(6jq) Fundamental Modeling of Gas-Solid and Granular Flows

Research Interests

My research will use and develop fundamental models to better understand and predict gas-solid and granular multi-phase flows, which are pervasive in nature and industry.  Simulation tools are gaining traction in industry as companies aim to decrease R&D costs, but require further model validation and development for confidence in the accuracy of the predictions.  Fundamental modeling is necessary to develop tools that can be applied to a large range of disciplines, as particle flows often exhibit complex phenomena that cause empirical correlations to be unreliable as a general modeling tool.  My research can be applied to many fields, examples of which include: optimizing heat transfer to flowing particles for emerging energy technologies, predicting particle segregation and elutriation in fluidized bed reactors to improve safety and performance, and modeling the role that particle shape has on fluidization behavior for biomass particles.  

Successful Proposals

“MFIX DEM Enhancement for Industry-Relevant Flows”
            Role:                         co-author
            Collaborators:           Prof. Hrenya, Univ. Colorado (PI), Dr. Cocco, PSRI (co-PI),
                                             Dr. Grout, NREL (co-PI), and Dr. Hauser, Univ. Colorado (co-PI)
            Funding Agency:      U.S. Department of Energy, National Energy Technology Laboratory   
            Amount:                   $827,421
            Dates:                       Aug 2015 – Feb 2017

“Simulating Multiphase Heat Transfer in a Novel Receiver for Concentrating Solar Power (CSP) Plants”
            Role:                         co-PI
            Collaborators:           Prof. Hrenya, Univ. Colorado (PI), Dr. Pannala, ORNL (co-PI)
            Funding Agency:      U.S. Department of Energy, Office of Science
            Amount:                   5M Titan-core hours at OLCF ($166,667 equivalent)
            Dates:                       Jul 2015 – Jun 2016

“Heat Transfer in Granular Flows: Understanding Similarities and Differences with Molecular Fluids”
            Role:                         co-PI
            Collaborators:           Prof. Christine Hrenya, Univ. Colorado (PI)
            Funding Agency:      National Science Foundation – Thermal Transport Processes    
            Amount:                   $320,000
            Dates:                       May 2015 – Apr 2018

“Simulating Multiphase Heat Transfer in a Novel Receiver for Concentrating Solar Power (CSP) Plants”
            Role:                         co-PI
            Collaborators:           Prof. Hrenya, Univ. Colorado (PI), Dr. Pannala, ORNL (co-PI)
            Funding Agency:      Department of Energy Office of Science
            Amount:                   15M Titan-core hours at OLCF ($500,000 equivalent)
            Dates:                       Jul 2014 – Jun 2015

Research Experience

I have used many simulation methods to study fluid dynamics in a wide range of disciplines.  In my current postdoctoral work at the National Energy Technology Laboratory (July 2015 – present),  I use simulations to aid development of fluidized bed reactors that will process up to 900,000 gallons of sodium bearing nuclear waste.  The large volume of nuclear waste is reduced by dual fluidized-bed steam reformers to a smaller amount of waste material that can be safely stored.  The simulations are used to “look” inside each vessel to identify regions of attrition, channeling, or poor mixing that can adversely affect system performance.

From March 2013 – July 2015, I worked with Prof. Hrenya at The University of Colorado as a postdoctoral researcher.  My project studied how solid particles perform as a heat transfer fluid for use in concentrating solar power.  I performed discrete element simulations to test the validity of previous continuum heat transfer models and found that the previous models failed to yield accurate predictions.  After identifying the shortcomings of previous models, I then developed a new fundamental continuum heat transfer model that was valid over a wide range of solar receiver configurations.

My PhD and MS training was done in the aerospace engineering department at The University of Texas at Austin, under the guidance of Professors David Goldstein and Philip Varghese.  I studied how the rocket exhaust plume from a lunar lander interacts with the surface, eroding and entraining lunar regolith into a dangerous high velocity spray, where particle speeds can exceed 1 km/s.  The direct simulation Monte Carlo method was used to simulate the rocket plume and the entrainment of dust for various landing scenarios.  The maximum particle speeds and trajectories were predicted for single- and multi-engine landers, which will help ensure the safety of future landers and potential lunar outposts.

Teaching Experience

During graduate school, I worked as a teaching assistant for two semesters, guiding undergraduates through a low-speed fluid dynamics laboratory.  I also guest-lectured for an undergraduate fluid dynamics course on multiple occasions.

During my postdoctoral appointment at The University of Colorado, I mentored two undergraduate workers through the undergraduate research program, one on a project to study hydrodynamic instabilities for falling particles, and another doing simulations.  I guided one student as he prepared a poster for the Rocky Mountain Advanced Computing Consortium, where he earned third place in the student poster competition.

Sample Publications

Morris, A., Pannala, S., Ma, Z., and Hrenya, C., (2015) “A conductive heat transfer model for particle flows over immersed surfaces,” International Journal of Heat and Mass Transfer, Vol. 89, pp 1277-1289.

Morris, A., Goldstein, D., Varghese, P., and Trafton, L., (2015) “Approach for modeling rocket plume impingement and dust dispersal on the Moon,” Journal of Spacecraft and Rockets, Vol. 52, pp 362-374.

Morris, A., Varghese, P., and Goldstein, D., (2011) “Monte Carlo solution of the Boltzmann equation via a discrete velocity model,” Journal of Computational Physics, Vol. 230, pp 1265-1280.