Pointwise (United States)

In 2014, the CFD Vision 2030 Report proposed a desired status for aerospace CFD by 2030 that included several challenge problems and a Roadmap describing how to reach this status. Since then, the Report has been used to identify research topics and support funded activities. Further, the AIAA CFD Vision 2030 Integration Committee has been established to further progress toward this vision. A detailed review of the progress made on the milestones identified on the Roadmap was completed in 2020 by this committee and was used to assess the technology readiness level (TRL) of the different milestones. An interpretation of the TRL scale based on publications and level of technology usage was developed and used for assessment consistency. With this information, the Roadmap has been adjusted to reflect the present status of key CFD technology items. Emerging and additional key technologies have been incorporated into the Roadmap. With these modifications, an updated Roadmap is provided that reflects present status of technology development and steps necessary to attain the CFD Vision 2030.

A new mesh adaptation procedure is developed that is well suited to challenging turbomachinery CFD simulations. The automated adaptation creates a mesh that robustly conforms to the underlying geometry, that respects user-defined locally anisotropic boundary layer mesh refinement for efficiency, and that is driven by an adaptation sensor that accurately resolves large as well as subtle secondary flow features. The method seeks to control numerical error in the discrete solution by minimizing the truncation error based on the CFD solver discretization. An adaptation sensor is developed for a node-centred finite volume CFD solver, including control over the rate that the mesh size increases with each adaptation step. The adaptation sensor is used to define a target size field for an updated discrete mesh conforming to the underlying CAD geometry. Examples of mesh adaptation for a heat transfer and a turbomachinery simulation are provided.

The 1st AIAA Geometry and Mesh Generation Workshop (GMGW-1) was held in conjunction with the AIAA Aviation Forum and Exposition 2017 and in collaboration with the 3rd AIAA Computational Fluid Dynamics (CFD) High Lift Prediction Workshop (HiLiftPW-3). As the first AIAA workshop on these topics, GMGW-1's broad objectives were to assess the current state-of-the art in geometry preprocessing and mesh generation technology as well as software as applied to aircraft and spacecraft systems. The workshop was intended to identify and develop understanding of areas of needed improvement in terms of performance, accuracy, and applicability. It was also to provide a foundation for documenting best practices for geometry preprocessing and mesh generation. The genesis of GMGW-1 is found in the indictments levied against geometry preprocessing and mesh generation - not undeservedly - by the NASA CFD Vision 2030 Study. In order to create a reference against which future progress in geometry preprocessing and mesh generation can be measured, the organizers of GMGW-1, with the assistance of the organizers of HiLiftPW- 3, focused GMGW-1 on generation of meshes of the NASA High Lift Common Research Model (HL-CRM). Some of the generated meshes were provided for use by the participants in HiLiftPW-3. All meshes and the processes by which they were generated were analyzed by GMGW-1 as a first assessment of state of the art practices. The results of GMGW-1 added quantitative detail to known problem areas including geometry modeling, data interoperability, and amount of human intervention. They do provide a clear path toward a vision of geometry preprocessing and mesh generation in the year 2030. The next milepost along this path will be a second workshop.

A streamlined upwind Petrov–Galerkin (SUPG)–stabilized finite-element discretization has been implemented as a library into the FUN3D unstructured-grid flow solver. Motivation for the selection of this methodology is given, details of the implementation are provided, and the discretization for the interior scheme is verified for linear and quadratic elements by using the method of manufactured solutions. A methodology is also described for capturing shocks, and simulation results are compared with the finite-volume formulation that is currently the primary method employed for routine engineering applications. The finite-element methodology is demonstrated to be more accurate than the finite-volume technology, particularly on tetrahedral meshes where the solutions obtained using the finite-volume scheme can suffer from adverse effects caused by bias in the grid. Although no effort has been made to date to optimize computational efficiency, the finite-element scheme is competitive with the finite-volume scheme in terms of computer time to reach convergence.

This paper describes an automatic, complex geometries applicable, unstructured, curved two-dimensional mesh-generation method; it provides virtual boundary-layer-like near-body grids coupled with the smooth progression of offbody grids for viscous flow simulations. This method allows for the generation of near-body and offbody grids in one piece at the same phase to avoid mesh quality problems in transition areas. Different from most curved viscous mesh-generation approaches, this method is direct by using a simple vector-adding approach, which obviates a linear or nonlinear-elasticity analogy but still provides highly probable positive-Jacobian mesh elements. In addition, transformation from linear to curved meshes can be achieved by only deforming the necessary edges of the elements near domain boundaries while retaining the remaining noncurved edges to benefit the numerical simulation solvers.

A Streamlined Upwind Petrov-Galerkin (SUPG) stabilized finite-element discretization has been implemented as a library into the FUN3D unstructured-grid flow solver. Motivation for the selection of this methodology is given, details of the implementation are provided, and the discretization for the interior scheme is verified for linear and quadratic elements by using the method of manufactured solutions. A methodology is also described for capturing shocks, and simulation results are compared to the finite-volume formulation that is currently the primary method employed for routine engineering applications. The finite-element methodology is demonstrated to be more accurate than the finite-volume technology, particularly on tetrahedral meshes where the solutions obtained using the finite-volume scheme can suffer from adverse effects caused by bias in the grid. Although no effort has been made to date to optimize computational efficiency, the finite-element scheme is competitive with the finite-volume scheme in terms of computer time to reach convergence.