Figure 5

(a) Axisymmetric conduit with fixed radius in depth and a local enlargement along a vertical distance z_r (geometry NC1). (b) Conduit with two coaxial cylindrical portions connected by a linearly variable transitional zone of length z_r (geometry NC2). (c) Conduit with a lower axisymmetric portion with fixed radius in depth connected with the surface by a linearly enlarging zone (geometry NC3). (d) Ratio of mass discharge rates versus deepening of fragmentation level (NC1 versus fixed-radius equivalent case). (e) Ratio of exit velocities versus ratio of exit pressures (NC1 versus fixed-radius equivalent case). (f) Ratio of mass discharge rates versus deepening of fragmentation level (NC2 versus fixed-radius equivalent case). (g) Ratio of exit velocities versus ratio of exit pressures (NC2 versus fixed-radius equivalent case). (h) Ratio of mass discharge rates versus deepening of fragmentation level (NC3 versus fixed-radius equivalent case). (i) Ratio of exit velocities versus ratio of exit pressures (NC3 versus fixed-radius equivalent case). Here we present results related to rhyolitic magmas, whereas results related to dacitic, trachytic and phonolites magmas are exhibited in Supplementary Figs S2, S3 and S4, respectively.