Dr. Anshu Anand Talk

Aug 10, 2011 - 16:00

Aug 10, 2011 - 17:00

Creativity Hall (Room 118 Dept of Chemical Eng.)

Seminars

Dr. Anshu Anand University of Colorado at Boulder

Summary: Particulates are tiny subdivisions of solid matter placed in a fluid. Particulate flows are prevalent across a diverse range of industrial and geophysical processes. Examples include pharmaceutical processes conveying lines for transporting minerals ores food and agricultural products fluidized bed reactors debris flows and sediment transport. Despite recent advances owing to computer simulations particulate flow processes remain poorly understood. Understanding the physics of particulate flows can lead to avoiding problems before they occur and increase the efficiency of transport processes significantly. In this talk I will discuss two specific applications of the particulate flow modeling (1) discharge and segregation of granular materials in hopper flows and (2) erosion and transport of lunar regolith (soil) due to impingement by rocket exhaust plume during landing of spacecrafts. The first application investigates hopper discharge phenomenon from a quasi-3D rectangular hopper using the Discrete Element Method (DEM - each individual constituent particle is modeled separately and hence called discrete). Hoppers are widely used in industries to store and transfer granular materials. Two industrially relevant quantities are explored: (1) Discharge rate and (2) extent of discharge segregation from the hopper. A pendular liquid bridge force model describes the cohesion between the particles and the Bond number (ratio of cohesive force and gravitational force on a particle) characterizes the strength of the cohesive bond. For both cohesive and cohesionless granular media the effects of particle properties and hopper geometry on discharge rate are studied through DEM and compared to previously published experimental correlations. A modified correlation for discharge rate is developed for cohesive materials from cohesionless materials. In addition a bi-disperse granular material flowing from a 3-D hopper is simulated using DEM for cohesive particles and the extent of discharge segregation is characterized over time. The second application of particulate simulations pertains to the entrainment of lunar regolith (soil) by the supersonic plume of a landing rocket. This entrainment is often problematic due to scouring and dust-impregnation of surrounding hardware reduction in visibility for the crew and spoofing of the landing sensors. Hence it is extremely important to predict the erosion dynamics of regolith to both assess and reduce the problem. In the present work the parameters affecting the erosion rate are investigated using DEM. The flow of exhaust rocket plume has been studied using CFD at NASA and the results have been incorporated into this work. The results indicate that DEM simulations are capable of reproducing trends in the erosion rate that are known through other investigations and in addition give valuable insight into the significance of inter-particle collisions on the erosion rate. The latter is particularly important as it appears to gives rise to the phenomenon like instability in the erosion process and particle sedimentation which cannot be explained without taking into account the inter particle collisions.Biography: Anshu Anand is currently working as a postdoctoral research associate at University of Colorado at Boulder with Prof. Christine Hrenya since October 2009. He attended the Indian Institute of Technology Bombay and earned a bachelor’s degree in Chemical Engineering in May 2005. Research experience gained during this time included internship at the Max Planck Institut fur Chemie Mainz Germany. The speaker then enrolled at University of Florida Gainesville to pursue graduate studies in Chemical Engineering. While here his industrial experience was expanded by an internship with Pfizer. He received his PhD from the University of Florida in the summer of 2009 working with Prof. Jennifer S Curtis. He has extensive experience in the field of Particulate flows in which he has been working for past 7 years.