Numerical simulation of a flow over and through porous layers of large porosity

Antoniadis, Panagiotis [UCL] Papalexandris, Miltiadis [UCL]

In this talk we present a continuum model and numerical results for transient flows over and through porous media of large porosity. Our targeted area of application is the simulation of forest fire spread. According to our modeling approach, the vegetation is treated as a rigid porous layer. In the first part of this talk, we briefly discuss the derivation of the continuum model and present an algorithm for its numerical treatment. In the second part of the talk, we present and analyze results from direct numerical simulations for developing flows over porous layers of large porosity. Due to the steep velocity gradients that are developed across the interface between the porous layer and the clear fluid, a Kelvin-Helmholtz instability is onset that leads to the formation of a mixing layer. Important characteristics of this layer such as growth rate, self-similarity and statistics of the fluctuating velocities are presented and discussed.