(3ew) Discrete Particle Modeling of Dense Multiphase Flows

     
Dense dispersed flow has been identified as a complex
system, which consists of a large number of finite
solid particles, gaseous bubbles or liquid droplets that are convected by a laminar or turbulent flow of a continuous fluid.
Of significance are the ongoing research efforts to develop numerical
models and to understand the flow behavior of such complex
system. Several models at different resolution
scale levels have been formulated, among which the
discrete particle model (DPM) shows a great potential to unearth the system
complexity for its merit of modeling the dispersed phase in a natural way.

      During my PhD study I developed a 2D hard-sphere
discrete particle/bubble model and coupled it to computational fluid dynamics. Later
I solved several difficulties in 3D code development, including the accurate void
fraction calculation under unstructured grid and the implicit two-phase
coupling algorithm. I also proposed an efficient particle collision handling
algorithm which allows a full 3D simulation of gas-particle systems having
several millions of particles without parallel computing. The developed 3D DPM
code has been integrated into the commercial CFD software FLUENT by
user-defined functions. The code has been validated through a comprehensive
comparison to the experiments and can capture many important characteristics of
gas-solid fluidization systems, such as bubbling, spouting, particle clustering
and core-annulus flow structures under specific operating conditions.

     
I have a great interest in developing numerical models and have gained a
lot experiences in scientific computation, especially in high performance
computing since I worked as a research assistant on the project of meso-scale air pollution modeling at the Hong Kong
Polytechnic University. My research goal is to develop an efficient, versatile
and robust 3D-DPM code that can be used to study the dispersed multiphase
systems. This relies not only on programming skills but also on a thorough
understanding of the physics inside, such as all kinds of interactions taking
place in a dispersed system. The latter actually helps a lot on designing
numerical algorithms. My future research mainly focuses on the following topics

1)  3D-DPM code development for simulation of bubbly
flow with free surface

2) 
Three-phase flow and particle-scale heat transfer in fluidized bed by
DPM simulations

3)  Particle mixing and segregation in granular
flows

      In this poster session, I will present my
recent work on the 3D parallel DPM code development under TeraGrid
and LONI HPC environment. By designing a specific interface, the developed parallel
code can run separately for granular flow simulation or corporate with the CFD
solver for dispersed gas-solid flow simulation based on the user's demand. Both
MPI and multithreading techniques are adopted in the code development. The
parallel code is scalable up to 128 CPUs.

Post-doctoral advisor

K. Nandakumar,
Gordon A. and Mary Cain endowed chair professor, Cain Department of Chemical
Engineering, Louisiana State University, Baton Rouge,
LA 70803

Selected publications

[1] Wu C.L., Berrouk A. S., Nandakumar K.,
Three-dimensional discrete particle model for gas-solid fluidized beds on
unstructured mesh. Chemical Engineering Journal 152: 514-529, 2009

[2] Wu C. L.,
Zhan J.M., Li Y.S., Lam K.S., Berrouk A.S., Accurate
void fraction calculation for three-dimensional discrete particle model for
gas-solid fluidized bed on unstructured mesh, Chemical Engineering Science 64:1260-1266,
2009.

[3] Wu C. L., Berrouk A. S., Nandakumar K., An
efficient chained-hash-table strategy for collision handling in hard-sphere
discrete particle modeling, Powder Technology 197: 58-67, 2010

[4] Wu C. L.,
Yang Y., Wong S.L., Alvin Lai C. K., A new mathematical model for irradiance
field prediction of Upper-Room Ultraviolet Germicidal Systems, Journal of
Hazardous Materials 189: 173-185, 2011

[5] Wu C.L.,
Zhan J.M., Li Y.S., Lam K.S., Dense
particulate flow model on unstructured mesh, Chemical Engineering Science 61:5726-5741,
2006