An implementation of heterogeneous chemistry into AMReX-based combustion solvers*

The ability to model heterogeneous combustion processes using modern exascale HPC compute architectures holds the potential to address demanding challenges in the energy sector. In this work, the exascale computing project's Pele suite of codes for reacting flows (https://amrex-combustion.github.io/) has been extended to include heterogeneous combustion modelling capabilities. The required heterogeneous chemical kinetics calculations are performed through subroutines that are automatically generated via a reworked implementation of the CEPTR module (https://amrex-combustion.github.io/PelePhysics/Ceptr.html) within the PelePhysics library (https://amrex-combustion.github.io/PelePhysics/). Specifically, CEPTR is equipped to handle three kinds of interface reactions (elementary, surface-coverage-modified, and arbitrary forward reaction rates) along with sticking reactions with and without the inclusion of the Motz-Wise correction. Further, a new surface module has been included in PelePhysics to interface the heterogeneous subroutine library with application codes. In order to verify, validate and benchmark the new additions, a new finite-gap stagnation flow solver with heterogeneous reactions has been developed within the AMReX-combustion framework. The solver numerically solves the steady state stagnation flow similarity equations using the SUNDIALS ARKODE library (https://computing.llnl.gov/projects/sundials/arkode) and is validated through quantitative comparisons of the axial, radial velocity and temperature profiles, along with key species mass fraction profiles along the axial direction against Cantera's impinging jet solver for the case of H2 assisted catalytic combustion of CH4 on Pt. The current work paves the way for enabling 3D heterogeneous combustion simulations within the AMReX-combustion framework.