15 research outputs found
Lift force on an asymmetrical obstacle immersed in a dilute granular flow
This paper investigates the lift force exerted on an elliptical obstacle
immersed in a granular flow through analytical calculations and computer
simulations. The results are shown as a function of the obstacle size,
orientation with respect to the flow direction (tilt angle), the restitution
coefficient and ellipse eccentricity. The theoretical argument, based on the
force exerted on the obstacle due to inelastic, frictionless collisions of a
very dilute flow, captures the qualitative features of the lift, but fails to
reproduce the data quantitatively. The reason behind this disagreement is that
the dilute flow assumption on which this argument is built breaks down as a
granular shock wave forms in front of the obstacle. More specifically, the
shock wave change the grains impact velocity at the obstacle, decreasing the
overall net lift obtained from a very dilute flow.Comment: 26 pages, preprint format, 15 figures, accepted for publication in
PR
IMDB network revisited: unveiling fractal and modular properties from a typical small-world network
We study a subset of the movie collaboration network, imdb.com, where only
adult movies are included. We show that there are many benefits in using such a
network, which can serve as a prototype for studying social interactions. We
find that the strength of links, i.e., how many times two actors have
collaborated with each other, is an important factor that can significantly
influence the network topology. We see that when we link all actors in the same
movie with each other, the network becomes small-world, lacking a proper
modular structure. On the other hand, by imposing a threshold on the minimum
number of links two actors should have to be in our studied subset, the network
topology becomes naturally fractal. This occurs due to a large number of
meaningless links, namely, links connecting actors that did not actually
interact. We focus our analysis on the fractal and modular properties of this
resulting network, and show that the renormalization group analysis can
characterize the self-similar structure of these networks.Comment: 12 pages, 9 figures, accepted for publication in PLOS ON