THE PRIMARY GOAL OF THE PROPOSED WORK IS TO INTEGRATE THE DIFFERENT INSTABILITY MECHANISMS INTO A UNIFIED FRAMEWORK THAT CAN CONSISTENTLY EXPLAIN ALL THE PAST EXPERIMENTAL AND COMPUTATIONAL OBSERVATIONS. TOWARDS THIS END, THEY PLAN TO PURSUE A NOVEL MULTISCALE APPROACH, WHEREBY CARRYING OUT THE FOLLOWING FOUR TASKS, THEY WILL COMBINE THE POWERS OF THREE DIFFERENT COMPUTATIONAL/ANALYTICAL METHODOLOGIES. TASK-I IS PARTICLE-RESOLVED MICROSCALE SIMULATIONS OF LARGE CLUSTERS OF PARTICLES IN PLANAR, CYLINDRICAL, AND SPHERICAL CONFIGURATIONS SUBJECTED TO AN INTENSE SHOCK. THESE SIMULATIONS WILL BE CAREFULLY DESIGNED TO ALLOW FIRST-PRINCIPLE INVESTIGATION OF PROCESSES SUCH AS FORCE-CHAIN PROPAGATION, COMPRESSION/EXPANSION WAVE-INDUCED FRAGMENTATION OF PARTICLE CLUSTERS AND CHANNELING INSTABILITY IN THEIR ELEMENTARY FORM. TASK-II IS MULTIMODAL NONLINEAR INSTABILITY ANALYSIS OF THE CONFIGURATIONS INVESTIGATED IN TASK-I USING FILTERED MULTIPHASE FLOW EQUATIONS. THIS APPROACH WILL SERVE TWO IMPORTANT PURPOSES. FIRST, IT WILL ALLOW THE EARLY INSTABILITIES OBSERVED IN TASK-I TO BE RELATED TO THEIR LATE TIME GROWTH BY CLASSICAL RT AND RM INSTABILITIES. SECOND, IT WILL PERMIT PROPER SCALING OF THESE INSTABILITIES TO LARGER SYSTEMS AND THEREBY SERVE AS A BRIDGE BETWEEN TASK-I AND TASK-III. TASK-III WILL CONSIDER EULER-LAGRANGE DISCRETE ELEMENT METHODOLOGY MESOSCALE SIMULATIONS OF EXPLOSIVE DISPERSAL OF PARTICLES. THESE SIMULATIONS WILL BE LARGE-SCALE LONG-TIME EXTENSIONS OF THE CANONICAL CONFIGURATIONS CONSIDERED IN TASK-I. THEY WILL SERVE TO BOTH VERIFY THE EL-DEM SIMULATION APPROACH, AS WELL AS EXPLORE THE COMPLETE SPATIAL-TEMPORAL RANGE OF INSTABILITIES. THESE SIMULATIONS WILL REPLICATE CONDITIONS OF COMPANION EXPERIMENTAL CONFIGURATIONS AND WILL SERVE TO FIRMLY ESTABLISH THE UNDERLYING MECHANISMS OF INSTABILITY AND THEIR INTERPLAY IN GENERATING THE COMPLEX PARTICULATE STRUCTURES MEASURED IN THE EXPERIMENTS. TASK-IV WILL CONSIDER EULER-LAGRANGE MESOSCALE SIMULATIONS OF EXPLOSIVE DISPERSAL OF REACTIVE PARTICLES. THESE SIMULATIONS WILL CONSIDER CONFIGURATIONS THAT HAVE BEEN STUDIED IN PAST EXPERIMENTS, WHOSE DETAILED MEASUREMENTS CAN SERVE AS A BENCHMARK FOR VALIDATION. UNCERTAINTY QUANTIFICATION WILL BE A KEY COMPONENT OF INTEGRATION OF THIS TASK WITH THE OTHER TASKS.