  The need to develop models to predict the motion of microrobots, or robots of
a much smaller scale, moving in fluids in a low Reynolds number regime, and in
particular, in non Newtonian fluids, cannot be understated. The article
develops a Lagrangian based model for one such mechanism - a two-link mechanism
termed a microscallop, moving in a low Reynolds number environment in a non
Newtonian fluid. The modelling proceeds through the conventional Lagrangian
construction for a two-link mechanism and then goes on to model the external
fluid forces using empirically based models for viscosity to complete the
dynamic model. The derived model is then simulated for different initial
conditions and key parameters of the non Newtonian fluid, and the results are
corroborated with a few existing experimental results on a similar mechanism
under identical conditions. Lastly, with a view to implementing control
algorithms we explore accessibility of the system at certain configurations.
