The effects of a mass tracer (Intruder) on the response of a bed of monodisperse granular materials to vertical sinusoidal vibration

Date

4-2014

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Junius Andre F. Balista

Abstract

Previous studies on Brazil Nut Effect (BNE) mainly focused on intruder dynamics. Here, we considered primarily the characteristics of the granular bed. We determined the effect of single larger grain (intruder) on the behavior of a bed of smaller grains under vertical sinusoidal vibration. In particular, the variations in expansion of the granular bed and spread in vertical position of individual grains as a function of a dimensionless acceleration Γ, were measured for two cases: with and without the intruder. Three intruders of different sizes were introduced separately. The vibration, whose intensity ranges from Γ = 0 to 14, was generated using a stereo speaker, and the motion of the smaller grains were recorded using a video tracker. Without the intruder, the expansion of the granular bed increased at a decreasing rate for the range of Γ from 0 to 2, then saturated to a certain value thereafter. With Intruder A (diameter ratio Φ = 2.65, density ratio ρr = 0.80), the expansion as a function of Γ is the same as that of the monodisperse case, except that it is slightly shifted upward. The same can be said on the expansion due to Intruder C (Φ = 3.99, ρr = 0.66), except that the shift relative to the monodisperse case is more significant. In contrast, with Intruder B (Φ = 3.28, ρr = 0.73), the expansion of the granular bed is relatively larger from Γ = 0 and gradually decreases at a decreasing rate for the range of Γ from 0 to 2, then thereafter saturated to the same saturation value as that of the case without the intruder. Given the inconsistency of the effect of Intruder B with those of Intruders A and C, we cannot yet conclude on the dependence of expansion on diameter and density of the intruder. However, the presence of the intruder clearly enhances the expansion of the granular bed. These results, validated by the spread of the vertical positions of the individual grains, suggest that the intruder enhances the efficiency of the transmission of the input energy from the container to the smaller grains thereby increasing scattering and expansion. This result is consistent with BNE models which picture intruders as pistons pushing smaller grains out of the way.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 P51 /M37

Document Type

Thesis

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