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4/28 12:00~14:00
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High-order discontinuous Galerkin scheme for the coagulation/fragmentation equation
Maxime Lombart (NTNU)
Particles coagulation and fragmentation are ubiquitous (raindrop formation, air pollution, combustion, polymerisation, astrophysics) and mathematically described by the Smoluchowski coagulation and the fragmentation equations. Solving these equations accurately while preserving tractable computational costs is a tremendous numerical challenge, yet critical for understanding the formation of the planets. In particular, low-order schemes do strongly overestimate the formation of large particles. We present a novel high-order discontinuous Galerkin algorithm (Lombart and Laibe 2021) that addresses all these issues. The algorithm is designed in a modular way to be coupled in other codes. In particular, we aim to perform the first 3D simulations of dusty protoplanetary discs that include realistic coagulation/fragmentation.
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Dynamics and formation of the Hydrogen Plume in the Vicinity of the Saturn’s Ring
Hua-Shan Shi (NCU)
The phenomenon, which is called "Ring Rain", is a transport process of the nano-dust entering Saturn's atmosphere from Saturn's rings by the gravitational effect (Mitchell et al., 2018; Perry et al., 2018). During the Cassini Proximal mission, a flux of about 1E+5 kg/s of nano-sized dust grains from the D-ring falling into the Saturnian atmosphere was detected by the Cassini CDA, INMS, and MIMI. The analysis from the observation of INMS also provides the detection of H2, He, CH4, H2O and NH3 in the upper atmosphere of Saturn (Serigano et al., 2020). On the other hand, the collisional interaction of the dust grains with Saturn's atmosphere would allow the generation of a population of escaping hydrogen molecules. It might be correlated with Saturn's narrow hydrogen gas plume which was observed by the UVIS experiment of Cassini. (Shemansky et al., 2009; Mitchell et al., 2008). In this work, we investigate the 3D orbital motion of different sizes of dust grains generated by the D-68 ringlet from a series of Monte Carlo collision simulations, and further simulate the spiraling motion of the accelerated gas particles.
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