Cartesian Adaptive Mesh Refinement with the HPCMP CREATE TM -AV Kestrel Solver Timothy A. Eymann * DoD HPCMP CREATE-AV Kestrel Team, Eglin AFB, FL 32542 Robert H. Nichols † DoD HPCMP CREATE-AV Kestrel Team, Arnold AFB, TN 37389 David R. McDaniel ‡ and Todd R. Tuckey § DoD HPCMP CREATE-AV Kestrel Team, Eglin AFB, FL 32542 Kestrel version 5.0 allows users to employ a background Cartesian mesh for better resolution of flow fea- tures. The automatic mesh refinement techniques and core solver are extensions of the SAMCart Cartesian flow solver used with the HPCMP CREATE TM -AV Helios code. The primary enhancements are integration under the Common Scalable Infrastructure (CSI), the ability to use implicit time-stepping, and the addition of upwind flux schemes. Within these broad categories, we detail the strategy for multi-solver communication through the PUNDIT domain connectivity software, benefits gained from CSI, and the new algorithm options available to users. Finally, we present several examples that validate the added options and demonstrate the dual-mesh approach on various use cases of interest to the defense acquisition community. I. Introduction V ERSION 5 of Kestrel, the fixed-wing component of the HPCMP CREATE TM -AV program, introduces the ability to run simulations using an adaptive, Cartesian mesh in the farfield. The idea of combining separate mesh types (e.g. structured/Cartesian or unstructured/Cartesian) is often referred to as a dual-mesh paradigm. The benefits of this dual-mesh technique have been well established for rotorcraft simulations using codes such as OVERFLOW 1, 2 and CREATE TM -AV Helios, 3, 4 the rotary-wing CREATE-AV product. The overarching goal of all CREATE software is to put high-fidelity, multi-physics codes into the hands of working-level engineers, giving them the power to identify and correct flaws early in the design cycle when it is much cheaper to address shortcomings. In order to meet this goal, the software must not only be accurate, but must also be as simple and intuitive to use as possible. Kestrel’s design philosophy reflects this drive for simplicity. One barrier the team has identified in legacy software projects is the tendency to write “monolithic” codes that combine all the functions required for a multi-physics com- putational fluid dynamics (CFD) solver within a single code base. While this is a natural way to organize a project, the end result is often a code that is difficult to maintain or extend and software that presents users with an input deck that is very lengthy and confusing. Kestrel’s answer to monolithic code is to break each code function into a well-defined component, which communicates to other components through the Common Scalable Infrastructure (CSI). 5 The three primary components in Kestrel dual-mesh simulations are the near-body solver, KCFD, the domain connectivity com- ponent using PUNDIT, 6 and an enhanced SAMCart Cartesian solver component. The version of SAMCart in Kestrel v5 is an extension of the off-body solver employed by Helios. 7, 8 This paper details extensions to the SAMCart solver as well as the changes required for KCFD and the domain connectivity software to operate under the dual-mesh paradigm. Command and control of dual-mesh simulations within the CSI framework are covered in Section II. Section III provides a brief summary of the methods used to generate and adapt the Cartesian mesh. Section IV follows with a description of the computational algorithms added to facilitate fixed-wing simulations under Kestrel. Finally, Section V presents a selection of cases that highlight various features of Kestrel dual-mesh simulations. * Research Engineer, Department of the Air Force, AIAA Member † Research Professor, University of Alabama at Birmingham, AIAA Associate Fellow ‡ Research Associate Professor, University of Alabama at Birmingham, AIAA Senior Member § Computer Engineer, Department of the Air Force, AIAA Member 1 of 20 American Institute of Aeronautics and Astronautics DISTRIBUTION A. Approved for public release; distribution is unlimited.