A series of stable and unstable floods has been carried out in a well-characterized, heterogeneous concentric core assembly in order to study predicted recovery mechanisms in such systems. A combination of effluent analysis from the separate layers in the core and computer simulation was used to establish the detailed flows which were subsequently confirmed using computer x-ray tomographic (CT) scanning. Good agreement has been obtained between experiment and theory for unit mobility, and viscous floods in which the respective roles of transverse dispersion and viscous crossflow have been clarified. Some of the main qualitative features found in the unstable displacement (viscous fingering) experiments have also been reproduced using fine grid simulations. CT scanning has been shown to be extremely useful for studying flow mechanisms in systems of this type.