Short-time dynamics and high-frequency rheology of core-shell   suspensions with thin-shells
  Short-time dynamics and high-frequency rheology for suspensions of non-overlapping core-shell particles with thin shells were analyzed. In the thin-shell limit, the single-particle scattering coefficients were derived and shown to define a unique effective radius. This result was used to justify theoretically (in the thin-shell limit) the accuracy of the annulus approximation with the inner radius equal to the effective hydrodynamic radius of the core-shell particle. The two-particle virial expansion of the translational & rotational self-diffusion, sedimentation and viscosity was performed. The virial coefficients were evaluated and shown to be accurately approximated by the effective annulus model, in contrast to the imprecise effective hard sphere model. 
Bogdan Cichocki, Maria L. Ekiel-Jezewska and Eligiusz Wajnryb
cond-mat.soft physics.flu-dyn