LAGRANGE-LAGRANGE TWO-PHASE FLOW SIMULATION OF SALTATION TRANSPORT

The study of bed-load transport is very essential for various hydraulic and environmental problems in coastal engineering discipline. The mode of transport is a function of the bed shearstress, which may occur in saltation or sheet-flow. From low to medium flow tractive forces the bed-load transport occurs in saltation, in which the upper layers of bed grains begin to move due to drag forces initiated between the flow and sediment. On of the major challenge in front of thecoastal engineers is to simulate the bed-load transport due to coastal currents in nearshore area. On the other hand, the numerical modeling of bed-load transport is very complicated because of its hydrodynamic process. This hydrodynamics process usually can be expressed by the fluidsedimentinteractions and intergranular stresses. The two-phase flow model provides an accurate tool in describing this hydrodynamics process and can be described either with a system of Eulerian or Lagrangian coupling of the governing equations of phases. In the Euler-Eulercoupling models, the sediment phase is considered as a continuum phase; hence the probabilistic characteristics of sediment motion are ignored [1]. Euler-Lagrange two-phase flow models,which were proposed to overcome the significant deficiency of Euler-Euler coupling models,also were not completely adequate in describing a proper interaction mechanism between the two phases [2, 3]. In the present work, a numerical model is constructed based on a Lagrange- Lagrange coupling using Smoothed Particle Hydrodynamics1 method.

کلیدواژه ها:

Bed-load Transport ، Saltation ، Two-phase Flow Model ، Smoothed Particle Hydrodynamics (SPH) ، Momentum Transfer