  Orientation and microstructure are investigated in sheared Brownian
suspensions of hard dicolloidal particles, with the dicolloids modeled as two
fused spheres of varying radii and center to center separations. Two different
particle shapes named homonuclear (aspect ratio 1.1) and fused-dumbbells
(aspect ratio 1.5) were considered. Hydrodynamic interactions between the
particles were computed with a modified lubrication model called Fast
Lubrication Dynamics. Studies were conducted for a wide range of volume
fractions between $0.3 \leq \phi \leq 0.5$ and P\`{e}clet numbers between $0
\leq Pe \leq 1000$. The microstructure was found to be disordered at all volume
fractions, though signatures of weak string like ordering were evident
particularly in $\phi=0.5$ homonuclear suspensions at intermediate to high
shear rates ($Pe$ in the range 10-100). Complex orientation behavior was
observed as a function of shape, shear rates, and volume fractions. At very low
shear rates, random orientation distribution was observed in all cases. At the
highest shear rates, orientation distribution in suspensions of homonuclear
particles exhibited a shift towards an alignment with the vorticity axis at all
volume fractions, while in suspensions of fused-dumbbells it exhibited a shift
away from the vorticity axis at low volume fractions and a negligible shift at
higher volume fractions. The orientation behavior is further characterized by
examining the orientation distribution in the velocity--gradient plane -- in
this case an increased particle alignment with the velocity axis is generally
observed with increasing volume fractions, but not universally with increasing
shear rates. Mechanistic origins for the complex orientation behavior as a
function of shear rate, volume fraction, and particle shape is described.
