scholarly journals Coarse-grid selection for parallel algebraic multigrid

1998 ◽  
pp. 104-115 ◽  
Author(s):  
Andrew J. Cleary ◽  
Robert D. Falgout ◽  
Van Emden Henson ◽  
Jim E. Jones
Keyword(s):  
Coarse Grid ◽  
Algebraic Multigrid ◽  
Selection For ◽  
Grid Selection

scholarly journals A Greedy Strategy for Coarse-Grid Selection

2007 ◽  
Vol 29 (5) ◽  
pp. 1825-1853 ◽  
Author(s):  
S. MacLachlan ◽  
Yousef Saad
Keyword(s):  
Coarse Grid ◽  
Greedy Strategy ◽  
Grid Selection

On the Convergence of System-AMG in Reservoir Simulation

SPE Journal ◽  
2018 ◽  
Vol 23 (02) ◽  
pp. 589-597 ◽  
Author(s):  
Sebastian Gries
Keyword(s):  
Linear Systems ◽  
Reservoir Simulation ◽  
Extreme Case ◽  
Coarse Grid ◽  
Algebraic Multigrid ◽  
Volume Balance ◽  
Coarse Grid Correction ◽  
Speed Up ◽  
Level Problem ◽  
Flexible Framework

Summary System-algebraic multigrid (AMG) provides a flexible framework for linear systems in simulation applications that involve various types of physical unknowns. Reservoir-simulation applications, with their driving elliptic pressure unknown, are principally well-suited to exploit System-AMG as a robust and efficient solver method. However, the coarse grid correction must be physically meaningful to speed up the overall convergence. It has been common practice in constrained-pressure-residual (CPR) -type applications to use an approximate pressure/saturation decoupling to fulfill this requirement. Unfortunately, this can have significant effects on the AMG applicability and, thus, is not performed by the dynamic row-sum (DRS) method. This work shows that the pressure/saturation decoupling is not necessary for ensuring an efficient interplay between the coarse grid correction process and the fine-level problem, demonstrating that a comparable influence of the pressure on the different involved partial-differential equations (PDEs) is much more crucial. As an extreme case with respect to the outlined requirement, linear systems from compositional simulations under the volume-balance formulation will be discussed. In these systems, the pressure typically is associated with a volume balance rather than a diffusion process. It will be shown how System-AMG can still be used in such cases.

Investigation of optimum anti-scatter grid selection for digital radiography: physical imaging properties and detectability of low-contrast signals

2012 ◽  
Vol 6 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Nobukazu Tanaka ◽  
Kentaro Naka ◽  
Aya Saito ◽  
Junji Morishita ◽  
Fukai Toyofuku ◽  
...  
Keyword(s):  
Digital Radiography ◽  
Low Contrast ◽  
Selection For ◽  
Grid Selection ◽  
Imaging Properties

Grid selection for oral cholecystography.

Radiology ◽  
1981 ◽  
Vol 139 (1) ◽  
pp. 234-235
Author(s):  
R E Miller ◽  
M J Besozzi
Keyword(s):  
Oral Cholecystography ◽  
Selection For ◽  
Grid Selection

Coarse grid classification: a parallel coarsening scheme for algebraic multigrid methods

2006 ◽  
Vol 13 (2-3) ◽  
pp. 193-214 ◽  
Author(s):  
Michael Griebel ◽  
Bram Metsch ◽  
Daniel Oeltz ◽  
Marc Alexander Schweitzer
Keyword(s):  
Multigrid Methods ◽  
Coarse Grid ◽  
Algebraic Multigrid ◽  
Algebraic Multigrid Methods

Parallel coarse-grid selection

2007 ◽  
Vol 14 (8) ◽  
pp. 611-643 ◽  
Author(s):  
David M. Alber ◽  
Luke N. Olson
Keyword(s):  
Coarse Grid ◽  
Grid Selection

scholarly journals Reaction of juvenile flounder to grid separators

2004 ◽  
Vol 61 (7) ◽  
pp. 1174-1178 ◽  
Author(s):  
Yoshiki Matsushita ◽  
Kaoru Fujita ◽  
Naoya Ikegami ◽  
Satoshi Ohata
Keyword(s):  
Paralichthys Olivaceus ◽  
Japanese Flounder ◽  
Tokyo Bay ◽  
Considerable Proportion ◽  
Beam Trawl ◽  
Light Conditions ◽  
Trawl Fishery ◽  
Selection For ◽  
Dark Conditions ◽  
Grid Selection

Abstract The reaction behaviour of juvenile Japanese flounder (Paralichthys olivaceus) to towed grids (0.5 × 0.2 m, horizontally, or vertically orientated bars at 10-mm intervals) was observed as a means of understanding fish behaviour in relation to grid selection for a beam trawl fishery in Tokyo Bay. Reaction behaviours were categorized within four patterns by grid types and illumination levels: (i) forward swimming in towed direction; (ii) swimming over the grid; (iii) sticking on the grid; and (iv) passing through the grid. The most dominant reaction pattern was forward swimming, but its ratio was higher for light than for dark conditions. Passing through the grid bars occurred most frequently with horizontal bars. Approximately 40% of tested fish passed through the grid in light conditions, approximately 30% in dark conditions. Most of these fish penetrated bar gaps head first, while a considerable proportion categorized as “forward swimming” kept swimming even though their tails or bodies had partly passed between the bars. It is concluded that penetration of flounders through bar gaps is governed by voluntary actions.

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