1. By Arseniy Kotov CAL POLY San Luis Obispo, Aerospace Engineering Intern at Applied Modeling & Simulation Branch Mentors: Susan Cliff, Emre Sozer, Jeff Housman, Shayan-Moini Yekta and Cetin Kiris CFD Support for Delta Wing Fuselage Sonic Boom Analysis Using LAVA AMS Seminar | August 15 th, 2013 | NASA Ames Research Center, CA

2. 2 Delta Wing Fuselage Analysis with LAVA Perform validation study for an unstructured flow solver (LAVA) with Delta Wing Fuselage configuration Explore best practices for gridding techniques Perform Grid sensitivity analysis Compare the Inviscid vs. Viscous result Compare LAVA results against experimental data and other CFD solutions MαH (in) ᶲ 1.70.24424.860.156 1.7-0.20124.7529.970 1.7-0.18524.7560.056 1.7-0.17824.6989.870 1.70.70621.330.253 1.72.36825.210.334 1.73.90325.490.687 1.71.75132.100.378 1.73.10532.330.236 Delta Wing Fuselage (DWF) Programs used for this study: Gridding Pointwise, STAR-CCM+ Flow Solver LAVA Post Processing VisIt, Tecplot Reynolds number (per inch): 352000

3. 3 Grid Topology

4. Developing a Near-Field Cylindrically-Shaped Mesh Refine Sonic Boom Region of Influence Prescribed by: x1, x2, ry1,ry2, rz1, rz2, M,  Refine Sonic Boom Region of Influence Prescribed by: x1, x2, ry1,ry2, rz1, rz2, M,  4

5. 5 Gridding – Pointwise Curvature-aligned, anisotropic mesh for the elliptical region surrounding the model Unstructured approach for this surface was problematic during extrusion This structured version yields higher quality extrusion Easier to generate structured meshes in Pointwise This surface is exported as a “.stl” file which STAR-CCM+ can read

6. 6 Gridding- STAR-CCM+ Importing the Pointwise outer surface into STAR-CCM+ Extrusion at Mach angle is preformed using cylindrical coordinates based on the formula: This allows us to produce a shock aligned an-isotropic mesh

7. 7 Gridding- STAR-CCM+ Volumetric control was used to refine the region covering the model Upstream and the sting regions were kept relatively coarse This saves grid points while allowing us to have more resolution in areas of interest

8. 8 Launch Ascent and Vehicle Aerodynamics (LAVA) Developed in the Applied Modeling and Simulation Branch at NASA Ames Steady and unsteady multi-physics problems Highly flexible with respect to computational mesh Block-structured Cartesian meshes with Adaptive Mesh Refinement (AMR) immersed-boundary capabilities Structured curvilinear overset meshes Unstructured arbitrary polyhedral meshes Overset coupling of different mesh types Background – LAVA CFD Solver

9. 9 Unsteady compressible Navier-Stokes equations Primarily solved in finite-volume formulation Finite-difference and higher-order options for structured grids Multiple RANS turbulence models (SA, SST) and DES Dual-time stepping for implicit time-integration of time dependent problems Convective flux formulations: Roe, AUSMPW+, central and van Leer Kiris, et al. The LAVA Computational Fluid Dynamics Solver. Submitted abstract, AIAA, 2014. Brehm, et al. Computational Prediction of Pressure Environment in the Flame Trench. AIAA, 2013. Moini-Yekta, et al. Towards Hybrid Simulations of the Launch Environment. ICCFD7, 2012. LAVA CFD Solver (continued)

10. 10 Grid Overview Grid Resolution Cells (million) Boundary Layers Nodes (Sandy Bridge) CoresTurn-over time (mins) Coarse5231016030 Medium12342032060 Fine39364074090 Coarse MediumFine

11. 11 Results – Grid sensitivity study at phi 0.157 o

12. 12 Results –Inviscid vs. Viscous at phi 0.157 o

13. 13 Results – phi 0.157 o

14. 14 Results – phi 29.97 o

15. 15 Results – phi 60.056 o

16. 16 Results – phi 89.870 o

17. 17 Summary All Solvers are working well Experimental data might be lacking STAR-CCM+ will not do angles of attack ANSA might be good future program

18. 18 Further CFD simulations will be run with different geometries 1021 body 1043 body More in depth comparisons with multiple flow solvers LAVA OVERFLOW USM3D Future Work