An Eulerian-Eulerian model for gravity currents driven by inertial particles

CANTERO, MARIANO I.; BALACHANDAR, S.; GARCÍA, MARCELO

INTERNATIONAL JOURNAL OF MULTIPHASE FLOW

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2008 vol. 34 p. 484 - 501

0301-9322

In this work we introduce an Eulerian?Eulerian formulation for gravity currents driven by inertial particles. The model is based on theequilibrium Eulerian approach and on an asymptotic expansion of the two-phase flow equations. The final model consists of conserva-tion equations for the continuum phase (carrier fluid), an algebraic equation for the disperse phase (particles) velocity that accounts forsettling and inertial effects, and a transport equation for the disperse phase volume fraction. We present highly resolved two-dimensional(2D) simulations of the flow for a Reynolds number of Re 1⁄4 3450 (this particular choice corresponds to a value of Grashof number ofGr 1⁄4 Re2 =8 1⁄4 1:5 Â 106 ) in order to address the effect of particle inertia on flow features. The simulations capture physical aspects oftwo-phase flows, such as particle preferential concentration and particle migration down turbulence gradients (turbophoresis), whichmodify substantially the structure and dynamics of the flow. We observe the migration of particles from the core of Kelvin?Helmholtzvortices shed from the front of the current as well as their accumulation in the current head. This redistribution of particles in the current affects the propagation speed of the front, bottom shear stress distribution, deposition rate and sedimentation. This knowledge is helpful for the interpretation of the geologic record.