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Moving Particles (moving + particle)
Selected AbstractsA two-grid fictitious domain method for direct simulation of flows involving non-interacting particles of a very small sizeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2010A. Dechaume Abstract The full resolution of flows involving particles whose scale is hundreds or thousands of times smaller than the size of the flow domain is a challenging problem. A naive approach would require a tremendous number of degrees of freedom in order to bridge the gap between the two spatial scales involved. The approach used in the present study employs two grids whose grid size fits the two different scales involved, one of them (the micro-scale grid) being embedded into the other (the macro-scale grid). Then resolving first the larger scale on the macro-scale grid, we transfer the so obtained data to the boundary of the micro-scale grid and solve the smaller size problem. Since the particle is moving throughout the macro-scale domain, the micro-scale grid is fixed at the centroid of the moving particle and therefore moves with it. In this study we combine such an approach with a fictitious domain formulation of the problem resulting in a very efficient algorithm that is also easy to implement in an existing CFD code. We validate the method against existing experimental data for a sedimenting sphere, as well as analytical results for motion of an inertia-less ellipsoid in a shear flow. Finally, we apply the method to the flow of a high aspect ratio ellipsoid in a model of a human lung airway bifurcation. Copyright © 2009 John Wiley & Sons, Ltd. [source] Using particles for 3D texture sculptingCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 4 2001ich Bene Abstract Particle systems have been used in computer graphics for many different purposes, including visual simulation of fur, grass, hair, and similar fuzzy textures and shapes. The underlying theories used in these algorithms are usually quite complex and are mostly based on simulation of diffuse-limited aggregation, cellular development, reaction-diffusion models, etc. This leads to high time complexity of these algorithms. The purpose of this paper is to show that collision detection and distance keeping among moving particles can generate similar realistic textures efficiently. This approach is easy to implement, sufficiently fast allowing for interactive modeling, and inherits the major features from the previously published techniques. We first construct a scene consisting of generators of particles, attractors, and cutters. The generators generate oriented particles, and the attractors attract or repulse them. When collision with the cutter is detected, the particle performs an action according to its state and position in the 3D space. Every particle has assigned a table of possible actions that is used for solving these critical states. Trajectories of the particles are then used as a resulting shape of the texture. Copyright © 2001 John Wiley & Sons, Ltd. [source] Particulate flow simulations using lubrication theory solution enrichmentINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2003G. J. Wagner Abstract A technique for the numerical simulation of suspensions of particles in fluid based on the extended finite element method (X-FEM) is developed. In this method, the particle surfaces need not conform to the finite element boundaries, so that moving particles can be simulated without remeshing. The finite element basis is enriched with the Stokes flow solution for flow past a single particle and the lubrication theory solution for flow between particles. The latter enrichment allows the simulation of particles that come arbitrarily close together without refining the mesh in the gap between them. Example problems illustrating both types of enrichment are shown, along with a study of a 50% solution in channel flow. Copyright © 2003 John Wiley & Sons, Ltd. [source] The extended finite element method for rigid particles in Stokes flowINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2001G. J. Wagner Abstract A new method for the simulation of particulate flows, based on the extended finite element method (X-FEM), is described. In this method, the particle surfaces need not conform to the finite element boundaries, so that moving particles can be simulated without remeshing. The near field form of the fluid flow about each particle is built into the finite element basis using a partition of unity enrichment, allowing the simple enforcement of boundary conditions and improved accuracy over other methods on a coarse mesh. We present a weak form of the equations of motion useful for the simulation of freely moving particles, and solve example problems for particles with prescribed and unknown velocities. Copyright © 2001 John Wiley & Sons, Ltd. [source] A framework for teaching scientific inquiry in upper secondary school chemistryJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 7 2010Lisette van Rens Abstract A framework for teaching scientific inquiry in upper secondary chemistry education was constructed in a design research consisting of two research cycles. First, in a pilot study a hypothetical framework was enriched in collaboration with five chemistry teachers. Second, a main study in this community of teachers and researchers was conducted on the process of designing teaching scientific inquiry based on the enriched framework. Also, the enactment by five teachers and 80 students (age 17) of a designed inquiry module on "Diffusion: moving particles" was studied. This resulted in a theoretically and practically founded framework for teaching scientific inquiry, in which an iterative cycle of inquiry for students and a student inquiry community are essential. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47:788,806, 2010 [source] | ||||||||||