Adaptive Simulation of Flow about the X-38 Vehicle   

Investigator

    R. Meakin, Army AFDD (AMCOM)

Application Overview

    Develop robust adaptive refinement methods for unsteady geometrically complex (moving body) applications that exploit the computational advantages inherent to structured data.

Methodology

    The physical domain of complex problems is decomposed into near-body and off-body regions. The near-body domain is discretized with ``Chimera'' overset grids that need extend only a short distance into the field. The off-body domain is discretized with overset structured Cartesian grids (uniform) of varying levels of refinement. The near-body grids resolve viscous boundary layers and other flow features expected to develop near body surfaces. Off-body grids automatically adapt to the proximity of near-body components and evolving flow features. The adaption scheme automatically maintains solution accuracy at the resolution capacity of the near-body system of grids. The approach is computationally efficient and has high potential for scalability. Grid components are automatically organized into groups of equal size, facilitating parallel scale-up on the number of groups requested. The method has been implemented in the OVERFLOW-D code being developed within the CHSSI CFD-CTA.

Results

    The adaptive refinement capability within OVERFLOW-D has been demonstrated on the X-38 Crew Return Vehicle in a Mach 1.5 freestream, at 15 degrees angle-of- attack, and for a Reynolds Number of 25 million. Reynaldo Gomez of NASA Johnson Space Center provided the near-body grid system and test conditions to the CHSSI CFD-4 software development team.