Many of the hybrid RANS/LES turbulence CFD models suffer from an issue known as the grey area problem. This aspect concerns the transition region between the RANS and LES modes of such hybrid methods. The predictive accuracy of the hybrid methods tends to degrade under certain conditions of flow especially involving shallow regions of boundary later separation and reattachment. To enable improved predictions of the aerodynamics and flow behavior in high Reynolds number industrial flow problems using hybrid RANS/LES approach, the foundation for the SBIR technology successfully established in Phase I in the form of a Synthetic Turbulence Generation (STG) and an Artificial Acoustic Liner (AAL) software module, will be enhanced and matured into a production-ready software toolkit in Phase II. The Phase I of the SBIR pursued several tasks to demonstrate the feasibility of software module for Synthetic Turbulence Generation (STG) that can interface with any of the NASA’s CFD solvers to inject acoustically adapted turbulence at a hybrid RANS/LES interface. In the proposed Phase II, several modeling upgrades will be made to the STG software module to realize rapid recovery of realistic turbulence and minimize the generation of acoustic fluctuations at the hybrid interface. By leveraging on the successes of Phase I of this SBIR, the toolkit will be demonstrated for flow analysis of benchmarked complex test cases. At the conclusion of the proposed SBIR, we will be delivering NASA a STG-AAL Software Toolkit, which is an integrated, well-validated, generalized software toolset with well-established Application Program Interfaces (API) to major CFD codes used by NASA (FUN3D, LAVA, and OpenNCC, etc.). The toolset will be validated and evaluated for a range of RANS and LES model combinations applied to complex test cases.
This product (i) addresses NASA's core needs for enhanced STG generation capabilities for use in conjunction with hybrid RANS/LES modeling of complex flow systems and (ii) provides expertise and methodologies in leveraging the higher-fidelity product capabilities in the analyses of complex flow problems such as aircraft wing design concepts. The advanced capability will be interfaced with NASA CFD code of choice and the framework will be demonstrated within the context of design evaluation of complex flow configurations.
The commercial market for our product includes well established and popular CFD software vendors such as ANSYS, Siemens, and Metacomp, the developers of Fluent, STAR-CCM, and CFD++, respectively. Each of these CFD packages feature a wide number of modeling options to which the respective companies always seek to add.