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Literatura académica sobre el tema "Disques protoplanétaires – Modèles mathématiques"
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Tesis sobre el tema "Disques protoplanétaires – Modèles mathématiques"
Griveaud, Philippine. "Migration de planètes géantes dans des disques à faible viscosité". Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5050.
Texto completoA paradigm shift in protoplanetary disc (PPD) modelling has recently occurred, favoring magnetically-driven disc winds in the upper layers over turbulence-driven accretion onto the central star. In this model, the disc's midplane would maintain very low viscosity levels. This shift in paradigm could have significant implications for planetary system formation. Over the past 30 years, the literature on planet-disc interactions has mostly considered highly viscous discs. This thesis investigates how a low-viscosity midplane influences the migration of multiple giant planets.In the first part of this thesis, we examine the migration of pairs of giant planets. Our results show a profoundly different migration behaviour of Jupiter and Saturn compared to that in a high-viscosity disc.Previously locked in a 3:2 mean motion resonance (MMR) and migrating outwards, we find them locked in a 2:1 MMR and migrating inwards. The study covers a wide parameter space, including the mass of the outer planet, which validates the robustness of our result. For any pair featuring an inner planet of Jupiter's mass, the 2:1 MMR is never crossed, resulting most likely in inward migration.In the second part of this thesis, we expand upon our initial study by adding Uranus and Neptune in the system. The aim of this project was to explore what resonant chains of multiple giant planets can form in a low-viscosity disc, and whether these configurations can evolve into forming the Solar System in the post gas disc phase. First, we find that building stable resonant chains of giant planets in a low-viscosity disc is quite challenging. Lower viscosity results in wider and deeper gaps opened by the giant planets, which reduces the disc's damping effect. Consequently, when planets enter a resonance, the resonant angle stays closer to circulation, weakening the chain. Despite these challenges, our exploration of numerous configurations revealed five stable resonant chains of four or five planets for two different disc thicknesses.Additionally, we discovered that in a thin (and thus cold) PPD, the four giant planets reverse their migration direction and move outwards. We then investigated whether these resonant chains could serve as initial conditions for the Nice Model -- a giant planet instability phase occurring after the gas disc dispersal.Through a statistical study of N-Body simulations, we found that chains formed in cold PPDs yield about a 1% success rate in reproducing the current Solar System, whereas those formed in a thicker disc are highly stable and do not replicate the Nice Model. This success rate is assessed against four criteria designed to match features of today's Solar System. A 1% success aligns with the Nice Model literature, and is sufficient to explain our uncommon system. We conclude that the Solar System could have emerged from a low-viscosity disc, provided the disc was cold and the leftover planetesimal disc was massive.This work presents the first fully consistent dynamical study of the giant planets in the Solar System, covering their migration in the protoplanetary disc up to the Nice Model instability.Finally, the only system with multiple protoplanets observed in a protoplanetary disc to date, PDS 70, has two giant planets located near the 2:1 MMR. It is compelling to compare these findings with those from the first part of this thesis. However, observations of protoplanetary discs trace the dust component of the disc. Therefore, to effectively compare numerical simulations with observed systems, it is crucial to incorporate dust into the numerical models. In an effort to replicate the PDS 70 system, we have begun integrating dust into our simulations from our initial work. This project aims to assess whether a low-viscosity disc can accurately reproduce both the dynamical evolution of the two planets in PDS 70 and the observed dust structure in the system
Baruteau, Clément. "Vers des scénarios prédictifs de la migration planétaire". Phd thesis, Observatoire de Paris, 2008. http://tel.archives-ouvertes.fr/tel-00334456.
Texto completoBaruteau, Clément. "Vers des scénarios prédictifs de la migration planétaire". Phd thesis, Observatoire de Paris (1667-....), 2008. https://theses.hal.science/tel-00334456.
Texto completoThe recent detection of extrasolar planets has provided an exciting opportunity to test our theories of planet formation and evolution. An impressive result is the significant proportion of giant planets located much closer to their star than Mercury is from our own Sun! These planets should have formed further out in the protoplanetary disc, thus one needs to explain how they could move closer to their host star. Remarkably enough, such an explanation was proposed well before the discovery of the first exoplanet. It considered the interaction between a planet and the protoplanetary disc, which leads to a decrease of the planet's semi-major axis. This is known as planetary migration. Many studies have shown that the migration timescale of low-mass planets is much shorter than the lifetime of the disc. All planets should therefore have migrated to the vicinity of their host star! This is at least in contradiction with the locations of the planets in our Solar System. In order to elaborate predictive scenarios of planet formation and evolution, it is of primary interest to refine our understanding of disc-planet interactions. The inclusion of the disc self-gravity is an illustration of this. With analytical and numerical arguments, I show that discarding the self-gravity leads to a significant overestimate of the differential Lindblad torque for migrating low-mass planets. Another aspect explored in this thesis is the impact of the gas thermodynamics on migration. I show that the thermodynamic evolution of the disc induces an additional contribution to the corotation torque, which may dramatically slow down or even reverse the migration of low-mass planets
Cabral, Nahuel. "Modèles de synthèses de populations planétaires avec cavité magnétique et effets de marées stellaires". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY088.
Texto completoIn this thesis, we have been interested on the effects of the magnetic cavity and the stellar tides in synthetic planet population. The magnetic cavity is thought be important at the formation phase since it can truncates the gaseous disk and potentially stops the inward migration of planets (Lin et al. 1995). In this work we modified the standard radial viscous equation in order to take into account the effect of the magnetic torque on the gaseous disk (Armitage et al. 1999). Moreover, the stellar tides have been included in an analytical way as in (Bénitez-Llambay et al. 2011). For this work, we used the planetary model of Bern (Mordasini et al. 2012) at which we included both effects. The end of the thesis compare the synthetic orbital distribution with the orbital distribution observed by Kepler (Howard et al. 2012).Finally, a last chapter treats a topic different than the rest of the thesis. We tested the so called pebble mechanism (Ormel&Klahr2010) in the planetary formation model of Bern. So far, this chapter is a first step to a more complete model. However, we show that the numerical implementation is working well
Aoun, Nabli Mohamed Seghaïer. "Simulation numérique de l'hydrodynamique et du mélange axial dans les colonnes d'extraction pulsées à garnissage disques-couronnes". Toulouse, INPT, 1995. http://www.theses.fr/1995INPT002G.
Texto completoGardan, Erwan. "Etude des disques externes de galaxies spirales : observation et modélisation de Messier 33". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13474.
Texto completoKirouani, Taki-Eddine. "Etude expérimentale et modélisation de l’hydrodynamique et du transfert de l’oxygène dans un bioréacteur à disques rotatifs". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10128.
Texto completoThis work aims to quantify and to model the oxygen transfer in bubbles-less production with an objective of intensification of bioprocess performances and selectivity. Lab- and numeric works are achieved in model system air-water, in a rotating biological contactor suitable for bio-pesticides productions. The oxygen transfer coefficient is determined using dynamic method at conditions, similar to those used in bio-production of bio-pesticides by fermentation. To predict the oxygen mass transfer coefficient (KLa) empirical models based on dimensional analysis are proposed. The model based on the volume of the liquid film formed on the on the rotating discs, seems more appropriate since, at various studied experimental conditions, the obtained results are close to experimental ones. Limits of empirical mass transfer models are discussed and new areas of investigation are proposed, namely the numeric modeling. A convective-diffusion model has been suggested. The model takes into account the variation of the film thickness on the disc surface and the level of immersion of the disc in the volume of liquid phase. The model provide the degree of the film saturation, as well as the concentration evolution during one rotation of the disk for a different depths of the film and for different rotation velocities. The same model is modified to describe the oxygen transfer in the case when the disc immersion is less than 50%. The model predictions are in agreement with results from the literature
Derrouiche, Amil. "Osmo-inelastic response of intervertebral disc : experiments and constitutive modeling". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I068/document.
Texto completoBack pain is considered the first source of chronic pain in developed countries. Although the exact origin of the pain remains uncertain, there is often a correlation with the interve1tebral dise. Understanding the response of this soft tissue is necessary to improve treatments and prevent pain. The objective of this thesis is to provide a better understanding of the different couplings between thebiochemical environment, the microstructure and the biomechanical behavior. Experimental observations are reported at the level of the vertebra-disc-vertebra unit and at the level of the annulus fibrosu s. A new chemo-mechanical model is mathematical formulated and incorporated into a computer code in order to better understand the couplings and to reproduce the mechanics of the unit. An extension to chemo-mechano-biological coupling makes it possible to envisage a better understanding of the degeneration mechanisms
Ehtash, Moamer. "Purification des eaux polluées par du phénol dans un pertracteur à disques tournants". Phd thesis, INSA de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00635855.
Texto completoColmant, Maxime. "Multi-dimensional analysis of software power consumptions in multi-core architectures". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10094/document.
Texto completoEnergy-efficient computing is becoming increasingly important. Among the reasons, one can mention the massive consumption of large data centers that consume as much as 180,000 homes. This trend, combined with environmental concerns, makes energy efficiency a prime technological and societal challenge. Currently, widely used power distribution units (PDUs) are often shared amongst nodes to deliver aggregated power consumption reports, in the range of hours and minutes. However, in order to improve the energy efficiency of software systems, we need to support process-level power estimation in real-time, which goes beyond the capacity of a PDUs. In particular, the CPU is considered by the research community as the major power consumer within a node and draws attention while trying to model the system power consumption. Over the last few years, a dozen of ad hoc power models have been proposed to cope with the wide diversity and the growing complexity of modern CPU architectures. In this thesis, we rather propose PowerAPI for learning power models and building software-defined power meters that provide accurate power estimation on modern architectures. With the emergence of cloud computing, we propose BitWatts and WattsKit for leveraging software power estimation in VMs and clusters. A finer level of estimation may be required to further evaluate the effectiveness of the software optimizations and we therefore propose codEnergy for helping developers to understand how the energy is really consumed by a software. We deeply assessed all above approaches, thus demonstrating the usefulness of PowerAPI to better understand the software power consumption on modern architectures