TRACER TIME DISTRIBUTION OF PARTICLES IN POROUS MEDIA

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 1075-1079
Author(s):  
MARIELA ARAUJO
Keyword(s):  
Porous Medium ◽  
Transit Time ◽  
Power Law ◽  
Time Distribution ◽  
Tracer Particle ◽  
Power Law Distribution ◽  
Low Velocity ◽  
Constant Flow Rate ◽  
Variable Permeability ◽  
Tracer Particles

We study the transit time distributions of tracer particles in a porous medium through which a constant flow rate is established. Our model assumes that non-Gaussian dispersion is due to the presence of low velocity zones or channels in parallel with a faster flow path. Each channel is represented as a trap and simulates the existence of variable permeability blocks inside the porous medium. The time the tracer particle spends inside each channel is related to the heterogeneity of the sample, and is assumed here to have a power-law distribution. We compare the transit time distribution of these particles for the case in which the traps are Poisson distributed with the one in which the trap distribution is a power-law function.

Empirical Analysis on Human Dynamics of QQ Group Communication

2014 ◽  
Vol 998-999 ◽  
pp. 1146-1150
Author(s):  
Rui Tian ◽  
Xu Han ◽  
Wen Jun Wang
Keyword(s):  
Power Law ◽  
Time Distribution ◽  
Group Communication ◽  
Communication Tool ◽  
Power Law Distribution ◽  
Human Dynamics ◽  
Event Time ◽  
Human Interactions ◽  
Power Law Exponent ◽  
Individual Human

The understanding of the temporal patterns of individual human interactions is essential in explaining many characteristics of human behavior. The instant communication tool QQ is developing rapidly on the network in recent years. Based on the QQ group communication records provided by some volunteers, this paper investigates the statistics of the inter-event intervals between two consecutive messages. The result shows that they follow power-law distribution. And there are obvious positive correlation between the activity of QQ group and the power-law exponent of inter-event time distribution. In further study, we find that the distribution displays a strong bursty property yet weak memory effects, then we analysis the distribution of the number of events in a bursty period.

Gradient and Percolative Clogging in Depth Filtration

1998 ◽  
Vol 09 (08) ◽  
pp. 1535-1543 ◽  
Author(s):  
Somalee Datta ◽  
Sidney Redner
Keyword(s):  
Porous Medium ◽  
Power Law ◽  
Filter Design ◽  
Pore Space ◽  
Power Law Distribution ◽  
Percolation Process ◽  
Trapped Particles ◽  
Downstream Distance ◽  
Depth Filtration ◽  
Flow Through

The phenomenon of clogging in depth filtration is investigated, in which a dirty fluid is "cleaned" by the trapping of dirt particles within the pore space during flow through a porous medium. This gives rise to a self-generated gradient percolation process which exhibits a power law distribution for the density of trapped particles at downstream distance x from the input, both in idealized and lattice networks. Implications for efficient filter design are also mentioned.

Free Convective Heat and Mass Transfer in a Doubly Stratified Porous Medium Saturated with a Power-Law Fluid

2009 ◽  
Vol 36 (6) ◽  
pp. 524-537 ◽  
Author(s):  
P. A. Lakshmi Narayana ◽  
P. V. S. N. Murthy ◽  
P. V. S. S. S. R. Krishna ◽  
Adrian Postelnicu
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Power Law ◽  
Power Law Fluid
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