Time variability of viscosity parameter in differentially rotating discs |
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| Institution: | 1. Second Affiliated Hospital and School of Public Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China;2. Academy for Data Science and Global Health, Kathmandu, Nepal;3. National Centre for Youth Substance Use Research, Faculty of Health and Behavioral Sciences, The University of Queensland, Brisbane, Australia;4. School of Psychology, Faculty of Health and Behavioral Sciences, The University of Queensland, Brisbane, Australia;5. Department of Health Metrics Science, School of Medicine, University of Washington, Seattle, USA;6. ARC Centre of Excellence in Population Ageing Research (CEPAR), University of New South Wales, Sydney, Australia;7. School of Risk & Actuarial Studies, University of New South Wales, Sydney, Australia;8. School of Public Health, Faculty of Medicine, The University of Queensland, Brisbane, Australia |
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| Abstract: | We propose a mechanism to produce fluctuations in the viscosity parameter (α) in differentially rotating discs. We carried out a nonlinear analysis of a general accretion flow, where any perturbation on the background α was treated as a passive/slave variable in the sense of dynamical system theory. We demonstrate a complete physical picture of growth, saturation and final degradation of the perturbation as a result of the nonlinear nature of coupled system of equations. The strong dependence of this fluctuation on the radial location in the accretion disc and the base angular momentum distribution is demonstrated. The growth of fluctuations is shown to have a time scale comparable to the radial drift time and hence the physical significance is discussed. The fluctuation is found to be a power law in time in the growing phase and we briefly discuss its statistical significance. |
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| Keywords: | Accretion Accretion discs Hydrodynamics X-rays: binaries |
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