Study of the velocity of artificial mudflow on a laboratory stand

Abstract

In August 2020, an experiment was conducted to measure the velocity of an artificial coherent mudflow on a laboratory stand. The stand is a rectangular cross-section tray with a length of 3.0 m, a width of 0.25 m, a depth of 0.25 m, slope – 29°. 4 racks were installed in the tray to measure the hydrodynamic pressure of the mudflow. The movement of the mudflow was filmed by a high-speed video camera. Velocity of artificial mudflow were measured. Most of the mudflow mixture soil is made up of particles less than 0.25 mm in size (34%). The density of the prepared mudflow mixture was 1 880 kg/m3. Density of mudflow deposits 2 040 kg/m3. Despite the small values of the Reynolds number, the turbulent movement of the mudflow was observed. Comparison of the results of the measured mudflow velocities with the velocities calculated by different methods of calculating the mudflow velocity based on the structure of the Shezi formula (for Newtonian fluids) showed a strong variation of the calculated values. The methods either greatly overestimate or, on the contrary, greatly underestimate the measured values. This is probably due to the fact that the connected mudflow is not a Newtonian fluid, but a non-Newtonian fluid. The closest physical analogue of a connected mudflow is a pseudoplastic (non-Newtonian) fluid whose viscosity decreases with increasing shear stress. As a physical model of a connected mudflow, it is advisable to use the Bingham fluid model, the flow of which is similar to the flow of coherent debris-flows and mudflows