Macrotransport processes: Brownian tracers as stochastic averagers in effective medium theories of heterogeneous media
- Massachusetts Inst. of Tech., Cambridge (United States)
Macrotransport processes (generalized Taylor dispersion phenomena) constitute coarse-grained descriptions of comparable convective diffusive-reactive microtransport processes, the latter supposed governed by microscale linear constitutive equations and boundary conditions, but characterized by spatially nonuniform phenomenological coefficients. Following a brief review of existing applications of the theory, the author focuses - by way of background information-upon the original (and now classical) Taylor - Aris dispersion problem, involving the combined convective and molecular diffusive transport of a point-size Brownian solute molecule (tracer) suspended in a Poiseuille solvent flow within a circular tube. A series of elementary generalizations of this prototype problem to chromatographic-like solute transport processes in tubes is used to illustrate some novel statistical-physical features. These examples emphasize the fact that a solute molecule may, on average, move axially down the tube at a different mean velocity (either larger or smaller) than that of a solvent molecule. Moreover, this solute molecule may suffer axial dispersion about its mean velocity at a rate greatly exceeding that attributable to its axial molecular diffusion alone. Such chromatographic anomalies represent novel macroscale non-linearities originating from physicochemical interactions between spatially inhomogeneous convective-diffusive-reactive microtransport processes.
- OSTI ID:
- 5436415
- Report Number(s):
- CONF-9006380-; CODEN: JSTPB
- Journal Information:
- Journal of Statistical Physics; (United States), Vol. 62:5-6; Conference: Workshop on dynamics of concentrated systems, Los Alamos, NM (United States), 13-15 Jun 1990; ISSN 0022-4715
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
POROUS MATERIALS
MASS TRANSFER
AEROSOLS
BOUNDARY CONDITIONS
BROWNIAN MOVEMENT
CHROMATOGRAPHY
CONVECTION
DEPOSITION
DIFFUSION
FLUID MECHANICS
HETEROGENEOUS EFFECTS
LAMINAR FLOW
PACKED BEDS
RESEARCH PROGRAMS
SOLUTES
STATISTICAL MECHANICS
SUSPENSIONS
COLLOIDS
DISPERSIONS
ENERGY TRANSFER
FLUID FLOW
HEAT TRANSFER
MATERIALS
MECHANICS
SEPARATION PROCESSES
SOLS
665000* - Physics of Condensed Matter- (1992-)