A Novel Hyperbolization Procedure for The Two-Phase Six-Equation Flow Model

Samet Y. Kadioglu ; Robert Nourgaliev ; Nam Dinh

关键词: EIGENVALUES;    FLOW MODELS;    FLUID FLOW;    INSTABILITY;    REACTORS;    RESOLUTION;    STABILITY;    TUNING;    TWO-PHASE FLOW Flow Model;    Hyperbolization;   

DOI  :  10.2172/1033898
RP-ID  :  INL/EXT-11-23551
PID  :  OSTI ID: 1033898
Others  :  TRN: US1200674

美国|英语

来源: SciTech Connect

【 摘 要 】

We introduce a novel approach for the hyperbolization of the well-known two-phase six equation flow model. The six-equation model has been frequently used in many two-phase flow applications such as bubbly fluid flows in nuclear reactors. One major drawback of this model is that it can be arbitrarily non-hyperbolic resulting in difficulties such as numerical instability issues. Non-hyperbolic behavior can be associated with complex eigenvalues that correspond to characteristic matrix of the system. Complex eigenvalues are often due to certain flow parameter choices such as the definition of inter-facial pressure terms. In our method, we prevent the characteristic matrix receiving complex eigenvalues by fine tuning the inter-facial pressure terms with an iterative procedure. In this way, the characteristic matrix possesses all real eigenvalues meaning that the characteristic wave speeds are all real therefore the overall two-phase flowmodel becomes hyperbolic. The main advantage of this is that one can apply less diffusive highly accurate high resolution numerical schemes that often rely on explicit calculations of real eigenvalues. We note that existing non-hyperbolic models are discretized mainly based on low order highly dissipative numerical techniques in order to avoid stability issues.