Fractal-generated turbulence and mixing: flow physics and some industrial implications

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New industrial flow solutions based on new flow concepts are urgentlyneeded to meet the unprecedented requirements set by the dramaticallyevolving energy, environmental and climatic constraints. What isneeded is not just improvements to existing solutions, but radical newdevelopments that can dramatically increase energy savings and reduceadverse environmental impacts. The development of new flow concepts onwhich such solutions will eventually be based requires unprecedentedfully resolved simulations and laboratory experiments because existingturbulence models cannot be applied indiscriminately on radically newflow concepts.One very recent example of a new flow concept originating from the UKis turbulent flows generated by fractal grids (figure 1). As attestedby recent patent applications by Imperial Innovations,proof-of-concept studies at Imperial and reports in various popularscience and engineering periodicals (Food Manufacture, June 2008; TheChemical Engineer, July 2008; Process Engineering, 18 July 2008;Speciality Chemicals, September 2008; Scientific Computing World,August 2008; see http://www3.imperial.ac.uk/tmfc/popular) this classof new flow concepts offers alternative solutions for industrialmixers, silent airbrakes and spoilers, natural ventilation, sun-roofsand combustion. In this proposal, we focus on new industrial staticinline mixers.These new flow concepts also pose unexpected challenges to turbulenceresearch and modelling. Over the past 60 years, efforts in turbulencehave been mostly in ad-hoc modelling of specific turbulent flows andthe progress has been limited. A fundamental understanding ofturbulence dynamics is needed if we want the development of an entireraft of new flow concepts to become a realistic possibility. For this,a well-designed and well-targeted experiment is required where theseturbulence dynamics can be set out of joint so as to give us clues forhow to understand and, if possible, control them. This is the otherfocus of this research proposal and it directly relates to the firstbecause both relate to the same new flow concept: turbulence generatedby fractal grids.