Unsteady flow interactions between a pair of advected vortex tubes and a rigid sphere

Kim, I.; Elghobashi, S.; Sirignano, William A.

doi:10.1016/s0301-9322(96)00058-4

Cited by 16 publications

(6 citation statements)

References 9 publications

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“…There have been a large number of fully resolved simulations investigating laminar flow over fixed particles (see Mei et al 1991;Kim et al 1993Kim et al , 1995Kim et al , 1997Chang & Maxey 1994Magnaudet et al 1995;Ghidersa & Dušek 2000;Mittal 2000;Tomboulides & Orszag 2000;Bagchi & Balachandar 2002 a-c), particles undergoing prescribed motion (see Mei 1994), and freely moving particles (see Kim et al 1998;Bagchi & Balachandar 2002a, 2003b. However, there are few simulations of fully resolved turbulent flow over particles.…”

Section: Objectives and Approachmentioning

confidence: 99%

Fully resolved simulations of particle-turbulence interaction

2005

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The interaction between a fixed particle and decaying homogeneous isotropic turbulence is studied numerically using an overset grid that provides resolution of all scales of fluid motion. A description of the numerical technique and validation of the solution procedure are presented. An ensemble of 64 simulations with the particle in different regions of the flow is computed. The particle diameter in the simulations is approximately twice the size of the unladen Kolmogorov length scale, and the maximum value of the particle Reynolds numbers due to the turbulent fluctuations is close to 20. Ensemble averages of quantities from the numerical solutions are used to investigate the turbulence modification and the fluid forces on the particle. Volume-averaged profiles of the turbulent kinetic energy and dissipation rate from the overset grid simulations reveal that the displacement of fluid by the particle and the formation of the boundary layer at the particle surface lead to turbulence modification in a local region. Time histories of the force applied to the particle from each overset grid simulation are compared to those predicted by a particle equation of motion. The particle equation of motion is shown to underpredict the root mean square (RMS) force applied to the particle by the turbulence. RMS errors between the forces from the overset grid simulation and those predicted by the particle equation of motion are shown to be between 15% and 30% of the RMS force on the particle. The steady viscous drag force is shown to be the dominant term in the particle equation of motion while the history integral term is negligible.

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Section: Objectives and Approachmentioning

confidence: 99%

Fully resolved simulations of particle-turbulence interaction

2005

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“…7 There is a need for developing finite-dimensional models of such systems not only for a better theoretical understanding of locomotion problems in nature, such as fish swimming and bird flight, but also for applications to emerging engineering technologies, such as the development of small autonomous underwater and aerial vehicles with limited propulsive power. Another potential area for applications is particle-laden flows or granular flows, referring to fluid flows which contain many small-sized solid particles, where the effects of gravity may be neglected compared to the other forces on the particle; see, for example, Kim et al 8 Finitedimensional models will help provide a better understanding of the dynamics of these coupled nonlinear solid-fluid systems through the study of the equilibria, stability, bifurcations, and symmetries in the models. One way of obtaining finite-dimensional models is to treat the body as rigid and the fluid flow as inviscid with the vorticity concentrated at N points using the point vortex approximation.…”

Section: Introductionmentioning

confidence: 99%

Symmetric pairs of point vortices interacting with a neutrally buoyant two-dimensional circular cylinder

Shashikanth

2006

Physics of Fluids

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The dynamic interaction of N symmetric pairs of point vortices with a neutrally buoyant two-dimensional rigid circular cylinder in the inviscid Hamiltonian model of Shashikanth et al. ͓Phys. Fluids 14, 1214 ͑2002͔͒ and Shashikanth ͓Reg. Chaotic Dyn. 10, 1 ͑2005͔͒ is examined. The model may be thought of as a section of an inviscid axisymmetric model of a neutrally buoyant sphere interacting with N coaxial circular vortex rings and has possible applications to problems such as fish swimming. The Hamiltonian structure of this half-space model is first presented. The cases N = 1 and N = 2 are then examined in detail. Equilibria and bifurcations are studied, and for both these cases an important bifurcation parameter involving the total linear "momentum" of the system, the strength of the vortex pairs, and the radius of the cylinder emerges. For N = 1, it is shown that there exist the moving Föppl equilibrium and the moving normal line equilibrium ͑in which the vortices in the pair are located on the top and bottom of the moving cylinder͒. For N = 2, when ⌫ 1 = ⌫ 2 and when ⌫ 1 =−⌫ 2 , there exists another set of equilibrium configurations. Linear stability analysis of all these equilibria, within the symmetric class of solutions, is carried out and phase portraits presented. In addition, for N = 1, the velocity and acceleration surfaces for the cylinder are presented.

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“…They also studied the effects of vortex size and offset distance between the particle and the vortex tube on the temporal distributions of the forces acting on the particle. The same authors [7] extended their investigations to the interactions between a pair of advected vortex tubes and a rigid sphere and presented some new results. The idealized model of an isolated eddy is too simple to represent a real turbulent flow consisting of a range of vortical motion of arbitrary orientation, however, as Rockwell [1] pointed out, particles dispersed in a region of turbulent flow experience some common features with those interacting with isolated vortices.…”

Section: Introductionmentioning

confidence: 97%

Viscous Interaction Between a Vortex Tube and a Rotating Spherical Particle

Niazmand

Renksizbulut

2003

Part & Part Syst Charact

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The transient advection of a cylindrical vortex tube in a viscous incompressible flow field and its interaction with a rotating/spinning spherical particle has been investigated numerically at Reynolds numbers in the range of 20 Re 200 for angular velocities of 0 W 0.5. The effects of vortex parameters such as size, circulation strength and initial position relative to the particle, on the temporal behavior of the lift and drag forces are studied. Vortex-sphere interactions bring about major changes in the flow field particularly when coupled with particle rotation. It is observed that the forces acting on the particle are significantly influenced during the time that the vortex core is in the vicinity of the particle. The extent of these local changes are about AE 30% in the drag coefficient and about AE 200% in the lift coefficient as compared to flow over a rotating solid sphere with no vortex interaction. It is also found that a vortex with core radius between one and two particle diameters creates the strongest temporal variations in the lift and drag coefficients. Furthermore, maximum lift variations occur for the vortex-particle head on collision, while a vortex with an offset distance of about one diameter from the principal flow axis generates the maximum drag variations.

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Unsteady flow interactions between a pair of advected vortex tubes and a rigid sphere

Cited by 16 publications

References 9 publications

Fully resolved simulations of particle-turbulence interaction

Fully resolved simulations of particle-turbulence interaction

Symmetric pairs of point vortices interacting with a neutrally buoyant two-dimensional circular cylinder

Viscous Interaction Between a Vortex Tube and a Rotating Spherical Particle

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