A multi-code-coupling interface for combustor/turbomachinery simulations

This paper describes the design, implementation and validation of a method to couple multiprocessor solvers whose solution domains share a common surface. Using Message Passing Interface (MPI) constructs, parallel communication pathways are established between various simulation codes. These pathways allow applications to exchange data, synchronize time integrations and reinitialize communication data structures when meshes change their relative positions. At an interface with another simulation code, applications request specific flow variables, typically for a ghost/halo layer of cells or nodes. Numerical estimates of these flow variables are provided by the simulation software on the other side of the interface through three-dimensional interpolation. With an aim at achieving conservative interfacing between applications, particular instances of the requested flow variables and interpolation stencils will be used for different problems. Communication tables are built for processes involved with the exchange of information and all exchanges occur strictly between specific processes, thereby minimizing communication bottlenecks. This paradigm has been used to build a code coupling interface for a three-dimensional combustor/turbine interaction simulation in which a new massively parallel computational fluid dynamic solution procedure for turbomachinery, called TFLO, has been coupled with an unstructured-grid, parallel procedure for combustors, called NCC. Numerical and physical issues regarding the exchange of information as well as the coupling of physics-disparate analyses will be discussed. Several development test cases have been used to ensure the soundness of the communication procedures. A multi-component simulation for a dump combustor/exit duct has been performed as a demonstration of the new interface.