Towards Simple Implicit Preconditioning Riemann Solvers for the Simulation of the Low Mach number Flows

• Main Authors: Ming-Jung Yang, 楊銘榮
• Other Authors: 牛仰堯
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/96313237209310800704

碩士 === 淡江大學 === 航空太空工程學系碩士班 === 104 === Here, a scalar matrix-free implicit type preconditioning hybrid AUSMD(R) solver for multi-phase flows is developed. The numerical stability problem caused by the multi-scale speed of sound due to uncertain dissipation terms in the current schemes which can be resolved by rescaling the eigenvalues of the Euler type system equations to enhance computational convergence. This paper presents implicit pre-conditioning approaches which indicate similarly accurate results obtained with the fully implicit and Runge-Kutta explicit schemes. The current used homogeneous two-phase mixture model with the assumption of kinematics and thermodynamics equilibriums. The thermodynamics behaviors of liquid phase, vapor phase and their phase transitional process are described by a temperature dependent hybrid equation of state which includes a mass-fraction averaged formula of water-vapor saturation process. The current work shows that the scalar matrix free implicit schemes are capable of improving the computational efficiency over its explicit counterpart. Several benchmark tests are used for numerical validations.