| 1. |
- Bellomo, Nicola, 1943, et al.
(author)
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The generalized-kinetics-based equilibrium distribution function for composite particles
- 2003
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In: Comptes Rendus - Mecanique. - : Elsevier Science B.V., Amsterdam.. - 1631-0721 .- 1873-7234. ; 331:7, s. 461-467
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Journal article (peer-reviewed)abstract
- This work is devoted to the equilibrium distribution function for a fluid of mutually non-interacting identical composite point particles in three-dimensional physical space. The distribution function is derived within the generalized-kinetics (GK) vision from the proposed probabilistic model based on quantum-mechanical bosons and fermions. The first GK advantage is that the derivation does not involve any assumption on the interpolation between bosons and fermions whereas the resulting function provides this interpolation. The second GK advantage is that composons, the particles described with the GK-based distribution function, are considerably less schematic and more consistent physically than quons. Composons correspond to a specific case of Isakov's general q-commutation relation involving an infinite number of the q-coefficients. Connection of the composon concept to previous results in the literature is pointed out. A few directions for future research on the topic are formulated. The results of the work can be used in the composite-particle fluid problems where the Maxwell–Boltzmann description is not valid, for instance, in dense populations of not too massive point-like particles of a complex, composite nature at not too high temperatures. FRENCH: Ce travail s'intéresse à la fonction de distribution d'équilibre pour un fluide mutuellement non agissant, composé de particules points dans un espace de dimension trois. La fonction de distribution provient, d'un point de vue de CG, d'un modèle probabiliste issu de la mécanique quantique des fermions et des bosons. Le premier avantage de CG est que la dérivation ne nécessite aucune hypothèse sur l'interpolation entre les bosons et les fermions alors que la fonction résultante fournit cette interpolation. Le second est que les composons, les particules décrites par ce procédé sont considérablement moins schématiques et plus consistantes, physiquement, que les quons. Les composons correspondent à un cas particulier de la relation générale de q-commutation d'Isakov, pour un nombre infini de q-coefficients. Les résultats antérieurs liés au concept de composon sont signalés et quelques directions de recherches futures sont proposées. Les résultats de ce travail peuvent servir pour l'étude de fluides composés, où la description Maxwell–Boltzmann n'est pas valable, par exemple, pour une dense population de particules, pas trop lourdes et a des températures pas trop élevées, et d'une comoposition de nature complexe.
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| 2. |
- Kozlov, Vladimir, 1954-, et al.
(author)
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On the fundamental sloshing frequency in the ice-fishing problem
- 2002
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In: Comptes rendus. Mecanique. - 1631-0721 .- 1873-7234. ; 330:11, s. 723-728
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Journal article (peer-reviewed)abstract
- The sloshing problem is considered in a half-space covered by a rigid dock with apertures. The dependence of the fundamental sloshing frequency on the shape of the free surface region is studied. It is proved that the inequality holds between the fundamental eigenvalues corresponding to two different regions if some conditions are fulfilled. These conditions are verified for particular classes of regions of a fixed area in order to demonstrate that the disk yields the maximum of the fundamental eigenvalue for each of these classes. On the other hand, examples of regions are constructed for which the fundamental eigenfrequency is larger than that for the circular aperture of the same area and even as large as one wishes.
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| 3. |
- Kozlov, Vladimir, 1954-, et al.
(author)
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On two-dimensional water waves in a canal
- 2003
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In: Comptes rendus. Mecanique. - 1631-0721 .- 1873-7234. ; 331:7, s. 489-494
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Journal article (peer-reviewed)abstract
- This Note deals with an eigenvalue problem that contains a spectral parameter in a boundary condition. The problem for the two-dimensional Laplace equation describes free, time-harmonic water waves in a canal having uniform cross-section and bounded from above by a horizontal free surface. It is shown that there exists a domain for which at least one of eigenfunctions has a nodal line with both ends on the free surface. Since Kuttler essentially used the non-existence of such nodal lines in his proof of simplicity of the fundamental sloshing eigenvalue in the two-dimensional case, we propose a new variational principle for demonstrating this latter fact. ⌐ 2003 AcadΘmie des sciences.
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| 4. |
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| 5. |
- Beaubert, Francois, et al.
(author)
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Design of a device to induce swirling flow in pipes : A rational approach
- 2015
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In: Comptes rendus. Mecanique. - : Elsevier BV. - 1631-0721 .- 1873-7234. ; 343:1, s. 1-12
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Journal article (peer-reviewed)abstract
- In this study, a rational approach is proposed to design a device for inducing swirling flow in heat exchanger pipes, for improved efficiency in the laminar regime. First, 2D computational fluid dynamics results lead to select, among four profiles, the blade profile with the most favorable lift to drag ratio. Then, the fluid flow in the swirler made with the selected blade profile is simulated in 3D, for Reynolds numbers ranging from 50 to 1600. Based on the simulation results, an analytic approximation of the evolution of the tangential fluid velocity is proposed as a function of the Reynolds number.
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| 6. |
- Biciusca, Tonino, et al.
(author)
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Simulation of liquid-vapour phase separation on GPUs using Lattice Boltzmann models with off-lattice velocity sets
- 2015
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In: Comptes rendus. Mecanique. - : ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER. - 1631-0721 .- 1873-7234. ; 343:10-11, s. 580-588
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Journal article (peer-reviewed)abstract
- We use a two-dimensional Lattice Boltzmann model to investigate the liquid-vapour phase separation in an isothermal van der Waals fluid. The model is based on the expansion of the distribution function up to the third order in terms of Hermite polynomials. In two dimensions, this model is an off-lattice one and has 16 velocities. The Corner Transport Upwind Scheme is used to evolve the corresponding distribution functions on a square lattice. The resulting code allows one to follow the liquid-vapour phase separation on lattices up to 4096 x 4096 nodes using a Tesla M2090 Graphics Processing Unit. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
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| 7. |
- Cirillo, Emilio N. M., et al.
(author)
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Can cooperation slow down emergency evacuations?
- 2012
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In: Comptes rendus. Mecanique. - : Elsevier. - 1631-0721 .- 1873-7234. ; 340:9, s. 625-628
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Journal article (peer-reviewed)abstract
- We study the motion of pedestrians through obscure corridors where the lack of visibility hides the precise position of the exits. Using a lattice model, we explore the effects of cooperation on the overall exit flux (evacuation rate). More precisely, we study the effect of the buddying threshold (of no–exclusion per site) on the dynamics of the crowd. In some cases, we note that if the evacuees tend to cooperate and act altruistically, then their collective action tends to favor the occurrence of disasters.
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| 8. |
- Cirillo, Emilio N.M., et al.
(author)
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Does communication enhance pedestrians transport in the dark?
- 2016
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In: Comptes rendus. Mecanique. - : Elsevier. - 1631-0721 .- 1873-7234. ; 344:1, s. 19-23
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Journal article (peer-reviewed)abstract
- We study the motion of pedestrians through an obscure tunnel where the lack of visibility hides the exits. Using a lattice model, we explore the effects of communication on the effective transport properties of the crowd of pedestrians. More precisely, we study the effect of two thresholds on the structure of the effective nonlinear diffusion coefficient. One threshold models pedestrian communication efficiency in the dark, while the other one describes the tunnel capacity. Essentially, we note that if the evacuees show a maximum trust (leading to a fast communication), they tend to quickly find the exit and hence the collective action tends to prevent the occurrence of disasters.
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| 9. |
- Craig, W, et al.
(author)
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A new model for large amplitude long internal waves
- 2004
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In: Comptes Rendus. Mecanique. - : Elsevier BV. - 1873-7234 .- 1631-0721. ; 332:7, s. 525-530
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Journal article (peer-reviewed)abstract
- We derive a new model for the description of large amplitude internal waves in a two-fluid system. The displacement of the interface between the two fluids is assumed to be of small slope, but no smallness assumption is made on the wave amplitude. The derivation of the model is based on the perturbation theory for Hamiltonian systems. In the case of a single fluid layer, the model reduces to the classical shallow water regime for surface water waves. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.
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| 10. |
- Ireman, Peter, et al.
(author)
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Using the gradients of temperature and internal parameters in Continuum Thermodynamics
- 2004
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In: Comptes rendus. Mecanique. - : Elsevier BV. - 1631-0721 .- 1873-7234. ; 332:4, s. 249-255
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Journal article (peer-reviewed)abstract
- In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius-Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004). © 2004 Académie des sciences. Published by Elsevier SAS. All rights reserved.
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