an:06595609
Zbl 1338.35361
Fullmer, William D.; Lopez de Bertodano, Martin A.; Chen, Min; Clausse, Alejandro
Analysis of stability, verification and chaos with the Kreiss-Ystr??m equations
EN
Appl. Math. Comput. 248, 28-46 (2014).
00356357
2014
j
35Q35 35B25 35K40 35R25 37N15 76Txx
ill-posed; verification; chaos; two-fluid model
Summary: A system of two coupled PDEs originally proposed and studied by \textit{H. O Kreiss} and \textit{J. Ystr??m} [Math. Comput. Modelling 35, No. 11--12, 1271--1295 (2002; Zbl 1066.76064)], which is dynamically similar to a one-dimensional two-fluid model of two-phase flow, is investigated here. It is demonstrated that in the limit of vanishing viscosity (i.e., neglecting second-order and higher derivatives), the system possesses complex eigenvalues and is therefore ill-posed. The regularized problem (i.e., including viscous second-order derivatives) retains the long-wavelength linear instability but with a cut-off wavelength, below which the system is linearly stable and dissipative. A second-order accurate numerical scheme, which is verified using the method of manufactured solutions, is used to simulate the system. For short to intermediate periods of time, numerical solutions compare favorably to those published previously by the original authors. However, the solutions at a later time are considerably different and have the properties of chaos. To quantify the chaos, the largest Lyapunov exponent is calculated and found to be approximately 0.38. Additionally, the correlation dimension of the attractor is assessed, resulting in a fractal dimension of 2.8 with an embedded dimension of approximately 6. Subsequently, the route to chaos is qualitatively explored with investigations of asymptotic stability, traveling-wave limit cycles and intermittency. Finally, the numerical solution, which is grid-dependent in space-time for long times, is demonstrated to be convergent using the time-averaged amplitude spectra.
Zbl 1066.76064