OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy, Hypersonics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: To incorporate new mathematical constructs and high-fidelity design tools to predict Fluid-Structure interactions of Army vehicle (tanks and rotorcraft) DESCRIPTION: The United States Army is actively seeking to advance its capabilities in aerodynamic analysis and design for a wide range of vehicles spanning from rotary-wing aircraft to medium/long-range hypersonic projectiles. A critical need to understand and optimize flight characteristics across various mobility applications is behind this initiative. The United States Army has a need to develop high-fidelity, computationally efficient solvers for the aerodynamic analysis and design of vehicles ranging from rotary-wing aircrafts to medium/long-range hypersonic projectiles. The Army has unique gaps in understanding the flight characteristics (e.g., mobility applications, including gas-turbine engine flow and heat transfer analysis for vehicles that include these propulsion systems) and Extreme-event mitigation including air-blast FSI modeling and simulation for Army vehicles and structures. Isogeometric Analysis (IGA) has brought superior accuracy to spatial and temporal discretization in fluid and structural mechanics simulations. Complex-geometry NURBS mesh (Non-Uniform Rational B-Spline Surfaces) generation tools developed in recent years are making IGA simulations more applicable to real-world problems in fluids, structures, and fluid structure interaction (FSI) and thus more practical and widespread. Bringing even higher fidelity and higher efficiency to IGA FSI simulations will require mid-processing tools. The mid-processing tools should include those listed below. i) More effective unstructured IGA discretization and mesh refinement tools, such as T-splines, subdivision, and locally refined B-splines. Correct prediction of hypersonic boundary layer transition locations, turbulent heat fluxes and vortical structures of high-speed wakes are of paramount importance in enabling the prediction of a next generation hypersonic vehicle's performance. In conclusion, enhancing the fidelity and efficiency of IGA FSI simulations represents a critical competency that provides the United States Army with advanced aerodynamic analysis and design capabilities. PHASE I: The Phase 1 effort shall carefully assess the i) More effective unstructured IGA discretization and mesh refinement tools, such as T-splines, subdivision, and locally refined B-splines. ii) Advanced IGA mesh moving tools, such as the method based on fiber-reinforced hyper elasticity, that significantly increase the scope and accuracy of the IGA FSI computations with body-fitted methods. iii) Tools that will make it simpler in fluid mechanics and FSI simulations carried out with the Variational Multiscale (VMS) method to use more sophisticated and better-performing stabilization parameters, such as those targeting IGA discretization. These parameters play a key role in the stability and accuracy of VMS computations. iv) Visualization tools that will give the users a better understanding of the performance of the IGA computational methods they are using and help them steer the simulations to even higher fidelity. One of the Phase 1 outcomes will be outline of Phase 2 schedule for implementation of Advanced IGA mesh moving tools. Another outcome will be a report summarizing the assessments, a plan to move forward, an estimate of the increased fidelity possible through i-iv, or a recommendation for a prioritization of which tools would be most likely to significantly enhance design tools. PHASE II: In Phase II the mid-processing tools itemized below will be developed. Advanced IGA mesh moving tools, such as the method based on fiber-reinforced hyper elasticity, that significantly increase the scope and accuracy of the IGA FSI computations with body-fitted methods. Tools that will make it simpler in FSI simulations carried out with the Variational Multiscale (VMS) method to use more sophisticated and better-performing stabilization parameters, such as those targeting IGA discretization. These parameters play a key role in the stability and accuracy of the VMS computations. Visualization tools that will give the users a better understanding of the performance of the IGA computational methods they are using and help them steer the simulations to even higher fidelity. PHASE III DUAL USE APPLICATIONS: Collaborate with model, software developers, and users on integration of products into a Long-Range Precision Fires application. Optimize toolset to accommodate new advances in the technology delivering high-speed weapons in anti-access/area-denial environments. Transition the technology to an appropriate government agency or prime defense contractor for integration and testing. Integrate and validate the functional aerothermodynamic tools into a real-world development or acquisition program. REFERENCES: T.J.R. Hughes, J.A. Cottrell, and Y. Bazilevs, Isogeometric analysis: CAD, finite elements, NURBS, exact geometry, and mesh refinement , Computer Methods in Applied Mechanics and Engineering, 194 (2005) 4135-4195.; Y. Otoguro, K. Takizawa, and T.E. Tezduyar, Space time VMS computational flow analysis with isogeometric discretization and a general-purpose NURBS mesh generation method , Computers & Fluids, 158 (2017) 189-200.; T.E. Tezduyar, K. Takizawa, and Y. Bazilevs, Isogeometric analysis in computation of complex-geometry flow problems with moving boundaries and interfaces , Mathematical Models and Methods in Applied Sciences, to appear (2023).; E. Wobbes, Y. Bazilevs, T. Kuraishi, Y. Otoguro, K. Takizawa, and T.E. Tezduyar, Advanced IGA mesh generation and application to structural vibrations , to appear as a chapter in Frontiers in Computational Fluid-Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty 2023, Modeling and Simulation in Science, Engineering and Technology, Springer (2023).; T. Kuraishi, Z. Xu, K. Takizawa, T.E. Tezduyar, and S. Yamasaki, High-resolution multi-domain space-time isogeometric analysis of car and tire aerodynamics with road contact and tire deformation and rotation , Computational Mechanics, 70 (2022) 1257-1279.; Y. Bazilevs, V.M. Calo, J.A. Cottrell, J. Evans, T.J.R. Hughes, S. Lipton, M.A. Scott, and T.W. Sederberg, Isogeometric analysis using T-splines, Computer Methods in Applied Mechanics and Engineering, 199 (2010) 229-263.; F. Cirak, M.J. Scott, E.K. Antonsson, M. Ortiz, and P. Schr der, Integrated modeling, finite-element analysis, and engineering design for thin-shell structures using subdivision , Computer Aided Design, 34 (2002) 137-148.; K.A. Johannessen, T. Kvamsdal, and T. Dokken, Isogeometric analysis using LR B-splines , Computer Methods in Applied Mechanics and Engineering, 269 (2014) 471-514.; K. Takizawa, T.E. Tezduyar, and R. Avsar, A low-distortion mesh moving method based on fiber-reinforced hyperelasticity and optimized zero-stress state , Computational Mechanics, 65 (2020) 1567-1591.; Y. Otoguro, K. Takizawa, and T.E. Tezduyar, Element length calculation in B-spline meshes for complex geometries , Computational Mechanics, 65 (2020) 1085-1103. KEYWORDS: Fluid-Structure interactions, hyperelasticity, modeling, design, tools, air vehicles
