INVESTIGADORES
IPPOLITO Irene Paula
artículos
Título:
Time dependence and local structure of tracer dispersion in oscillating liquid Hele-Shaw flows
Autor/es:
YANINA L. ROHT; HAROLD AURADOU; JEAN PIERRE HULIN; DOMINIQUE SALIN; RICARDO CHERTCOFF; IRENE IPPOLITO
Revista:
PHYSICS OF FLUIDS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: American Institute of Physics; Año: 2015 vol. 27
ISSN:
1070-6631
Resumen:
Passive tracer dispersion in oscillating Poiseuille liquid flows of zero net velocityis studied experimentally in a Hele-Shaw cell and numerically by 2D simulations:this study is particularly focused on the time dependence and local properties ofthe dispersion. The dispersion mechanism is found to be controlled by the ratioτm/T of the molecular diffusion time across the gap and the oscillation period (whenmolecular diffusion parallel to the flow is negligible). The 2D numerical simulationscomplement the experiments by providing the local concentration c(x, z, t) at a givendistance z from the cell walls (instead of only the average over z). Above a timelapse scaling like τm, the variation of c with the distance x along the flow becomesa Gaussian of width constant with z while the mean distance ¯ x may depend bothon z and t. For τm/T . 2, the front spreads through Taylor-like dispersion and thenormalized dispersivity scales as τm/T. The front oscillates parallel to the flowwith an amplitude constant across the gap; its width increases monotonically at arate modulated at twice the flow frequency, due to variations of the instantaneousdispersivity. For τm/T & 20, the molecular diffusion distance during a period of theflow is smaller than the gap and the normalized dispersivity scales as (τm/T)−1. Theoscillations of the different points of the front follow the local fluid velocity: thisproduces a reversible modulation of the global front width at twice the flow frequencyand in quadrature with that in the Taylor-like regime.