Scalar PDF and velocity-scalar PDF modelling of the bluff-body stabilised flame HM1 using ILDM

Abstract

-Velocity-scalar and scalar PDF results are compared for the bluff-body stabilised flame HM1 using ILDM chemistry based on mixture fraction, and CO 2 and H 2 O mass fractions. The same Reynolds stress turbulence model and the same modified Curl mixing model are used. No effect of radiative heat loss is included. The results for mean velocity and Reynolds stresses are satisfactory and very similar for both calculations. Each PDF modelling approach implies a different closure for the velocity-scalar correlation. In the present calculations this leads to significant differences in the radial profiles of mean scalars and of mixture fraction variance (different scalar flux modelling): velocity-scalar PDF results (differential scalar flux model) are better than scalar PDF results (gradient diffusion). Results in composition space (scatter plots) confirm the higher quality of the velocity-scalar PDF.

On-demand generation of reduced mechanisms based on hierarchically extended intrinsic low-dimensional manifolds in generalized coordinates

“…[34][35][36][37][38][39][40][41][42][43][44][45][46]51] and references therein) and the use of ILDMs as pre-calculated lookup-tables in flame calculations has proven to be an efficient tool (e.g. [47,48]), though there is a major drawback: typically, no a priori knowledge is used about the part of state space accessed by the flame calculation and the pre-calculated ILDM tables have to cover their whole domain of existence (bounded by the mathematical existence and by additional physical constraints like e.g. nonnegative mass fractions [40]).…”