The proposal targets the NRA ROA 2015 within the transformational tools and technologies project subtopic turbulence modeling and simulations. Despite its proven predictive capability large eddy…

This federal contract award, NNX15AU93A, was granted to The Leland Stanford Junior University (Stanford University) by the Shared Services Center, a civilian government agency. The $1.9 million cooperative agreement is focused on validating wall modeling techniques for large eddy simulation (LES) to enable the application of this advanced computational fluid dynamics approach to realistic three-dimensional external aerodynamics configurations at high Reynolds numbers.

The proposed research aims to increase the technology readiness level of wall-modeled LES (WMLES) methods and expand their use for complex aerospace applications. Key aspects include performing the first-ever LES of a wing-body-tail configuration at flight Reynolds numbers using multiple wall modeling approaches, as well as conducting cross-comparisons of these wall models using a common computational infrastructure. This work supports the Transformational Tools and Technologies project under the NASA Transformative Aeronautics Concepts Program. The contract does not have a set-aside designation.

The proposal targets the NRA ROA 2015 within the transformational tools and technologies project subtopic turbulence modeling and simulations. Despite its proven predictive capability large eddy simulation LES has been rarely employed for practical external aerodynamics applications due to prohibitive resolution requirement in simulating high reynolds number wall bounded flows novel wall modeling techniques that have emerged in the last decade have the potential of overcoming this barrier by not resolving the tiny near wall eddie but modeling their effects on the outer layer flow. However wall models have been validated mostly in academic test cases involving simple geometries, and this has contributed to the limited adoption of LES in industry the proposed research will focus on increasing the technology readiness level of wall modeled large eddy simulation wmles methodologies and extending their applicability to realistic three dimensional external aerodynamics configurations. We propose to do two major tasks to achieve this goal. First a LES of a wing body tail configuration at flight reynolds numbers will be attempted for the first time using four recently developed near wall turbulence modeling approaches. If successful, this simulation will demonstrate to the broader engineering community that LES of realistic, complex three dimensional airborne vehicles at operating conditions is possible by leveraging todays cutting edge wall modeling techniques. Second, for the first time, cross comparisons of the wall models will be performed using a common computational infrastructure. So far each wall model has been tested independently of the other models on different canonical test cases and in different codes. We will implement four representative wall models in our in house unstructured flow solver, and perform the model validations using identical test cases. Both canonical and complex wall bounded flows will be considered. This will help US to identify the range of applicability of each model, and to improve the models in a systematic way.