Previous work on the computer simulation of edible fats and oils showed that triglyceride crystalline nanoplatelets (CNPs) aggregated into cylindrical structures dubbed "TAGwoods". This was experimentally verified using Ultra Small Angle X-ray Scattering experiments. In this paper, the aggregation of these TAGwoods was studied using the fluid simulation technique, Dissipative Particle Dynamics. The intent was to predict the TAGwood aggregation structures which arise via the application of a series of shear rates, [small gamma, Greek, dot above]. The effect of shear on TAGwood orientational order was also investigated. Three aggregation regimes were identified: At shear rates below a certain critical value, 0 < [small gamma, Greek, dot above] < [small gamma, Greek, dot above] aggregation was enhanced. The value of the critical shear rate depended on the size of the CNPs. With large CNPs possessing a side length of ∼500 nm, the critical shear rate was [small gamma, Greek, dot above] ≈ 0.6 s. However, if the CNPs were smaller with a side length of ∼100 nm, then [small gamma, Greek, dot above] ≈ 75 s. For shear rates above the critical shear rate, [small gamma, Greek, dot above] > [small gamma, Greek, dot above] aggregation was inhibited. The USAXS data was analyzed using the Unified Fit model and the observations were in accord with the simulation results. Three regimes were identified based on the values of the linear slope P of the USAXS data. P increased as [small gamma, Greek, dot above] increased, indicating increased aggregation of the TAGwoods as the shear rate was increased. P ceased increasing and began to decrease when [small gamma, Greek, dot above] ≈ [small gamma, Greek, dot above]. With further increases in [small gamma, Greek, dot above], P decreased as [small gamma, Greek, dot above] increased further, which is indicative of a decrease in aggregation. The orientational quadrupole order parameter, S = 〈Q〉 = 1/2〈cosθ - 1〉, was computed, where θ is the angle between the axis of the TAGwood and the axis of flow, and showed that, for large [small gamma, Greek, dot above], it achieved a near-maximum value. This indicates that at high shear rates, the long axis of the cylindrical TAGwoods aligns in a direction parallel to that of the fluid flow.

The effects of shear upon the aggregation of solid objects formed from solid triacylglycerols (TAGs) immersed in liquid TAG oils were modeled using Dissipative Particle Dynamics (DPD) and the predictions compared to experimental data using Ultra-Small Angle X-ray Scattering (USAXS). The solid components were represented by spheres interacting via attractive van der Waals forces and short range repulsive forces. A velocity was applied to the liquid particles nearest to the boundary, and Lees-Edwards boundary conditions were used to transmit this motion to non-boundary layers via dissipative interactions. The shear was created through the dissipative forces acting between liquid particles. Translational diffusion was simulated, and the Stokes-Einstein equation was used to relate DPD length and time scales to SI units for comparison with USAXS results. The SI values depended on how large the spherical particles were (250 nm vs. 25 nm). Aggregation was studied by (a) computing the Structure Function and (b) quantifying the number of pairs of solid spheres formed. Solid aggregation was found to be enhanced by low shear rates. As the shear rate was increased, a transition shear region was manifested in which aggregation was inhibited and shear banding was observed. Aggregation was inhibited, and eventually eliminated, by further increases in the shear rate. The magnitude of the transition region shear, γ̇t, depended on the size of the solid particles, which was confirmed experimentally.