TITLE:

COMPUTATIONAL MODELING AND BIFURCATION ANALYSIS OF BUBBLING FLUIDIZED PROCESSES

DATE:

Friday, April 25th, 2008

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Bing Zhu, PhD Candidate, Computational Science Research Center, San Diego State University

ABSTRACT:

Fluidization processes have many important applications in industry, in particular, in chemical, fossil, and petrochemical industries where good gas-solid mixing is required. Such mixing is commonly achieved through bubbles which are formed spontaneously and whose time-evolution appears to be governed by low-dimensional deterministic dynamics. Understanding the space and time dynamics in more detail is critical to future development of technologies that rely on the fluidization phenomenon—transport of solid particles by fluids—such as chemical reactors.

In response to this need, we use a low-dimensional, computational agent-based bubble model to study the changes in the global bubble dynamics in response to changes in the frequency of the rising bubbles. A computationally-based bifurcation analysis shows that the collective bubble dynamics undergoes a series of transitions from equilibrium points to highly periodic orbits, chaotic attractors, and even intermittent behavior between periodic orbits and chaotic sets. Using ideas and methods from nonlinear dynamics and time-series analysis, we are able to approximate nonlinear models that allow for long-term predictions and the possibility of developing control algorithms. Additionally, we employ the Proper Orthogonal Decomposition to better understand the bubble dynamics generated by multiple injectors.

-This is a joint project with the Chaos Group at Oak Ridge National Laboratory-

HOST:

Antonio Palacios and Peter Blomgren

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