In-Situ Adaptive Manifolds Beyond Two-Stream, Uni-Modal Turbulent Combustion

Turbulent reacting flow simulation faces dual challenges due to the broad range of scales as well as the high-dimensionality of the thermochemical state. Manifold-based combustion models reduce the computational cost imposed by those challenges by projecting the thermochemical state onto a lower-dimensional manifold. In-Situ Adaptive Manifolds (ISAM) computes solutions to manifold equations 'on-the-fly' and stores the solutions for reuse by In-Situ Adaptive Tabulation (ISAT) with demonstrated computational cost and memory savings for uni-modal combustion processes featuring two inlet streams over the traditional method of precomputing and pretabulating manifold solutions. In this work, the ISAM approach is further generalized and demonstrated. First, manifold-based models have traditionally been limited to two-stream combustion. Developments of a model for three-stream combustion and beyond are discussed and demonstrated in Large Eddy Simulation (LES). Second, manifold-based models have traditionally presumed a single asymptotic combustion mode. Developments of a model for mode-agnostic manifold-based models are also discussed and demonstrated in LES including the effects of the cross-dissipation rate between the mixture fraction and the generalized progress variable.