Powdered material flow in the shock wave branching region

The foil-method and metallographic studies of powdered material particle orientation in specimens subjected to loading are used to show that upon regular reflection of colliding shock waves the flow in the region where they branch is homogeneous. A well expressed high-speed flow of material behind the Mach wave from exists for irregular reflections. In the shock wave branching region, two qualitatively different flowregimes are possible: without high-speed flow slippage, and with such slippage. Flow without slippage is found at shock wave amplitudes below some threshold value, dependent on the initial density of the powdered metal. A transition zone in the form of a viscous wake exists at the boundary of the high-speed and low-speed flows. A numerical solution of the model problem of mixing of two homogeneous flows of viscous liquid was carried out. By comparing calculation results to experiments which recorded characteristic viscous wake parameters, it was established that the effective viscosity of a shock-compressed copper powder with dispersion $\le$ 60 $\mu$m comprises $\sim$ 0.01 m$^2$/sec, with the material remaining in the solid state at a density close to that of a monolithic specimen.