Projet de thèse en Physique de la Matière Condensée et du Rayonnement
Sous la direction de Mathieu Gibert.
Thèses en préparation à Grenoble Alpes , dans le cadre de Physique , en partenariat avec Institut Néel (laboratoire) et de Matière Condensée, Matériaux et Fonctions (equipe de recherche) depuis le 01-01-2017 .
Turbulence is a phenomenon encountered in many natural and industrial conditions: for energy production (turbulent mixing in engines, electricity production through wind energy), meteorological and environmental aspects, in transportation, in fusion, etc Many advances have been made in this field, both theoretically (after the pioneering work by Kolmogorov in the last century [1,2]), or in the engineering modeling through Computational Fluid Dynamics (CFD) so far however of limited predictive possibilities, due to the necessary crude assumptions they rely on. More recent approaches, that we intend to develop further, have started to revisit turbulence with all the tools of statistical physics of out of equilibrium systems [3,4,5,6]. During this PhD project, we will develop and study liquid helium turbulent flows. The very small kinematic viscosity of this atypical fluid makes it the perfect candidate to reach very high turbulence intensity in well-controlled laboratory experiments. Moreover, when cooled down below 2.17K (at saturation vapor pressure) [7] a very atypical phase called superfluid HeII appears. This state of matter is at the frontier between fluid and quantum mechanics. To describe it one needs to introduce the two fluids model [8] in which HeII is modeled as the superposition of a normal and a superfluid that interact through mutual friction between the normal fluid and the quantum vortices that are carrying the vorticity of the superfluid. These quantum vortices, introduced by R. Feynman [9] are analogous to a certain extent to the one found in superconductors. Vortices being the elementary brick that constitute a turbulent flow, quantum turbulence is expected to exhibit fundamentally different velocity statistics that we intend to uncover thanks to an advanced stochastic analysis that encompasses the common multifractal approaches. This project, mostly experimental, will take advantage of a newly developed cryostat called the Cryogenic Lagrangian Exploration Module (CryoLEM) at the Néel Institute. This cryostat is equipped with multiple angle optical access in order to perform 3D Lagrangian Particle Tracking (3D-LPT) on micron-sized particles evolving in turbulent helium-4 fluid or superfluid flow. Moreover, this experiment is entirely setup on a spinning table (up to 2 revolution per second) to study the influence of rotation on the different turbulent flows generated and control their anisotropy. The PhD will therefore have to acquire the knowledge on how to operate the CryoLEM, and to develop this experiment. Additionally to the Lagrangian 3D-LPT data, 1D Eulerian velocity measurements will be done using micro-fabricated hot wire developed by Dr. Girard at CEA-SBT. Context: This PhD will be hired as part of a collaborative project between Oldenburg University, CEA-SBT and Néel Institute. As an active member of this collaboration, the PhD student will also spend some time in Oldenburg, where he will acquire the necessary skills to analyze the data acquired in the CryoLEM with Pr. Peinke and collaborators. Also, he will participate in the SHREK (Superfluide à Haut Reynolds en Ecoulement de von Karman) measurement runs (approximately one month a year) being operated at CEA-SBT. [1] A.N. Kolmogorov, Dokl. Akad. Nauk. SSSR, 30, 299-303 (1941) et Dokl. Akad. Nauk. SSSR, 31, 538-541 (1941) [2] A. N. Kolmogorov, Journal of Fluid Dynamics, 13, 82-85 (1962) [3] R. Friedrich, J. Peinke, M. Sahimi and M. Reza Rahimi Tabar. Approaching Complexity by Stochastic Processes: From Biological Systems to Turbulence, Phys. Report, 506, 87-162 (2011) [4] R. Stresing and J. Peinke. Towards a stochastic multi-point description of turbulence New Journal of Physics 12, 103046 (2010). [5] D. Nickelsen, A. Engel: Probing small-scale intermittency with a fluctuation theorem; Phys. Rev. Lett. (2012) [6] R. Friedrich and J. Peinke. Description of a Turbulent Cascade by a Fokker-Planck Equation Phys. Rev. Lett. 78, 863 (1997) [7] R. J. Donnelly. Experimental Superfluidity. The University of Chicago Press, Chicago, 1967. [8] L. Landau. Theory of the Superfluidity of Helium II. Phys. Rev., 60 :356358, 1941. [9] R. P. Feynman. Applications of quantum mechanics to liquid helium. In C. J. Gorter, editor, Progress in Low Temperature Phys. volume 1, pages 1753, Amsterdam, 1955. North-Holland.
Lagrangian multipoint statistics of cryogenic turbulence based on stochastic processes reconstructed from experimental data.
Turbulence is a phenomenon encountered in many natural and industrial conditions: for energy production (turbulent mixing in engines, electricity production through wind energy), meteorological and environmental aspects, in transportation, in fusion, etc Many advances have been made in this field, both theoretically (after the pioneering work by Kolmogorov in the last century [1,2]), or in the engineering modeling through Computational Fluid Dynamics (CFD) so far however of limited predictive possibilities, due to the necessary crude assumptions they rely on. More recent approaches, that we intend to develop further, have started to revisit turbulence with all the tools of statistical physics of out of equilibrium systems [3,4,5,6]. During this PhD project, we will develop and study liquid helium turbulent flows. The very small kinematic viscosity of this atypical fluid makes it the perfect candidate to reach very high turbulence intensity in well-controlled laboratory experiments. Moreover, when cooled down below 2.17K (at saturation vapor pressure) [7] a very atypical phase called superfluid HeII appears. This state of matter is at the frontier between fluid and quantum mechanics. To describe it one needs to introduce the two fluids model [8] in which HeII is modeled as the superposition of a normal and a superfluid that interact through mutual friction between the normal fluid and the quantum vortices that are carrying the vorticity of the superfluid. These quantum vortices, introduced by R. Feynman [9] are analogous to a certain extent to the one found in superconductors. Vortices being the elementary brick that constitute a turbulent flow, quantum turbulence is expected to exhibit fundamentally different velocity statistics that we intend to uncover thanks to an advanced stochastic analysis that encompasses the common multifractal approaches. This project, mostly experimental, will take advantage of a newly developed cryostat called the Cryogenic Lagrangian Exploration Module (CryoLEM) at the Néel Institute. This cryostat is equipped with multiple angle optical access in order to perform 3D Lagrangian Particle Tracking (3D-LPT) on micron-sized particles evolving in turbulent helium-4 fluid or superfluid flow. Moreover, this experiment is entirely setup on a spinning table (up to 2 revolution per second) to study the influence of rotation on the different turbulent flows generated and control their anisotropy. The PhD will therefore have to acquire the knowledge on how to operate the CryoLEM, and to develop this experiment. Additionally to the Lagrangian 3D-LPT data, 1D Eulerian velocity measurements will be done using micro-fabricated hot wire developed by Dr. Girard at CEA-SBT. Context: This PhD will be hired as part of a collaborative project between Oldenburg University, CEA-SBT and Néel Institute. As an active member of this collaboration, the PhD student will also spend some time in Oldenburg, where he will acquire the necessary skills to analyze the data acquired in the CryoLEM with Pr. Peinke and collaborators. Also, he will participate in the SHREK (Superfluide à Haut Reynolds en Ecoulement de von Karman) measurement runs (approximately one month a year) being operated at CEA-SBT. [1] A.N. Kolmogorov, Dokl. Akad. Nauk. SSSR, 30, 299-303 (1941) et Dokl. Akad. Nauk. SSSR, 31, 538-541 (1941) [2] A. N. Kolmogorov, Journal of Fluid Dynamics, 13, 82-85 (1962) [3] R. Friedrich, J. Peinke, M. Sahimi and M. Reza Rahimi Tabar. Approaching Complexity by Stochastic Processes: From Biological Systems to Turbulence, Phys. Report, 506, 87-162 (2011) [4] R. Stresing and J. Peinke. Towards a stochastic multi-point description of turbulence New Journal of Physics 12, 103046 (2010). [5] D. Nickelsen, A. Engel: Probing small-scale intermittency with a fluctuation theorem; Phys. Rev. Lett. (2012) [6] R. Friedrich and J. Peinke. Description of a Turbulent Cascade by a Fokker-Planck Equation Phys. Rev. Lett. 78, 863 (1997) [7] R. J. Donnelly. Experimental Superfluidity. The University of Chicago Press, Chicago, 1967. [8] L. Landau. Theory of the Superfluidity of Helium II. Phys. Rev., 60 :356358, 1941. [9] R. P. Feynman. Applications of quantum mechanics to liquid helium. In C. J. Gorter, editor, Progress in Low Temperature Phys. volume 1, pages 1753, Amsterdam, 1955. North-Holland.