Gas-particle flows in fluidized beds and riser reactors are inherently unstable, and they manifest fluctuations over a wide range of length and time scales. Two-fluid models for such flows reveal unstable modes whose length scale is as small as ten particle diameters. Yet, because of limited computational resources, gas-particle flows in large fluidized beds are invariably simulated by solving discretized versions of the two-fluid model equations over a coarse spatial grid. Such coarse-grid simulations do not resolve the small-scale spatial structures which are known to affect the macroscale flow structures both qualitatively and quantitatively. Thus there is a need to develop filtered two-fluid models which are suitable for coarse-grid simulations and capturing the effect of the small-scale structures through closures in terms of the filtered variables. The overall objective of the project is to develop validated closures for filtered two-fluid models for gas-particle flows, with the transport gasifier as a primary, motivating example. In this project, highly resolved three-dimensional simulations of a kinetic theory based two-fluid model for gas-particle flows have been performed and the statistical information on structures in the 100-1000 particle diameters length scale has been extracted. Based on these results, closures for filtered two-fluid models have been …

The Petascale Computing Enabling Technologies (PCET) project addressed challenges arising from current trends in computer architecture that will lead to large-scale systems with many more nodes, each of which uses multicore chips. These factors will soon lead to systems that have over one million processors. Also, the use of multicore chips will lead to less memory and less memory bandwidth per core. We need fundamentally new algorithmic approaches to cope with these memory constraints and the huge number of processors. Further, correct, efficient code development is difficult even with the number of processors in current systems; more processors will only make it harder. The goal of PCET was to overcome these challenges by developing the computer science and mathematical underpinnings needed to realize the full potential of our future large-scale systems. Our research results will significantly increase the scientific output obtained from LLNL large-scale computing resources by improving application scientist productivity and system utilization. Our successes include scalable mathematical algorithms that adapt to these emerging architecture trends and through code correctness and performance methodologies that automate critical aspects of application development as well as the foundations for application-level fault tolerance techniques. PCET's scope encompassed several research thrusts in computer science …

Daily newspaper from Sweetwater, Texas that includes local, state, and national news along with advertising.

Photograph of the exterior of an old drug store building in Anderson, Texas. The road is visible in the foreground.

Photograph of the exterior of the Grimes County courthouse in Anderson, Texas. A road with a white arrow painted on it is visible in the foreground.

Photograph of a carriage drawn by two horses and driven by a man in a green coat, on a road in Anderson, Texas. Trees and a building are visible in the background.

Photograph of a horse-drawn carriage driving on a road around the Grimes County courthouse in Anderson, Texas.

Photograph of a carriage stopped in front of a wooden barn in Anderson, Texas. A sign for the Fanthorp Inn is visible to the right.

Photograph of a dirt road in Anderson, Texas. A sign and a truck are visible to the right, and a horse-drawn carriage is stopped outside a wooden barn to the left.

Photograph of a sign by a wooden building in Anderson, Texas. A red and yellow carriage is partially visible to the left.

Photograph of a man in a green coat driving a carriage pulled by two white horses down a road in Anderson, Texas. A house and a blue truck are visible to the right, and a car follows the carriage.

Photograph of a horse-drawn carriage on a road in Anderson, Texas. A blue truck is parked on the grass to the right, and there are two buildings in the background.

Photograph of a carriage drawn by two white horses driving down a road in Anderson, Texas. The driver, a man in a green coat, blows a trumpet.

Photograph of people exiting a carriage pulled by two white horses and driven by a man in a green coat, in Anderson, Texas. A wooden barn and fence are visible to the left, and there are trees in the background.

Photograph of a man wearing a poncho and a woman wearing a black dress standing in front of a two-story white house in Anderson, Texas. A Texas flag hangs from the second floor balcony, and another person stands on the porch in the background.

Photograph of a horse-drawn carriage merging onto a road in Anderson, Texas. Trucks and buildings are visible in the background.

Photograph of a horse-drawn carriage driving past the Grimes County courthouse in Anderson, Texas.

Photograph of a red, yellow, and black carriage pulled by two white horses, sitting in front of a wooden barn in Anderson, Texas. There is a wooden fence in the background, and trees in the foreground.

Photograph of three stacked wooden boxes between a window and a desk in a building in Anderson, Texas.

Photograph of two tables, several chairs, a pile of logs, and a bucket in a room in Anderson, Texas. There are red curtains on the windows, and a fire in the fireplace.

Photograph of two white horses pulling a carriage down a road in Anderson, Texas. Two more horses are visible behind a fence made of wood posts and barbed wire to the right, and there are buildings and cars in the background.

Photograph of a family, including two children, a man, and a woman, getting out of a carriage pulled by two white horses in front of a wooden barn in Anderson, Texas. A man in a green coat sits on the box seat, another man in a brown jacket stands by the horses, and trees are visible in the background.

Photograph of a horse-drawn carriage driving past the Grimes County courthouse in Anderson, Texas. Buildings and trees are visible in the background.

Photograph of a red, yellow, and black carriage pulled by two white horses on a road in Anderson, Texas. Cars and a wooden fence are visible to the left.