Viscosity Of Bubble And Crystal-Bearing Silicate Melts

Viscosity of bubble and crystal-bearing silicate melts is studied for isochemical systems in the range of linear and non-linera viscous flow. For crystal bearing melts, effects on viscosity are characterised by volume fraction and morphology of suspended crystals. Whereas dispersed crystals increase the viscosity, shear thinning is attributed to alignment of crystals. In the case of bubble-bearing silicate melts, the importance of bubble deformation is characterised by the capillary number Ca. For Ca>>1 bubbles readily deform and viscosity decreases. Shear thinning caused by bubble deformation is restricted to rheodynamic regimes with Ca values close to unity.