SBIR-STTR Award

The ever increasing need to process large quantities of solidfuels like coal provides strong motivation to study the dynamicsof flowing granular materials. Laboratory experiments arehampered by the lack of adequate diagnostic tools and means tocontrol the flows. Field experiments are very expensive as well.Also, scale dependence implies that results of laboratory orsemi-industrial scale experiments may not be relevant to largescale industrial systems. Recent algorithmic advances as well asthe availability of fast superworkstations enable the use of newmolecular dynamic simulations to study granular systemscontaining up to a million particles in practically any desiredgeometry and for any prescribed geometrical or dynamicalproperties of the particles or the boundaries. The measurement offrillll velocity, stress, granular temperature, concentrationfields, flow rates, density profiles, and other macroscopic andmicroscopic properties of the flows using simulation results isnow possible. The large number of particles that can now besimulated enables the study of relatively large scale systems. Incontrast, most previous particle dynamics computer codes couldsimulate a few thousand particles in a simple enclosure and a fewhundred particles in complex flow situations. The existence of anew clustering scale in granular systems which indicates that thedynamical properties of small systems may be qualitativelydifferent from those encountered in large systems has now beendemonstrated. This renders simulations of systems containing arelatively small number of particles of limited applicability.The diagnostic simulation code to be developed in Phase I will befast, user friendly and sufficiently versatile to handle variablegeometries and particle and boundary properties.Anticipated Results /Potential Commercial Applications as described by the awardee: The coal and fossil industry, powerplants, and other industries worldwide can benefit significantlyfrom reliable diagnostic and design methods. The design andoperation of silos, bins, chutes, hoppers, and of many othersystems will be improved, rendering them more efficient.Troubleshooting in such systems can be highly facilitated by theuse of good diagnostic tools. Compliance with the Clean Air ActAmendments of 1990 will be easier while keeping energy prices atreasonable levels. State-of-the-art algorithmic methods andstatistical mechanical techniques will be harnessed to achievethe goal of producing a user-friendly simulation tool andassociated diagnostics for solid fuel flows.

There has been a rapid increase in both the quantity and diversity of the granular materials that are used in industry, creating an urgent need for a design and diagnostic tool for granular flows. The energy, metallurgical, food/agricultural, pharmaceutical, and chemical industries are but a few of the industries that use and/or require the handling of bulk solids. These industries all suffer large losses as a result of poor performance of bulk solids handling devices which are subject to frequent clogging, unsteady and erratic flows, undesirable separation, flooding, and even structural failure. Recent algorithmic advances as well as the availability of fast superworkstations enable the use of Molecular Dynamic (MD) simulations to study granular systems of up to the order of 1,000,000 particles in practically any desired geometry and for any prescribed geometrical or dynamical properties of the particles or boundaries. In Phase I, highly efficient simulators for rapidly sheared granular systems in two and in three dimensions were constructed and the dynamics of about one million particles were computed on superworkstations, demonstrating the technical feasibility of a MD simulation based diagnostic and design tool. In addition, a prototype user-friendly Graphical User Interface (GUI) was developed, ensuring the ease of use of this code. This GUI is based on advanced programming tools to provide portability across a variety of user platforms. Both user-friendliness and portability are deemed essential to the commercial success of the Phase II product. In Phase II the development of an advanced diagnostic and design tool for flowing granular materials and of the GUI will be completed. Numerous enhancements will be made to the code to extend the range of its industrial applicability, allowing arbitrary particle-particle and particle-wall interactions, and providing standard and advanced diagnostics. The development of a hybrid MD and continuum simulator will enable further extensions of the size of systems to be simulated. The resulting MD diagnostic and design tool should prove a significant contribution to the field of bulk solids handling.Anticipated Results/Potential Commercial Applications as described by the awardee:This MD simulation code offers a relatively inexpensive, nonintrusive, and almost model independent means of design and troubleshooting in granular flow systems. Its versatility and ease of use (particularly through the GUI) will make it much faster (and cheaper) than standard methods of diagnosis or experimentally based design. As such, the MD code should quickly become a valuable tool in the design and operations of silos, chutes, pneumatic conveyors, drums, and fluidized beds in the energy and other industries. Realistic market estimates suggest about 100 user sites leading to a substantial commercial market.