Behaviour of an isolated rimmed elliptical inclusion in 2D slow incompressible viscous flow

► Analysis of a rimmed viscous inclusion as a model for clasts with incoherent boundaries. ► FEM models used to determine instantaneous rates of rotation and stretch. ► Initial value ODE approach used to model development with progressive matrix strain. ► ODE model compared to results from high strain numerical models of single inclusions. ► Establishes that a simplified model of rimmed inclusions matches the SPO of natural porphyroclasts.