Abstract
Instantaneous pressure measurements in air-water vertical upward flow in a circular pipe were analyzed to determine if the signals are consistent with deterministic chaotic behavior. Analysis of conventional Fourier power spectra characteristics yielded evidence consistent with a chaotic signal. Chaos measures were employed to provide both qualitative and quantitative evidence of the nature of the dynamics in bubbly flow (hemispherical cap), slug flow, and churn flow. A qualitative study of the system trajectory in phase space revealed dynamics consistent with a nonlinear system. The positive definite values of Kolmogorov entropy for all pressure signals quantitatively indicated that the system may be governed by chaotic dynamics. Therefore, the flow regimes studied in this investigation indicate the presence of a strange attractor.
