We aim to conduct an in-depth study of the rheology and flow dynamics of foams and bubble suspensions in Newtonian liquids with gas volume fraction in the range 0 to 75% and to apply the results to the flow of vesicular magmas and lavas in various confined and unconfined geometries. We will determine shear and bulk viscosity and viscoelastic properties as a function of bubble concentration and size-distribution. Foam breakdown under shear, flow down slopes and along pipes will be investigated by experiments and numerical models. Results will be applied to magma flow along dykes and up conduits and lava flows down slopes