Comparison of models for predicting cleaning of viscoplastic soil layers by impinging coherent turbulent water jets

Abstract

Different approaches to model the cleaning of (i) very thin and (ii) thin soil layers by impinging water jets are compared to evaluate their predictive capabilities. Cleaning experiments were performed with coherent 2 mm and 3 mm diameter water jets (Re > 10,000) impinging on flat layers of an insoluble, viscoplastic petroleum jelly. The jelly exhibited creep below the yield stress and Herschel-Bulkley behaviour above it. A two-film shear-driven model for case (i) gave very poor predictive capability, partly due to the complex soil rheology. Case (ii) data were compared to modified versions of the phenomenological model of Fernandes and Wilson (2020), and a fully-coupled CFD model of the liquid and soil motion using the volume of fluid method. The modifications to the former did not improve its accuracy. The latter gave a good prediction of the initial cleaning behaviour for the case considered: the high computational cost precluded extensive testing.