propagation, and current rheological models are unable to generate the periodically
alternating bubbles that are observed experimentally. Coupling CFD simulations for
the gas phase with discrete element model (DEM) simulations for the particle phase
can properly account for interparticle interactions, including friction, which
reproduces the alternating bubble patterns in excellent quantitative agreement with
experiments. A detailed study of the gas and solid motion, using numerical simulations and experiments (bubble image analysis and particle image velocimetry),
offers fundamental insights into the pattern formation mechanism, with alternating
zones where solid or fluid mechanics dominate. The bubble patterns are also a
fingerprint for numerical simulation methods of fluidised beds, relevant beyond
pulsed fluidised beds.
Mapping the conditions under which regular bubble patterns with certain
characteristics form (namely bubble size and pattern wavelength), jointly with
controlled gas–solid mixing zones around the bubbles, allows an engineer to apply
this captivating phenomenon to gas–solid process intensification. The fundamental
insights provided by this thesis thus pave the road toward applications that build on
the formation of dynamically structured flows with controlled properties and gas–
solid contact, uniform in time and in space.
February 2021
Prof. Marc-Olivier Coppens
Ramsay Memorial Professor in Chemical Engineering
Centre for Nature-Inspired Engineering (CNIE)
University College London (UCL)
London, UK
x
Supervisor’s Foreword
alternating bubbles that are observed experimentally. Coupling CFD simulations for
the gas phase with discrete element model (DEM) simulations for the particle phase
can properly account for interparticle interactions, including friction, which
reproduces the alternating bubble patterns in excellent quantitative agreement with
experiments. A detailed study of the gas and solid motion, using numerical simulations and experiments (bubble image analysis and particle image velocimetry),
offers fundamental insights into the pattern formation mechanism, with alternating
zones where solid or fluid mechanics dominate. The bubble patterns are also a
fingerprint for numerical simulation methods of fluidised beds, relevant beyond
pulsed fluidised beds.
Mapping the conditions under which regular bubble patterns with certain
characteristics form (namely bubble size and pattern wavelength), jointly with
controlled gas–solid mixing zones around the bubbles, allows an engineer to apply
this captivating phenomenon to gas–solid process intensification. The fundamental
insights provided by this thesis thus pave the road toward applications that build on
the formation of dynamically structured flows with controlled properties and gas–
solid contact, uniform in time and in space.
February 2021
Prof. Marc-Olivier Coppens
Ramsay Memorial Professor in Chemical Engineering
Centre for Nature-Inspired Engineering (CNIE)
University College London (UCL)
London, UK
x
Supervisor’s Foreword