Loading...
Search for:
kelvin–helmholtz
0.006 seconds
Numerical investigation of two-phase secondary Kelvin-Helmholtz instability
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 228, Issue 11 , October , 2014 , Pages 1913-1924 ; ISSN: 09544062 ; Shadloo, M. S ; Manzari, M. T ; Sharif University of Technology
Abstract
Instability of the interface between two immiscible fluids representing the so-called Kelvin-Helmholtz instability problem is studied using smoothed particle hydrodynamics method. Interfacial tension is included, and the fluids are assumed to be inviscid. The time evolution of interfaces is obtained for two low Richardson numbers Ri=0.01 and Ri=0.1 while Bond number varies between zero and infinity. This study focuses on the effect of Bond and Richardson numbers on secondary instability of a two-dimensional shear layer. A brief theoretical discussion is given concerning the linear early time regime followed by numerical investigation of the growth of secondary waves on the main billow....
Collective Dynamics of Interacting Particles in Fluid Flow
, Ph.D. Dissertation Sharif University of Technology ; Jalali, Mir Abbas (Supervisor)
Abstract
Each of us at some point in our life has been astonished by the observation of the collective motion of certain animals such as birds, fishes or insects. These coherent and synchronized structures are apparently produced without the active role of a leader in the grouping and it has been reported even for some microorganisms such as bacteria or red blood cells. In all the mentioned examples agents are surrounding with the moving fluid which can affect the collective behavior of the system. The collaborative flock of birds in windy conditions and the swimming of fishes in rivers or along oceanic currents are some examples. Moreover, micro-organisms produce different collective behavior in the...
Experimental study on the interfacial instability of particle-laden stratified shear flows
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 40, Issue 4 , April , 2018 ; 16785878 (ISSN) ; Firoozabadi, B ; Sharif University of Technology
Springer Verlag
2018
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 suspended particles. The interfacial instability of turbidity current is studied experimentally in the present research. Both Kelvin–Helmholtz and (asymmetric) Holmboe instabilities are observed during the experiments; the first one was downstream, and the second one was upstream of the obstacle. Kelvin–Helmholtz instability is observed by approximately zero (phase) speed with respect to the mean flow. With the aim of measuring spectral distribution of velocity fluctuations, the effects of some parameters are studied on interfacial waves;...
Linear spatial stability analysis of particle-laden stratified shear layers
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 6 , 2019 ; 16785878 (ISSN) ; Firoozabadi, B ; Sharif University of Technology
Springer Verlag
2019
Abstract
Hydrodynamic instabilities at the interface of stratified shear layers could occur in various modes. These instabilities have an important role in the mixing process. In this work, the linear stability analysis in spatial framework is used to study the stability characteristics of a particle-laden stratified two-layer flow. The effect of parameters such as velocity-to-density thickness ratio, bed slope, viscosity as well as particle size on the stability is considered. A simple iterative method applying the pseudospectral collocation method that employed Chebyshev polynomials is used to solve two coupled eigenvalue equations. Based on the results, the flow becomes stable for Richardson...
2D numerical simulation of density currents using the SPH projection method
, Article European Journal of Mechanics, B/Fluids ; Volume 38 , 2013 , Pages 38-46 ; 09977546 (ISSN) ; Firoozabadi, B ; Mahdinia, M ; Sharif University of Technology
2013
Abstract
Density currents (DCs) or gravity currents are driven by gravity in a fluid environment with density variation. Smoothed Particle Hydrodynamics (SPH) has been proved to have capabilities such as free surface modeling and accurate tracking of the immiscible-fluids interface that can be useful in the context of gravity currents. However, SPH applications to gravity currents have been limited to often-coarse simulations of high density-ratio currents. In this work, the SPH projection method is tried to solve currents with very low density-ratios (close to one), at a resolution, that captures the Kelvin-Helmholtz instabilities at the fluids interface. Existing implementations of the SPH...