2,926 research outputs found
Critical Exponents for Granular Phase Transitions
The solid--fluid phase transition of a granular material shaken horizontally
is investigated numerically. We find that it is a second-order phase transition
and propose two order parameters, namely the averaged kinetic energy and the
averaged granular temperature, to determine the fluidization point precisely.
It scales with the acceleration of the external vibration. Using this
fluidization point as critical point, we discuss the scaling of the kinetic
energy and show that the kinetic energy and the granular temperature show two
different universal critical point exponents for a wide range of excitation
amplitudes.Comment: 6 pages, including 6 figures. Uses Epic and EEpic macros (provided
Competition of mixing and segregation in rotating cylinders
Using discrete element methods, we study numerically the dynamics of the size
segregation process of binary particle mixtures in three-dimensional rotating
drums, operated in the continuous flow regime. Particle rotations are included
and we focus on different volume filling fractions of the drum to study the
interplay between the competing phenomena of mixing and segregation. It is
found that segregation is best for a more than half-filled drum due to the
non-zero width of the fluidized layer. For different particle size ratios, it
is found that radial segregation occurs for any arbitrary small particle size
difference and the final amount of segregation shows a linear dependence on the
size ratio of the two particle species. To quantify the interplay between
segregation and mixing, we investigate the dynamics of the center of mass
positions for each particle component. Starting with initially separated
particle groups we find that no mixing of the component is necessary in order
to obtain a radially segregated core.Comment: 9 pages, 12 figures (EPIC/EEPIC & EPS, macros included), submitted to
Physics of Fluid
Guidelines for More Accurate Determination and Interpretation of Effective Lifetime from Measured Quasi-Steady-State Photoconductance
Presented at the 11th Workshop on Crystalline Silicon Solar Cell Materials and Processes; Estes Park, Colorado; August 19-22, 2001
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