveals that the membrane modelling strategy for RBCs holds greater importance than the choice of the cytoskeleton's reference shape. These results highlight the inadequacy of considering mechanical properties alone and emphasise the need for careful integration of these properties. Furthermore, our findings fortuitously uncover a novel indicator for determining the appropriate stress-free shape of the cytoskeleton.
V Puthumana, Paul G. Chen, M Leonetti, R Lasserre, M Jaeger. Assessment of coupled bilayer-cytoskeleton modelling strategy for red blood cell dynamics in flow. Journal of Fluid Mechanics, 2024, 979, pp.A44. ⟨10.1017/jfm.2023.1092⟩. ⟨hal-04409136⟩
Franck Corset, Mitra Fouladirad, Christian Paroissin. Imperfect and worse than old maintenances for a gamma degradation process. Applied Stochastic Models in Business and Industry, In press, ⟨10.1002/asmb.2849⟩. ⟨hal-04462980⟩ Plus de détails...
This article considers a condition‐based maintenance for a system subject to deterioration. The deterioration is modeled by a non‐homogeneous gamma process, more precisely the gamma process and the preventive maintenance are imperfect or worse than old. The corrective maintenance actions are as good as new. The maintenance efficiency or non‐efficiency parameters as well as the deterioration parameters are considered to be unknown. The monitoring data under consideration give indirect information on the maintenance parameters. Therefore, an expected maximum algorithm is applied for parameter estimation.
Franck Corset, Mitra Fouladirad, Christian Paroissin. Imperfect and worse than old maintenances for a gamma degradation process. Applied Stochastic Models in Business and Industry, In press, ⟨10.1002/asmb.2849⟩. ⟨hal-04462980⟩
Journal: Applied Stochastic Models in Business and Industry
Jingqi Zhang, Mitra Fouladirad, Nikolaos Limnios. A Semi-Markov Model with Geometric Renewal Processes. Methodology and Computing in Applied Probability, 2023, 25 (4), pp.85. ⟨10.1007/s11009-023-10060-z⟩. ⟨hal-04429456⟩ Plus de détails...
We consider a repairable system modeled by a semi-Markov process (SMP), where we include a geometric renewal process for system degradation upon repair, and replacement strategies for non-repairable failure or upon N repairs. First Pérez-Ocón and Torres-Castro studied this system (Pérez-Ocón and Torres-Castro in Appl Stoch Model Bus Ind 18(2):157–170, 2002) and proposed availability calculation using the Laplace Transform. In our work, we consider an extended state space for up and down times separately. This allows us to leverage the standard theory for SMP to obtain all reliability related measurements such as reliability, availability (point and steady-state), mean times and rate of occurrence of failures of the system with general initial law. We proceed with a convolution algebra, which allows us to obtain final closed form formulas for the above measurements. Finally, numerical examples are given to illustrate the methodology.
Jingqi Zhang, Mitra Fouladirad, Nikolaos Limnios. A Semi-Markov Model with Geometric Renewal Processes. Methodology and Computing in Applied Probability, 2023, 25 (4), pp.85. ⟨10.1007/s11009-023-10060-z⟩. ⟨hal-04429456⟩
Journal: Methodology and Computing in Applied Probability