Papers & Reports 2025

Uncertainties in asteroid properties and entry parameters can lead to large ranges for asteroid damage and risk estimates. NASA's Probabilistic Asteroid Impact Risk (PAIR) model uses a Monte Carlo framework to assess possible damage across these potentially wide input ranges. In this work, a value-of-information study is conducted to determine the benefit to risk knowledge from asteroid property and entry parameter refinements resulting from additional information sources.
Risk Knowledge Improvement from Additional Information for the PDC25 Hypothetical Impact ScenarioActa Astronautica, vol. 240, March 2026.

Analyzing iced wing aerodynamics is important for ensuring aircraft safety. However, simulating iced configurations accurately and efficiently can be challenging due to the complex geometries and flow topologies involved. To investigate these challenges, wall-modeled large-eddy simulation of a swept wing with leading-edge ice buildup is performed using an unstructured Voronoi mesh paradigm and compared to experimental results.
Large-Eddy Simulation of an Iced Swept Wing: A Perspective on the Aerodynamic Effect of Triggering Resolved TurbulenceNASA Technical Memorandum, December 2025.

As a result of a January 2021 Tollgate review, the Advanced Air Vehicles Program approved a new Technical Challenge (TC) to be run out of the Commercial Supersonic Technology (CST) Project. During the 90-day initial baseline Uncertainty Quantification study that followed, a key performance metric and Progress Indicator was created and approved by the Program. The key performance metric was the cumulative error in predicting the certification noise levels of propulsion components appropriate for supersonic flight as they impacted the total aircraft noise.
Prediction Uncertainty Reduction Tech Challenge: Final ReportNASA Technical Memorandum, June 2025.

Asteroid Impact Risk Assessment: Weighing the Potential DamageInternational Asteroid Day, Cranfield University, England, June 30, 2025.

In preparation for the Tiltwing Test Rig experiment at NASA Langley's 14- by 22-Foot Subsonic Tunnel, a series of CFD simulations are being run using OVERFLOW to better understand the physics involved. The first study focuses on determining the best actuator disk model to use for the proprotors. The second is a study of the aerodynamic effect of varying the proprotor turning direction, while the third study looks at the effects of changing the flap deflection angle.
Pre-Test CFD Analyses for the Tiltwing Test Rig ExperimentAIAA Aviation Forum, Las Vegas, NV, July 21-25, 2025.

The Dragonfly rotorcraft lander, NASA’s New Frontiers mission to Titan, will perform the critical Preparation for Powered Flight (PPF) phase following atmospheric entry and parachute descent. This phase ensures the lander transitions safely and stably from passive descent to autonomous powered flight. To better understand the complex aerodynamic environment during PPF, this study presents high-fidelity computational fluid dynamics simulations using NASA’s OVERFLOW solver.
High-Fidelity Simulations of a Dragonfly Lander Test Article in the National Full-Scale Aerodynamics ComplexAIAA Aviation Forum, Las Vegas, NV, July 21-25, 2025.

The Amplification Factor Transport and Medida-Baeder’s local correlation-based transition models are extended to support crossflow-induced transition in NASA’s OVERFLOW CFD code. The algebraic crossflow correlations use helicity as an indicator of local crossflow intensity within the boundary layer. The implementation of these models is validated against standard test cases of crossflow-dominated transition: NLF(2)-0415 45° swept airfoil and TU Braunschweig sickle wing. The full-scale XV-15 rotor is simulated in low- and high-thrust conditions to evaluate the impact of crossflow transition in the prediction of rotor performance. A comparison is established between the fully-turbulent, baseline transition, and crossflow-extended transition models.
Prediction of Laminar-to-Turbulent Transition for the XV-15 Hovering Rotor Flows Using a Crossflow ModelAIAA Aviation Forum, Las Vegas, NV, July 21-25, 2025.

NASA sample return missions must satisfy backward planetary protection requirements which include the need to assure robust containment. In the unlikely event that the vehicle impacts a hard surface, or a damaged vehicle lands at higher-than-predicted velocity, the heat shield may break and potentially cause debris to impact the Secondary Containment Vessel which houses the samples. This paper describes a set of hydrocode simulations of potential debris items striking the Secondary Containment Vessel, to show that the 2023 design can withstand such impacts and the risk of loss of containment is negligible except at impact velocities in excess of 200 m/s.
Hydrocode Simulations of Debris Impacts on the Secondary Containment Vessel During Landing of the Mars SampleJournal of Space Safety Engineering, vol. 12, issue 2, June 2025.

We present a detailed study of how photospheric magnetic fields affect properties of the transition zone and corona, based on an analysis of 3D radiative MHD simulations made with StellarBox. In this presentation, we discuss a heating mechanism of the chromosphere and low corona originating in the transition zone.
Sources of Coronal Heating and Formation of Solar Wind Switchbacks as Revealed by 3D Radiative MHD Simulations246th Meeting of the American Astronomical Society, Anchorage, AK, June 8-12, 2025.

The polar regions of the Sun are of great interest because of the correlation between the polar magnetic flux at a solar minimum and the strength of the following activity cycle. The current observational capabilities allow us to observe the polar regions only twice per year when the rotation axis of the Sun has a maximum inclination to the Earth’s orbit. In this presentation, we discuss recent achievements in 3D radiative hydrodynamics imulations of the subsurface and surface dynamics in the high-latitude and polar regions, assuming the Carrington rotation rate and the rotation rates from helioseismic inferences and surface observations.
Revealing the Surface and Subsurface Dynamics of the Sun's Polar Regions with Observations and 3D Radiative Hydrodynamic Modeling246th Meeting of the American Astronomical Society, Anchorage, AK, June 8-12, 2025.

Ingenuity has sustained an astonishing 72 flights on Mars. The small helicopter proved that nonterrestrial powered flight is possible, even on planets with thin atmospheres. However, on dusty planets, the increase in rotor thrust due to increased weight poses a potential challenge. Dust clouds could form during takeoff and landing due to rotor wash, a phenomenon referred to as brownout. This work evaluates the effectiveness of existing numerical simulation models in predicting the severity of this phenomenon for planetary rotorcraft.
Planetary Helicopter Brownout Simulation of Inginutiy Using a Eulerian Dust Transport ModelAIAA Journal, vol. 63, issue 10, October 2025.

Uncertainty Quantification with QUEST: Toward En-Route Noise Certification-by-AnalysisRCA High Fidelity CFD Workshop, Lockheed-Martin Center for Innovation, Suffolk, VA, May 21, 2025.

Uncertainties in asteroid properties and entry parameters can lead to large ranges for asteroid damage and risk estimates. NASA’s Probabilistic Asteroid Impact Risk (PAIR) model uses a Monte Carlo framework to assess possible damage across these potentially wide input ranges. In this work, a value-of-information study is conducted to determine the expected benefit to risk knowledge from asteroid property and entry parameter refinements resulting from additional information sources.
Uncertainty Effects from an Asteroid Risk Assessment Perspective for the PDC25 Impact Scenario9th International Academy of Astronautics (IAA) Planetary Defense Conference, Stellenbosch, South Africa, May 5-9, 2025.

Coupled Radiation-Hydrocode Predictions of Thermal and Blast Damage for PDC259th International Academy of Astronautics (IAA) Planetary Defense Conference, Stellenbosch, South Africa, May 5-9, 2025.

High-End Computing Enables Discovery at NASAAmes Partnership Days, NASA Ames Research Center, CA, April 29, 2025.

AI at NASA Ames: SupercomputingAmes Partnership Days, NASA Ames Research Center, CA, April 29, 2025.

Advanced ComputingAmes Partnership Days, NASA Ames Research Center, CA, April 29, 2025.

Science Data Processing with High-End ComputingAmes Partnership Days, NASA Ames Research Center, CA, April 29, 2025.

Visualization & Data Analysis at the NASAmes Partnership Days, NASA Ames Research Center, CA, April 29, 2025.

This paper presents a high-fidelity aeropropulsive assessment of the SUSAN Electrofan's distributed electric propulsion (DEP) and boundary layer ingestion (BLI) aft fuselage turbofan technologies. This is achieved through the application of computational tools for aerodyanmic and aeropropulsive design and analysis based on the Reynolds-averaged Navier-Stokes (RANS) equations.
High-Fidelity Aeropropulsive Assessment of Distributed Electric Propulsion and Boundary Layer Ingestion for the SUSAN Electrofan AIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Hybrid- and all-electric aircraft concepts use electric motors for power rather than a conventional jet engine. Electric propulsors open the door to new ways to synergistically integrate the propulsion system with the airframe. For example, many small electric propulsors can be distributed along the wing to increase the effective bypass ratio for better overall efficiency. Furthermore, these propulsors can be attached to the wing surface for boundary layer ingestion (BLI) to further the efficiency gains.
High-Fidelity Aeropropulsive Optimization of a Mail-Slot Distributed Electric Propulsion System for the SUSAN ElectrofanAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

A multidisciplinary design optimization methodology to directly minimize the ground-level noise generated by the sonic boom of a high altitude supersonic body is presented. A Cartesian Euler flow solver is coupled with an atmospheric propagation tool to create a ground-noise analysis capability for supersonic bodies.
Sonic Boom Ground Noise Minimization via the Adjoint Method AIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Wall-modeled large-eddy simulation (LES) of a swept wing with leading-edge ice buildup is performed using three mesh paradigms and associated flow solvers and compared to experimental results. The study focuses on an 8.9% scale model of the CRM65 swept wing featuring both high-fidelity and smooth leading-edge ice shapes. The assessment is conducted using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) framework using the three actively supported meshing paradigms in LAVA: structured curvilinear overset, unstructured, and Cartesian.
Wall-Modeled LES of a Swept Wing With Leading-Edge Ice Using LAVA Curvilinear, Unstructured, and Cartesian SolversAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

This paper establishes a method to create surface pressure databases that allow for uncertainty quantification. Aerodynamic databases are critical products for launch vehicles and other aeronautical systems, and surface pressure databases are one such database that constains large quantities of data. The focus of this work is the relationship between the integrated force and moment database and the surface pressure database.
Copula-Based Method to Generate Consistent Surface Pressures Under UncertaintyAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Wall-Modeled Large Eddy Simulation (WMLES) studies for the 5th AIAA High-Lift Prediction Workshop (HLPW5), conducted using the Launch Ascent and Vehicle Aerodynamics (LAVA) unstructured solver, are presented. The numerical methods, modeling approaches, and meshing strategies are described. A subset of the results for workshop cases 2 and 3 is discussed, with comparisons to available experimental data and insights gained through grid sensitivity studies.
LAVA WMLES Results for the 5th High-Lift Prediction WorkshopAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

A new grid topology approach suitable for body-fitted structured grids is presented to time-accurately simulate the deployment of parachutes from start. The goal is to provide an alternative efficient body-fitted structured grids to Cartesian/unstructured grids for more accurate modeling of turbulent flows. Time-accuracy essential for deployment is maintained, unlike in the quasi-steady loose coupling methods used elsewhere with Cartesian/unstructured grids.
A Body-Fitted Structured Grid Approach to Simulate Breathing Mode Oscillations During Parachute DeploymentAerospace Science and Technology, vol. 156, January 2025.