The Experts below are selected from a list of 7362 Experts worldwide ranked by ideXlab platform
Moshe Schwartz - One of the best experts on this subject based on the ideXlab platform.
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Shape fluctuations of a Deformable Body in a randomly stirred host fluid.
Physical Review E, 2003Co-Authors: Gad Frenkel, Moshe SchwartzAbstract:We consider a Deformable Body immersed in an incompressible fluid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we investigate the deformations of the Body. The shape is decomposed into spherical harmonic modes. We study the correlations of these modes for a general class of random flows that include, as a special case, the flow due to thermal agitation. Our results are general, in the sense that they are applicable to a large class of Deformable bodies with energy that depends only on the shape of the Body, and a general class of random flows.
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Diffusion of a nearly spherical Deformable Body in a randomly stirred host fluid.
Physical Review E, 2002Co-Authors: Moshe Schwartz, Gad FrenkelAbstract:Consider a Deformable Body immersed in an incompressible liquid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we investigate the motion of the Body, calculate its mean squared displacement for a correlation function of general form and consider several usefull families of correlation functions. We also consider, in detail, the case of thermal agitation and the validity of the small deformation approximation.
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Diffusion of a Deformable Body in a random flow
Physica A-statistical Mechanics and Its Applications, 2001Co-Authors: Gad Frenkel, Moshe SchwartzAbstract:We consider a Deformable Body immersed in an incompressible liquid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we calculate the diffusion constant of the Body. We give explicitly the dependence of the diffusion constant on the velocity correlations in the liquid and on the size of the Body. We emphasize the particular case in which the random velocity field follows from thermal agitation.
Gad Frenkel - One of the best experts on this subject based on the ideXlab platform.
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Shape fluctuations of a Deformable Body in a randomly stirred host fluid.
Physical Review E, 2003Co-Authors: Gad Frenkel, Moshe SchwartzAbstract:We consider a Deformable Body immersed in an incompressible fluid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we investigate the deformations of the Body. The shape is decomposed into spherical harmonic modes. We study the correlations of these modes for a general class of random flows that include, as a special case, the flow due to thermal agitation. Our results are general, in the sense that they are applicable to a large class of Deformable bodies with energy that depends only on the shape of the Body, and a general class of random flows.
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Diffusion of a nearly spherical Deformable Body in a randomly stirred host fluid.
Physical Review E, 2002Co-Authors: Moshe Schwartz, Gad FrenkelAbstract:Consider a Deformable Body immersed in an incompressible liquid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we investigate the motion of the Body, calculate its mean squared displacement for a correlation function of general form and consider several usefull families of correlation functions. We also consider, in detail, the case of thermal agitation and the validity of the small deformation approximation.
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Diffusion of a Deformable Body in a random flow
Physica A-statistical Mechanics and Its Applications, 2001Co-Authors: Gad Frenkel, Moshe SchwartzAbstract:We consider a Deformable Body immersed in an incompressible liquid that is randomly stirred. Sticking to physical situations in which the Body departs only slightly from its spherical shape, we calculate the diffusion constant of the Body. We give explicitly the dependence of the diffusion constant on the velocity correlations in the liquid and on the size of the Body. We emphasize the particular case in which the random velocity field follows from thermal agitation.
A. R. Galper - One of the best experts on this subject based on the ideXlab platform.
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Hydrodynamics and stability of a Deformable Body moving in the proximity of interfaces
Physics of Fluids, 1999Co-Authors: A. R. Galper, Touvia MilohAbstract:The motion of a Deformable Body embedded in an inviscid irrotational nonuniform ambient flow field in the proximity of interfaces is treated here using a newly developed Hamiltonian formalism. The corresponding dynamic equations governing the motion of the Body are derived and their integrability is investigated. We find that the presence of boundaries results in an additional chaotization of a Body’s motion. Based on the derived Hamiltonian formalism the Liapunov stability of the motion of a Body translating parallel or towards a remote flat wall is also considered using the Energy-Casimir approach. The appropriate stability criteria are derived. Finally some applications for bubble dynamics concerning an influence of a periodical deformation of a bubble on its motion is presented.
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Motion stability of a Deformable Body in an ideal fluid with applications to the N spheres problem
Physics of Fluids, 1998Co-Authors: A. R. Galper, T. MilohAbstract:The Liapunov stability problem of the translation or spiraling motion of an arbitrary Deformable Body (the deformation of which is governed by the corresponding Hamiltonian) is treated here using the modified Energy–Casimir approach. The appropriate stability criteria are derived. It is shown that some unstable translational motions can be stabilized by a deformational or rotational motion. This formalism is further applied to the stability problem related to the motion of N (generally unequal) rigid spheres embedded in a potential flow field. The assembly of N-spheres is treated as an entire N-connected single Deformable Body. The Liapunov stability of the motion of two spheres in the direction orthogonal to their lines of centers and that of three spheres in the direction orthogonal to their plane of centers, is demonstrated and proven as a special case. Some existing conditions of clustering for a bubble cloud are also rederived and extended.
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Dynamic equations of motion for a rigid or Deformable Body in an arbitrary non-uniform potential flow field
Journal of Fluid Mechanics, 1995Co-Authors: A. R. Galper, Touvia MilohAbstract:In this paper we present a general method for calculating the hydrodynamic loads (forces and moments) acting on a Deformable Body moving with six degrees of freedom in a non-uniform ambient potential flow field. The corresponding expressions for the force and moment are given in a moving (Body-fixed) coordinate system. The newly derived system of nonlinear differential equations of motion is shown to possess an important antisymmetry property. As a consequence of this special property, it is demonstrated that the motion of a rigid Body embedded into a stationary flow field always renders a first integral. In a similar manner, we show that the motion of a Deformable Body in the presence of an arbitrary ambient flow field is Hamiltonian. A few practical applications of the proposed formulation for quadratic shapes and for weakly non-uniform external fields are presented. Also discussed is the self-propulsion mechanism of a Deformable Body moving in a non-uniform stationary flow field. It leads to a new parametric resonance phenomenon.
T. Miloh - One of the best experts on this subject based on the ideXlab platform.
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Motion stability of a Deformable Body in an ideal fluid with applications to the N spheres problem
Physics of Fluids, 1998Co-Authors: A. R. Galper, T. MilohAbstract:The Liapunov stability problem of the translation or spiraling motion of an arbitrary Deformable Body (the deformation of which is governed by the corresponding Hamiltonian) is treated here using the modified Energy–Casimir approach. The appropriate stability criteria are derived. It is shown that some unstable translational motions can be stabilized by a deformational or rotational motion. This formalism is further applied to the stability problem related to the motion of N (generally unequal) rigid spheres embedded in a potential flow field. The assembly of N-spheres is treated as an entire N-connected single Deformable Body. The Liapunov stability of the motion of two spheres in the direction orthogonal to their lines of centers and that of three spheres in the direction orthogonal to their plane of centers, is demonstrated and proven as a special case. Some existing conditions of clustering for a bubble cloud are also rederived and extended.
Nancy S. Pollard - One of the best experts on this subject based on the ideXlab platform.
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Fast simulation of skeleton-driven Deformable Body characters
ACM Transactions on Graphics, 2011Co-Authors: Junggon Kim, Nancy S. PollardAbstract:We propose a fast physically-based simulation system for skeleton-driven Deformable Body characters. Our system can generate realistic motions of self-propelled Deformable Body characters by considering the two-way interactions among the skeleton, the Deformable Body, and the environment in the dynamic simulation. It can also compute the passive jiggling behavior of a Deformable Body driven by a kinematic skeletal motion. We show that a well-coordinated combination of: (1) a reduced Deformable Body model with nonlinear finite elements, (2) a linear-time algorithm for skeleton dynamics, and (3) explicit integration can boost simulation speed to orders of magnitude faster than existing methods, while preserving modeling accuracy as much as possible. Parallel computation on the GPU has also been implemented to obtain an additional speedup for complicated characters. Detailed discussions of our engineering decisions for speed and accuracy of the simulation system are presented in the article. We tested our approach with a variety of skeleton-driven Deformable Body characters, and the tested characters were simulated in real time or near real time.