A Coupled Lattice Boltzmann Model for a Turbulent Sand-Laden Fluid Flow
Talk at the DSFD conference in Brazil
his talk describes a novel numerical modelling approach to simulate a sand-laden, highly turbulent fluid flow, also known as a turbidity current, with the Lattice Boltzmann method. Turbidity currents are sediment laden, highly turbulent submarine flows that are often triggered by catastrophic events like tsunamis or earthquakes. When a tur- bidity current comes to rest, the heaviest, coarsest grains settle first and the finest, lightest grains settle last. These deposits are called Turbidites. Turbidity currents constitute an important factor in the transport of clastic sediments into deep waters . Deposits from such flows are common in the deep water areas throughout the world and many of them constitute important petroleum reservoirs. The modelling and prediction of such deposits are therefore of prime interest both in the academic community and in the industry.Traditionally, turbidity currents have been modelled as a multiphase fluid flow in terms of continuum physics in a partial differential equation setting. Numerous models exist, and they are almost without exception based on traditional computational fluid dynamics (CFD). These are based on the assumption that the fluid and other quantities are in principle a continuum. Although improvement has been made, such models are associated with challenges. It is for instance difficult phenomenologically to describe and model the dynamics, deposition and erosion of sand particles in complex fluid flow from a traditional CFD approach.We will introduce a framework for modelling turbidity currents and turbidite development. The fluid phase is modeled by the Lattice Boltzmann equation, and the sand dynamics is described by the Basset-Boussinesq-Oseen (BBO) for spherical particles in a turbulent fluid. The two phases interact non-linearly through momentum exchange. We will describe basic features of the model and give an overview of the numerical implementation. Current status and outlook on the development process will be reported as well.