A Novel Approach for the Direct Simulation of Subgrid-Scale Physics in Fire Simulations

Abstract

A Lagrangian framework for computing subgrid-scale combustion physics in Large Eddy Simulations (LES) of fire is formulated and validated. The framework is based on coupling LES formulation, based on the Fire Dynamic Simulator (FDS) with the One-Dimensional Turbulence (ODT) model. The ODT model involves reaction-diffusion and turbulent transport along one-dimensional domains. The one-dimensional domains are attached to the flame brush positions, computed in LES, and are allowed to propagate along its surface. The Lagrangian LES-ODT framework involves various implementations including a) momentum, energy, and species solution along one-dimensional ODT domain, b) Tracking of ODT domains through their anchor points, c) Filtering of ODT solutions on the LES grid, d) Inverse filtering (interpolation) of LES velocity fields in ODT domains, and e) The management of ODT domains at the flow inlets and as they reach the flame tip. Comparison of LES-ODT solutions with FDS solutions shows that the LES-ODT implementation reproduces reasonably well the flame topology and structure.