Effect of mechanical vibration on the displacement of fluid deposits

• Main Author: Pung, Rachael Hui Riong
• Other Authors: Chiew Yee Meng
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/67269
• Institution: Nanyang Technological University

The movement of the jaw creates up-down movements in the head and the external auditory canal which disturbs the cerumen deposits (also known as earwax). Aided by this movement and the slope of the ear canal, the cerumen will flow outwards and clear off our ears. The jaw movement is similar to a vibration associated with varying acceleration. Hence, the concept of this study serves to understand the displacement of cerumen-like samples when subjected to different vibration acceleration. Vibrations are delivered through an oscillating speaker surface and the associated acceleration is measured and recorded using an accelerometer. Fluid samples are deposited on a clear surface with indicator lines drawn on a regular grid thereby permitting easy measurement of the fluid displacement. The first aspect of this study aims to understand how different fluids will respond under the same vibration acceleration. The fluids studied are water, moisturiser, Aloe Vera gel and Vaseline. Comparisons of the displacement of different fluids with and without the application of vibration are made. Water deposits showed the greatest change in displacement followed by moisturiser, then gel. The high finite yield stress of Vaseline causes it to behave as a rigid body, and exhibit no movement. The second part of the study involves the use of the gel type fluid to mimic wet soft cerumen to establish its movement under different vibration acceleration. The gel deposit exhibits behaviour that resembles a non-Newtonian fluid. The threshold vibration acceleration for gel deposits to show an increase in displacement due to vibration is found to be 0.4905m/s2. When the gel deposit is subjected to increasing vibration acceleration, the displacements of the deposits are observed to increase at a decreasing rate. It is recommended that more experiments can be conducted to validate the behaviour of the gel at the upper limit of acceleration due to the limited vibration acceleration generated by the speaker surface. The increase in displacement observed can be potentially attributed to the decrease in surface area experienced by the gel deposits that is thrusted upwards thereby increasing the shear stress for downslope movement. This is similar to the behaviour of fluids under vibration. A second possible reason is the outward thrust of the deposits, which subsequently falls downwards to a new position on the inclined slope thereby increasing the displacement observed when the vibration acceleration increases. This second reason is similar to solid movement on an inclined vibrating surface when a certain threshold vibration is attained. Future studies can be conducted to validate the above two proposed reasons for the increase in displacement observed when vibrations are applied to a non-Newtonian fluid.