Accession Number:

AD1160615

Title:

Navier-Stokes Characteristic Boundary Conditions (NSCBC) for Direct Simulations of Turbulent Compressible Flows in Athena-RFX

Descriptive Note:

[Technical Report, Technical Report]

Corporate Author:

US Army Combat Capabilities Development CommandDEFENSE HIGH PERFORMANCE COMPUTING MODERNIZATION PROGRAM OFFICE LORTON VAMARYLAND UNIV COLLEGE PARK

Personal Author(s):

• Starr, Spencer
• Rahul, Koneru B.
• Bravo, Luis

Report Date:

2022-02-22

Pagination or Media Count:

27

Abstract:

The Athena-RFX massively parallel solver has been demonstrated over the years for various complex studies involving chemically reacting flows, compressible turbulence, and more recently multiphase turbulent transport. However, one major challenge that remains is the handling of outflow boundary conditions to mitigate the spurious propagation of artificial instabilities. This problem arises due to the application of zeroth or first-order extrapolation at the boundary ghost cells that fail in the presence of large gradients. To address this problem, this report describes the implementation of the Ghost Cell Navier Stokes Characteristic Boundary Conditions GC-NSCBC method to Athena-RFX. The theoretical formulation of the GC-NSCBC method is described in detail along with benchmark cases for 1 a spherical pressure wave and 2 vortex flows with weak and strong circulation intensities. The method is further demonstrated in the turbulent flow regime involving a spatially developing jet that is a canonical model of the US Army Combat Capabilities Development Command Army Research Laboratory Hot Particulate Ingestion Rig. The solutions presented demonstrate that this method is able to successfully mitigate artificial wave instabilities without altering the transport properties. This enables the application of Athena-RFX to a new class of problems involving interactions of turbulent structures near boundaries or time-varying inflow dynamics.

Descriptors:

• fluid dynamics
• computational fluid dynamics
• military research
• three dimensional
• boundary layer
• fluid flow
• transport properties
• compressible flow
• viscous flow
• flow
• simulations
• boundaries
• extrapolation
• high performance computing
• physics laboratories
• turbulence
• department of defense

Subject Categories:

• Fluid Mechanics

Distribution Statement:

[A, Approved For Public Release]