Improved algorithm for solving nonlinear parabolized stability equations

• Published in: Chinese physics B Vol. 25; no. 8; pp. 234 - 241
• Main Author: 赵磊 张存波 刘建新 罗纪生
• Format: Journal Article
• Language: English
• Published: 01.08.2016
• Subjects: Algorithms; Disturbances; Hypersonic boundary layer; Instability; Mathematical models; Nonlinearity; Parabolized stability equations; Stability; 一致性算法; 抛物化稳定性方程; 改进算法; 求解; 直接数值模拟; 超音速边界层; 迭代过程; 非线性效应
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/25/8/084701

Due to its high computational efficiency and ability to consider nonparallel and nonlinear effects, nonlinear parabolized stability equations（NPSE） approach has been widely used to study the stability and transition mechanisms. However,it often diverges in hypersonic boundary layers when the amplitude of disturbance reaches a certain level. In this study, an improved algorithm for solving NPSE is developed. In this algorithm, the mean flow distortion is included into the linear operator instead of into the nonlinear forcing terms in NPSE. An under-relaxation factor for computing the nonlinear terms is introduced during the iteration process to guarantee the robustness of the algorithm. Two case studies, the nonlinear development of stationary crossflow vortices and the fundamental resonance of the second mode disturbance in hypersonic boundary layers, are presented to validate the proposed algorithm for NPSE. Results from direct numerical simulation（DNS） are regarded as the baseline for comparison. Good agreement can be found between the proposed algorithm and DNS, which indicates the great potential of the proposed method on studying the crossflow and streamwise instability in hypersonic boundary layers.