  Laminar fluid-particle flows in bend geometries are present in many
industrial, pharmaceutical, and biomedical applications. Particle deposition
has been studied extensively; however, little attention has been paid to the
effect of particle sedimentation on particle position and deposition in
different pipe geometry combinations. This study presented a comprehensive
analysis of sedimentation effects on particle flow behaviour in 90{\deg}
circular pipe bends of micron particles in laminar pipe flows. Pipe geometry
combinations consisted of eight pipe diameters, nine bend radii, and 30
particle diameters in a range of 1 to 100 {\mu}m. The results demonstrated the
locations of particles that sedimented to the bottom half of the straight pipe
section, and the particle positions upstream from the pipe bend entrance, which
was no longer in a fully developed profile. These new locations represent the
effects of gravity, pulling the particles down. While obtaining these positions
can be found through CFD analysis, we proposed an analytical solution to
predict the particle trajectory from different release locations that would
help to identify the initial particle distribution at locations upstream to the
bend, to obviate the need for long upstream straight pipe sections in the CFD
analysis.
