Scalar transport closure for a nonlinear reaction problem

Building reduced-order models for turbulent reacting flows is theoretically and computationally challenging as the underlying chemical and transport processes are individually complex and a thorough understanding of the coupled effects of these phenomena remains elusive. Deeper insight into the effects of turbulent transport on reaction dynamics and vice versa is essential for the future design of engineering systems, including those for efficient energy conversion. In this work, a reacting scalar problem that mimics flamelet behavior for premixed combustion is studied in a canonical mixing configuration. The closure terms and closure operators in the context of the Reynolds-Averaged Navier-Stokes equations are developed. We present an assessment of the local and non-local forms of the closure operators capable of capturing unresolved interactions between scalar reactions, building on similar work for non-premixed combustion.