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SUMMARY:Hierarchical parcel-swapping (HiPS) representation of turbulent fl
 ow &amp\; mixing - Alan Kerstein\, Sandia National Labs (Retired)
DTSTART:20150918T130000Z
DTEND:20150918T140000Z
UID:TALK60801@talks.cam.ac.uk
CONTACT:Simone Hochgreb
DESCRIPTION:An economical representation of effects of turbulence on the t
 ime-evolving structure of diffusive scalar fields is obtained by introduci
 ng a hierarchical (tree) network connecting fluid parcels\, with effects o
 f turbulent advection represented by swapping pairs of sub-trees at rates 
 determined by turbulence time scales associated with the sub-trees. The fl
 uid parcels reside at the base of the tree. The tree structure partitions 
 the fluid parcels into adjacent pairs (or more generally\, p-tuples). Adja
 cent parcels intermix at rates governed by diffusion time scales based on 
 molecular diffusivities and parcel sizes. This simple procedure efficientl
 y accomplishes long-standing objectives of turbulent mixing model developm
 ent\, such as generating physically based time histories of fluid-parcel n
 earest-neighbor encounters and the associated spatial structure of turbule
 nt scalar fields. A strategy for implementing the method as a mixing sub-m
 odel like those commonly used in turbulent combustion simulations is outli
 ned. The formulation involves a parameter controlling the tree structure t
 hat can be used to set the effective spatial dimensionality\, which need n
 ot be an integer and can be arbitrarily small\, subject to practical limit
 ations. With the introduction of velocity components as well as scalars\, 
 this hierarchical parcel-swapping (HiPS) f­ormulation becomes a self-cont
 ained flow simulation\, as illustrated by its application to fully develop
 ed channel flow.
LOCATION:LR3A Engineering Department
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