A MOLECULAR DYNAMIC AIDED ADVANCED DIAGNOSTIC TOOL FOR GRANULAR FLOWS

THE EVER INCREASING NEED TO PROCESS LARGE QUANTITIES OF SOLID FUELS LIKE COAL PROVIDES STRONG MOTIVATION TO STUDY THE DYNAMICS OF FLOWING GRANULAR MATERIALS. LABORATORY EXPERIMENTS ARE HAMPERED BY THE LACK OF ADEQUATE DIAGNOSTIC TOOLS AND MEANS TO CONTROL THE FLOWS. FIELD EXPERIMENTS ARE VERY EXPENSIVE AS WELL. ALSO, SCALE DEPENDENCE IMPLIES THAT RESULTS OF LABORATORY OF SEMI-INDUSTRIAL SCALE EXPERIMENTS MAY NOT BE RELEVANT TO LARGE SCALE INDUSTRIAL SYSTEMS. RECENT ALGORITTHMIC ADVANCES AS WELL AS THE AVAILABILITY OF FAST SUPERWORKSTATIONS ENABLE THE USE OF NEW MOLECULAR DYNAMIC SIMULATIONS TO STUDY GRANULAR SYSTEMS CONTAINING UP TO A MILLION PARTICLES IN PRACTICALLY ANY DESIRED GEOMETRY AND FOR ANY PRESCRIBED GEOMETRICAL OR DYNAMICAL PROPERTIES OF THE PARTICLES OR THE BOUNDARIES. THE MEASUREMENT OF FULL VELOCITY, STRESS, GRANULAR TEMPERATURE, CONCENTRATION FIELDS, FLOW RATES, DENSITY PROFILES, AND OTHER MACROSCOPIC AND MICROSCOPIC PROPERTIES OF THE FLOWS USING SIMULATION RESULTS IS NOW POSSIBLE. THE LARGE NUMBER OF PARTICLES THAT CAN NOW BE SIMULATED ENABLES THE STUDY OF RELATIVELY LARGE SCALE SYSTEMS. IN CONTRAST, MOST PREVIOUS PARTICLE DYNAMICS COMPUTER CODES COULD SIMULATE A FEW THOUSAND PARTICLES IN A SIMPLE ENCLOSURE AND A FEW HUNDRED PARTICLES IN COMPLEX FLOW SITUATIONS. THE EXISTENCE OF A NEW CLUSTERING SCALE IN GRANULAR SYSTEMS WHICH INDICATES THAT THE DYNAMICAL PROPERTIES OF SMALL SYSTEMS MAY BE QUALITATIVELY DIFFERENT FROM THOSE ENCOUNTERED IN LARGE SYSTEMS HAS NOW BEEN DEMONSTRATED. THIS RENDERS SIMULATIONS OF SYSTEMS CONTAINING A RELATIVELY SMALL NUMBER OF PARTICLES OF LIMITED APPLICABILITY. THE DIAGNOSTIC SIMULATION CODE TO BE DEVELOPED IN PHASE I WILL BE FAST, USER FRIENDLY AND SUFFICIENTLY VERSATILE TO HANDLE VARIABLE GEOMETRIES AND PARTICLE AND BOUNDARY PROPERTIES.