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interfacial-instability
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Experimental and Theoretical Study on Interfacial Instabilities of Turbidity Currents
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Co-Advisor)
Abstract
Turbidity currents are one of the more frequently observed types of stratified flows. In these currents, the density difference is created as a result of particles. Hydrodynamic instabilities at the interface of these currents could occur in various modes and have an important role in the mixing process. The main goal of this study is to investigate the interfacial stability of turbidity current, theoretical and experimentally. The linear stability analysis in temporal and spatial framework are used for studying the stability characteristics of a particle-laden stratified two-layer flow for two different background density profiles: smooth (hyperbolic tangent) and piecewise linear. The...
Experimental and theoretical investigation of cubic stabilization of instability of an interface in surface wave motion
, Article Physics of Fluids ; Volume 32, Issue 2 , 26 February , 2020 ; Behzadi, S ; Safaie, A ; Fazeli, M ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Motivated by recent laboratory and field observations, this paper reports the first quantitative measurements of the stabilization phase of interfacial instability in a two-layer fluid in surface wave motion. The instability results from the formation of a resonant triad between the surface wave and noise-level sub-harmonic interfacial waves. To exclude the effects of interfacial mixing on the interaction, the experiments were carried out with immiscible fluids. Carrying out a resonant interaction analysis to the third order of nonlinearity using a Lagrangian formulation, we also show for the first time that the three-wave resonance is inherently accompanied by a harmonic four-wave resonant...
Interfacial instabilities in sediment suspension flows
, Article Journal of Fluid Mechanics ; Vol. 758, issue , November , 2014 , p. 312-326 ; Jalali, M. A ; Maleki, M ; Sharif University of Technology
Abstract
We report the existence of interfacial instability in the two-dimensional channel flow of a sediment suspension whose particles diffuse in the carrier fluid due to shear-induced collisions. We derive partial differential equations that govern the deformations of the interface between the sediment suspension and the clear fluid, and devise a perturbation method that preserves the positivity of the particle volume fraction. We solve perturbed momentum, particle transport and deforming interface equations to show that a Kelvin-Helmholtz-type unstable wave develops at the interface for wavelengths longer than a critical value. Short-wavelength oscillations of the interface are damped due to...
Interfacial instability of growing drop: experimental study and conceptual analysis
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 347, Issue 1-3 , 2009 , Pages 167-174 ; 09277757 (ISSN) ; Bastani, D ; Kragel, J ; Miller, R ; Sharif University of Technology
Elsevier
2009
Abstract
Capillary pressure experiments were performed at the water/hexane interface including adsorption and mass exchange of hexanol under different conditions. The results from growing drop experiments show that instabilities due to Marangoni convection not only depend on the same parameters as have been reported for quasi-static interfaces, such as direction of mass transfer, distribution coefficient and ratio of diffusion coefficients, but also on the experimental conditions such as dispersed phase flow rate, capillary tip size, size of growing drop and its lifetime. Based on a new flow expansion model for mass transfer, a new approach is presented for data analysis, which includes the various...