Realizable Closure for the Orientation Tetrad for Rigid Rod Suspensions
Abstract
The prediction of low-order statistical properties of suspensions and liquid crystalline polymers is often based on a moment equation for the orientation dyad that requires a closure model for the orientation tetrad. A new closure has been developed that retains the six-fold symmetry and projection properties of the exact orientation tetrad. (Petty et al., 1999; Nguyen et al., 2001; Kini et al., 2003). This presentation will summarize recent results obtained by applying the new microstructure theory to a class of rigid rod suspensions subjected to homogeneous shear. In the absence of deformation, the theory predicts the existence of multiple steady states for the microstructure as a consequence of a balance between Brownian motion and an excluded volume potential in orientation space. In the presence of homogeneous shear, the orientation director for relatively concentrated suspensions shows periodic behavior relative to the flow direction. For low strain rates, the orientation director executes a tumbling periodic motion. As the strain rate increases, a wagging periodic motion occurs and, at very high strain rates, a steady alignment of the orientation director relative to the flow direction is predicted.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 2003
- Bibcode:
- 2003APS..DFD.AK008K