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原文传递 Direct Numerical Simulation of Interfacial Flows: Implicit Sharp-Interface Method (I-SIM)

题名：	Direct Numerical Simulation of Interfacial Flows: Implicit Sharp-Interface Method (I-SIM)
作者：	Dana Knoll;Vincent Mousseau;HyeongKae Park;Theo Theofanous;Robert Nourgaliev;
关键词：	Multiphysics22 GENERAL STUDIES OF NUCLEAR REACTORS; ACCURACY; ALGORITHMS; CONVECTION; DIFFUSION; GEOMETRY; OSCILLATIONS; PERFORMANCE; RESOLUTION; SHEAR; SIMULATION; STABILITY; VELOCITY
摘要：	In recent work (Nourgaliev, Liou, Theofanous, JCP in press) we demonstrated that numerical simulations of interfacial flows in the presence of strong shear must be cast in dynamically sharp terms (sharp interface treatment or SIM), and that moreover they must meet stringent resolution requirements (i.e., resolving the critical layer). The present work is an outgrowth of that work aiming to overcome consequent limitations on the temporal treatment, which become still more severe in the presence of phase change. The key is to avoid operator splitting between interface motion, fluid convection, viscous/heat diffusion and reactions; instead treating all these non-linear operators fully-coupled within a Newton iteration scheme. To this end, the SIM鈥檚 cut-cell meshing is combined with the high-orderaccurate implicit Runge-Kutta and the 鈥渞ecovery鈥?Discontinuous Galerkin methods along with a Jacobian-free, Krylov subspace iteration algorithm and its physics-based preconditioning. In particular, the interfacial geometry (i.e., marker鈥檚 positions and volumes of cut cells) is a part of the Newton-Krylov solution vector, so that the interface dynamics and fluid motions are fully-(non-linearly)-coupled. We show that our method is: (a) robust (L-stable) and efficient, allowing to step over stability time steps at will while maintaining high-(up to the 5th)-order temporal accuracy; (b) fully conservative, even near multimaterial contacts, without any adverse consequences (pressure/velocity oscillations); and (c) highorder-accurate in spatial discretization (demonstrated here up to the 12th-order for smoothin-the-bulk-fluid flows), capturing interfacial jumps sharply, within one cell. Performance is illustrated with a variety of test problems, including low-Mach-number 鈥渕anufactured鈥?solutions, shock dynamics/tracking with slow dynamic time scales, and multi-fluid, highspeed shock-tube problems. We briefly discuss preconditioning, and we introduce two physics-based preconditioners 鈥?鈥淏lock-Diagonal鈥?and 鈥淚nternal energy-Pressure-Velocity Partially Decoupled鈥? demonstrating the ability to efficiently solve all-speed flows with strong effects from viscous dissipation and heat conduction.
报告类型：	科技报告