Recent simulations of monodisperse colloidal suspensions confined by a spherical cavity demonstrate that both confinement and crowding produce qualitative changes in short- and long-time transport rate processes and equilibrium material properties[1,2,3]. The theoretical and computational framework developed in these studies set the foundation for studying the dynamics of 3D micro-confined suspensions. However, particle polydispersity in size plays a role in many biophysical confined systems such as the interior of eukaryotic cells, but such effects in 3D confinement have received little to no attention in the literature. In the present work, we extend our theory and model to account for size polydispersity. We present the hydrodynamic coupling functions and computational model for a bidisperse suspension of colloids coupled by hydrodynamic interactions inside a spherical cavity. We utilize our model to study the equilibrium structure and short time transport properties of spherically confined bidisperse colloidal suspensions.
 Aponte-Rivera C. and Zia R. N., Phys. Rev. Fluids, vol. 1, p. 023301 (2016).  Aponte-Rivera C., Su Y., Zia R.N., J. Fluid Mech., vol. 836, p. 413-450 (2018).  Aponte-Rivera C. and Zia R. N., Accurate 2-point microrheology inside a spherical cavity. In preparation.