Mesh Adaptation and Shape Optimization on Unstructured Meshes

In this SBIR CRM proposes to implement the entropy adjoint method for solution adaptive mesh refinement into the Loci/CHEM unstructured flow solver. The scheme will initially be developed and tested for ideal gases and will then be extended to encompass mixtures of thermally perfect/calorically imperfect gases. This approach will use the current remeshing algorithm in Loci/CHEM which utilizes nonstandard general polyhedral elements. The main objective is to provide a robust mesh adaptation scheme that will improve simulation accuracy while reducing overall computational costs. The principal incentive to NASA is to make large-scale, complex flow simulations more accurate and affordable so that their benefits can be fully realized within the design cycle. During Phase I we will perform mesh adaptations for a number of geometries and flow conditions of interest to NASA. We will use these simulations to evaluate the robustness and effectiveness of the new adaptation scheme to improve accuracy, and reduce overall computational cost. During Phase II we will implement a full adjoint scheme into Loci/CHEM. This is a natural extension of Phase I, and will not only allow for complete output-based mesh refinement capability, but will also allow Loci/CHEM to be used for uncertainty estimation and as a shape/geometry optimization tool. The combination of solution adaptive mesh refinement, shape optimization, and uncertainty estimation will provide NASA with a high-confidence, predictive tool for development and assessment of innovative aerodynamic concepts over a wide range of flight regimes.

NASA applications for the Loci/CHEM CFD solver that utilizes the proposed Adjoint methodology span all centers and all programs that incorporate Computational Fluid Dynamics in the design process for space and land vehicles. The highly efficient and accurate solver requires minimal additional computational expense and allows for higher fidelity aerodynamic (force and moment) internal and external predictions for launch vehicles through all ranges of the flight trajectory. The increased accuracy translates to a significant reduction in expensive wind tunnel testing that has traditionally been used for very complex flow scenarios. Examples include plume modeling for jet interaction problems, base heating, plume proximity effects, and modeling of tumble, deceleration, ullage and roll control motors. Another major advantage that this technology offers to NASA is the use of shape optimization features to determine aerodynamic protuberances, nose cones, frustums, control fins, and even optimize nozzle shapes for maximum thrust. Specific applications include NASA's Aircraft Technology Program, Airspace Systems Program, and Subsonic Fixed Wing (SWF) project.

Department of Defense: The Adjoint methodology will aid all Department of Defense (DoD) Project offices that utilize Computational Fluid Dynamics in their design process. Aerodynamic modeling accuracy will be significantly improved for both offensive and defensive missiles, from small man-portable weapons to intercontinental ballistic missile configurations. Additional agencies that will benefit from this technology include (1) Missile Defense Agency for target modeling, (2 Missile and Space Intelligence Center for foreign missile exploitation, and (3) UAV Project Office for low speed modeling of Unmanned Aerial Vehicles. This novel grid adaptation scheme integrated into the Loci/CHEM solver will result in a CFD analysis tool superior to all other solvers currently utilized by these agencies. Commercial Companies: Virtually every engineering company that utilizes CFD for fluid dynamics analysis will be interested in the developed technology. The major target markets include companies that support aerospace, biomedical, industrial, and automotive. The international markets also represent a significant opportunity and will be a focus as the technology becomes productized.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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