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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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Development of a Trajectory-Centric CFD-RBD Framework for Advanced Multidisciplinary/Multiphysics Simulation

The desire to model increasingly complex unsteady flow phenomena drives coupling of physics-based disciplinary analysis tools, such as coupled aerodynamics-rigid body dynamics simulations. This paper documents the creation of a framework linking the six-degree-of-freedom trajectory propagator POST2 with NASA’s FUN3D computational fluid dynamics flow solver. Cross-code verification between the framework and a CFD-centric 6DOF code is performed using the Army-Navy Finner projectile experiencing unsteady accelerating flow. Free-flight simulations of an entry vehicle ballistic range test are validated against physical and computational experiments.

Zachary J Ernst↗

Development of a Trajectory-Centric CFD-RBD Framework for Advanced Multidisciplinary/Multiphysics Simulation

The desire to model increasingly complex unsteady flow phenomena drives coupling of physics-based disciplinary analysis tools, such as coupled aerodynamics-rigid body dynamics simulations. This paper documents the creation of a framework linking the six-degree-of-freedom trajectory propagator POST2 with NASA’s FUN3D computational fluid dynamics flow solver. Cross-code verification between the framework and a CFD-centric 6DOF code is performed using the Army-Navy Finner projectile experiencing unsteady accelerating flow. Free-flight simulations of an entry vehicle ballistic range test are validated against physical and computational experiments.

Zachary J Ernst↗

An Overset Grid Motion Driver for Resolving Entry Vehicle CFD Simulations with Large Changes in Wake Orientation

Time-accurate computational fluid dynamics (CFD) simulations using overset meshes can enable reduced computational cost compared to a rigid, monolithic mesh for blunt-body atmospheric entry vehicles. If the vehicle has a significant change in attitude, the high-density region of the overset mesh designed for resolving the subsonic wake can be kept in position as the wake orientation changes relative to the body. Current simulations generally keep the wake mesh fixed in attitude while the body rotates, assuming the wake orientation remains relatively constant. However, changes in the relative velocity over a long-duration simulation or effects of the body geometry can invalidate this assumption. This work presents a method for calculating the desired mesh orientation to resolve a blunt body wake using the atmosphere-relative velocity of the vehicle. A motion driver using these calculations is implemented in a CFD-in-the-loop flight model bridging the FUN3D flow solver and POST2 trajectory propagator. Overset meshing is performed using the Yoga extension for FUN3D. Results are presented for simulations with both overset and monolithic meshes under large changes in relative velocity (and therefore wake orientation). The results demonstrate that the motion driver successfully orients an overset wake mesh to capture the subsonic wake with sufficient resolution despite variable body rotation and body-relative freestream velocity.

CFD↗