Debris Flow and Dam-break surges : Experimental Analysis and two-phase Modelling

To predict floods and debris flow dynamics a numerical model,based on 1D De saint Venant (SV) equations ,was developed.The Mc Cormack-Jameson shock capturing scheme was employed for the solution of the equations ,written in a conservative law form.This technique was applied to determine both the propagation and the profile of a two-phase debris flow resulting from the instantaneous and complete collapse of a storage dam. To validate the model ,comparisons have been made between its predictions and laboratory measurements concerning flows of water and homogeneous granular mixtures in a uniform geometry flume reproducing dam-break waves. Agreements between computational and experimental results are considered very satisfactory for mature (non-stratified) debris flows,which embrace most real cases. To better predict immature (stratified) flows,the model should be improved in order to feature ,in a more realistic way,the distribution ofparticles of different size within the mixture. On the whole, the model proposed can easily be extended to channels with arbitrary cross sections for debris flow routing ,as well for solving different problems of unsteady flow in open channels by incorporating the appropriate initial and boundary conditions.