Self-sustained amplification of disturbances in pipe Poiseuille flow |
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| Institution: | 1. Center of Excellence in Design and Optimization of Energy Systems (CEDOES), School of Mechanical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran, Iran;2. School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran;3. Faculty of Applied Science, Department of Mechanical Engineering, The University of British Columbia, Point Grey Campus, Vancouver, BC V6T 1Z4, Canada |
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| Abstract: | The nonlinear development of disturbances in pipe Poiseuille flow is studied with a low-dimensional model. The basic system from which the model is derived governs disturbances closely related to the radial velocity and radial vorticity disturbances. The analysis is restricted to the interaction of the two first harmonics of streamwise elongated disturbances since they are the most transiently amplified ones in linear theory. In the resulting dynamical system a nonlinear feedback from the normal vorticity disturbance (which is transiently amplified according to linear theory) to the radial velocity disturbance is present. Above a threshold of the initial amplitude, the feedback leads to a self-sustained amplification of the disturbances continuing for all times. |
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