Numerical modeling of the deposition of combustion-generated soot particles on cold wall surfaces

The build-up of soot deposits on cold wall surfaces is a problem of unknown significance for combustion applications. Soot deposits are due to thermophoretic transport and are generally ignored in theoretical and numerical analysis. We examine here the relationship between the rate of soot deposition and the wall convective heat flux, using both Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES), and a semi-empirical soot model. The soot model adopts a Eulerian approach in which the material properties for thermophoretic transport are independent of particle size. Numerical simulations are performed using two advanced research codes, les3d-mp and AVBP; the DNS of a laminar wall diffusion flame provides insights into the dynamics of soot deposits and leads to the development of a simple soot deposition model for wall-modeled LES. The performance of the subgrid-scale soot deposition model is then evaluated in LES of a soot-laden turbulent channel flow by comparing results from wall-resolved LES and wall-modeled LES. Initial results are encouraging and work is in progress to extend the present study to the case of turbulent non-premixed wall flames.