Dynamics of the boundary-layer structure in a volcanic channel during explosive eruption

The unsteady two dimensional axisymmetric problem about the dynamics of the viscous-melt state and the boundary layer development on the channel wall at the initial stage of the magma-flow formation behind the decompression wave front has been reported. The homogeneous and heterogeneous nucleation of cavitation nuclei, their diffusion and crystallization, determine the entire many sided nature and multiscale nature of the phenomena accompanying the eruption. The melt behind the wave front proves to be in a supersaturated state as a result of which the gas bubbles are nucleated in its volume and grow spontaneously also due to the dissolved gas diffusion. The flow of the magma, which is motionless at the initial moment of time, starts to form behind the decompression wave front. Initially, the channel-relief profile can only enhance this effect.