Paper Number
CR9 

Session
Computational Rheology

Title
Structural change and oscillating dynamics of colloidal gels under oscillatory shear flow

Presentation Date and Time
October 6, 2014 (Monday) 2:45

Track / Room
Track 4 / Washington A

Authors (Click on name to view author profile)

1. Park, Jun Dong (Seoul National University, School of Chemical and Biological Engineering)
2. Ahn, Kyung Hyun (Seoul National University, School of Chemical and Biological Enigneering)

Author and Affiliation Lines (in printed abstract book)
Jun Dong Park and Kyung Hyun Ahn
School of Chemical and Biological Enigneering, Seoul National University, Seoul, Republic of Korea

Speaker / Presenter 
Park, Jun Dong

Text of Abstract
Oscillating dynamics and rheological behavior of the colloidal gel under oscillatory shear flow have been studied in line with microstructural change by using the Brownian dynamics simulation method. Under oscillatory shear flow, depending on the flow conditions of various strain amplitude and frequency, colloidal gel showed various microstructural changes. As strain amplitude increased, the network structure of the colloidal gel broke into clusters and small flocs accompanying decrease of the average bond number. The microstructural change led to different oscillating dynamics and rheological behavior. They were studied in three flow regions of SAOS (Small Amplitude Oscillatory Shear), intermediate (between SAOS and LAOS), LAOS (Large Amplitude Oscillatory Shear) regions. In SAOS region, no remarkable structural fluctuation was observed. On the other hand, in intermediate region and LAOS region, the structural fluctuations represented by the fluctuation of the average bond number were observed during the oscillation cycle. The observed structural fluctuations at each region indicated different oscillating dynamics. At each region, different stress response was observed as well as the oscillating dynamics. The complex stress responses were analyzed through the stress decomposition method which decomposes the stress response into elastic and viscous components. Associating the oscillating dynamics and the stress response to the microstructure, characteristic behavior of colloidal gel at three different flow regions of SAOS, intermediate, LAOS was discussed.