A Computational Framework for Simulating Flow around Hypersonic Re-Entry Vehicles David Stroh, Anthony Marshik and Gautham Krishnamoorthy, UND Chemical Engineering  Current challenges in computational aerothermodynamics (CA) Efficient generation of unstructured grids to resolve complex geometry Higher order discretization schemes for shock capture Laminar to turbulence transition models Reactions due to dissociation of air Thermodynamic non-equilibrium Spectral radiation Solid deformation due to ablation  Long term goal: Development of add-on modules/functions and best practice guidelines that extends the capabilities of commercial codes to study (CA) problems  Short term goal: Infrastructure: Software licenses (ANSYS FLUENT, ANSYS AUTODYN) Sandia’s DAKOTA tool kit for uncertainty quantification Training of students Software validation of unit problems

Relevance to NASA Directly relevant to the mission of NASA’s Division of Atmospheric and Planetary Sciences. A hierarchial validation approach ranging from unit problems to more complex problems Validations accomplished through comparisons against experimental data and predictions from NASA’s in-house CA codes:  LAURA: Hypersonic flows  ANSYS FLUENT has additional transitional turbulence modeling options  SAS and embedded LES options can resolve global instabilities and turbulent structures  Additional “vibrational temperature” transport equation will be solved  NEQAIR: 1D line-by-line Radiative transport model (> 200,000 spectral intervals)  2D/3D calculations in ANSYS FLUENT account for shock curvature  Tighter coupling with fluid flow  Speed up spectral calculations by reducing it to a few 100 intervals  CMA, FIAT: Material response  Tighter coupling with fluid dynamics  Stronger deformations can be handled through the explicit solver in ANSYS AUTODYN

Accomplishments Training of UGRAs Tasks: Task 1: Laminar flow over blunt cone Task 2: Transitional flow over flat plate Task 3: Surface heat transfer and real gas over a sharp cone Backward and forward facing steps Flow over Mach 20 spherical blunt cone  Task 4: Chemistry  Task 5: Plasma torch problem for Radiative heat transfer (in progress) Task 3 Task 2 Newer transitional models are very promising! Investigating sensitivities to turbulence boundary conditions Spherically blunt cone

Student involvement Use of commercial tools speeds up the learning process. Two UG research assistants (David Stroh and Anthony Marshik) were employed full-time over Summer 2011 – They were trained on the numerical aspects of computational fluid dynamics – They developed a theoretical understanding of boundary layer flows – They developed and demonstrated extensive familiarity with the commercial code ANSYS FLUENT Manuscript in preparation for submission to AIAA Journal of Spacecraft and Rockets

Future plans for proposals NASA NRA – Research Opportunities in Aeronautics Air Force BAA (Aerospace, Chemical and Material Sciences) NSF Fluid Dynamics Program (Feb 2013)