Complex Three-dimensional Configurations Research Articles

Development and deployment of data-driven turbulence model for three-dimensional complex configurations

Abstract In recent years, the synergy between artificial intelligence and turbulence big data has given rise to a new data-driven paradigm in turbulence research. Data-driven turbulence modeling has emerged as one of the forefront directions in fluid mechanics. Most existing studies focus on feature construction, selection, and the development of modeling frameworks, often overlooking the practical deployment and application of trained models. This paper examines the entire process from model construction to real-world deployment, using data-driven turbulence modeling for high Reynolds number flows over complex three-dimensional configurations as a case study. Key stages include data generation, input-output feature construction, model training, model compilation and optimization, deployment, and validation. We successfully implemented the entire workflow in a heterogeneous supercomputing environment and, through mixed programming techniques, integrated the resulting turbulence model into the Platform for Hybrid Engineering Simulation of Flows (PHengLEI) open-source software framework. This allowed for mixed-precision simulations, with the main equations solved in double precision and the turbulence model in half precision. The new computational framework was validated through large-scale parallel numerical simulations on grids with tens of millions of elements for three-dimensional complex configurations. The results highlight the efficiency of our model deployment, with overall computational efficiency improving by 13.35% and the turbulence model’s solution speed increasing by approximately 3.9 times. The accuracy of the computations was also confirmed, with the average relative error in the lift and drag coefficients calculated by the data-driven turbulence model within 3%. Across various computing nodes, the relative error in the computed aerodynamic coefficients remained within 1%, demonstrating the framework’s scalability. Notably, our contributions have been incorporated as a case study in the latest PHengLEI open-source project5 5 https://forge.osredm.com/PHengLEI/PHengLEI-TestCases/tree/master/Y02_ThreeD_M6_Unstruct_Branch_Ascend. .

Shape Programming of Porous Bilayer Hydrogel Structures

Abstract Shape-programmable materials have garnered significant attention for their ability to morph into complex three-dimensional (3D) configurations under external stimuli, with critical applications in the fields of biomedical engineering, soft robotics, and sensing technologies. A current challenge lies in determining the geometric parameters of the initial two-dimensional (2D) structure and the intensity of the external stimulus required to achieve a target 3D shape. In this work, we introduce a novel inverse design strategy based on hole pattern engineering. Utilizing a temperature-sensitive bilayer hydrogel with differing coefficients of thermal expansion in each layer, we achieve controlled bending deformations by varying the porosity distribution in one of the layers. Drawing on the Timoshenko theory on bimetallic beam, we establish a quantitative relationship between porosity and curvature, allowing for the hole distribution of the initial structure to be tailored to the desired curvature. We demonstrate the efficacy of our inverse design approach with several prototypical 3D structures, including variable-curvature strip and ellipsoidal surface, validated through finite element simulations and experimental trials. This strategy paves the way for advanced fabrication techniques in developing smart materials and devices with programmable shapes.

Improvement and application of local-variable-based transition models to complex three-dimensional configurations

The hypersonic local-correlation-based transition modeling (LCTM) and amplification factor transport (AFT) transition models are extended to crossflow-induced transitions and applied to three-dimensional hypersonic vehicles. A new crossflow Reynolds number correlation is proposed and implanted to an existing hypersonic LCTM to extend it to take account of the crossflow effect. In the hypersonic AFT model, a new transport equation is added to predict the transported crossflow amplification factor. The two improved transition models are first validated using the HIFiRE-5 configuration. The results demonstrate that both transition models predict the transition on HIFiRE-5 with reasonable accuracy. Next, the two models are applied to the X-51A forebody and the X-33 vehicle. The results show that both models are capable of predicting transition behaviors and aeroheating environments on hypersonic complex geometries. The two models also provide reasonable reflections of the effects of various factors that influence transition, including the freestream Reynolds number, turbulence level, and angle of attack.

Performance Testing of Person Passable Openings to Evaluate Accepted Risk

Researchers at Sandia National Laboratories, in conjunction with the Nuclear Energy Institute and Light Water Reactor Sustainability Programs, have conducted testing and analysis to reevaluate and redefine the minimum passible opening size through which a person can effectively pass and navigate. Physical testing with a representative population has been performed on both simple two-dimensional (rectangular and circular cross sections up to 91.4 cm in depth) and more complex three-dimensional (circular cross sections of longer lengths up to 9.1 m and changes in direction) opening configurations. The primary impact of this effort is to define the physical design in which an adversary could successfully pass through a potentially complex opening, as well as to define the designs in which an adversary would not be expected to successfully traverse a complex opening. These data can then be used to support risk-informed decision making.

Dual-band giant spin-selective full-dimensional manipulation of graphene-based chiral meta-mirrors for terahertz waves.

The ability to simultaneous achieve circular dichroism (CD) and wavefront manipulation is extremely important for many practical applications, especially for detecting and imaging. However, many of the previously observed weakness chiral features are limited to nanostructures with complex three-dimensional building configurations, single narrow-band response, and no active tunability, which are getting farther and away from the goal of integration and miniaturization. Here, a platform of bi-layer all-graphene meta-mirrors with spin-selective full-dimensional manipulation is proposed to simultaneously achieve giant dual-band CD response and wavefront shaping, based on the principle of the hybridization coupling. By simply controlling the structural variables of the meta-mirror and the characteristic parameters of graphene, that is, the combination of passive and active regulation, the proposed design can selectively manipulate the polarization, amplitude, phase, and working frequency of the incident circularly polarized wave near-independently. As a proof of concept, we used the meta-mirror to design two metasurface arrays with spin-selective properties for dynamic terahertz (THz) wavefront shaping and near-field digital imaging, both of which show a high-performance dynamic tunability. This method could provide additional options for the next-generation intelligent THz communication systems.

Light-activated shape morphing and light-tracking materials using biopolymer-based programmable photonic nanostructures

Natural systems display sophisticated control of light-matter interactions at multiple length scales for light harvesting, manipulation, and management, through elaborate photonic architectures and responsive material formats. Here, we combine programmable photonic function with elastomeric material composites to generate optomechanical actuators that display controllable and tunable actuation as well as complex deformation in response to simple light illumination. The ability to topographically control photonic bandgaps allows programmable actuation of the elastomeric substrate in response to illumination. Complex three-dimensional configurations, programmable motion patterns, and phototropic movement where the material moves in response to the motion of a light source are presented. A “photonic sunflower” demonstrator device consisting of a light-tracking solar cell is also illustrated to demonstrate the utility of the material composite. The strategy presented here provides new opportunities for the future development of intelligent optomechanical systems that move with light on demand.

Macroscopic Modeling of Water Uptake Behavior of PEDOT:PSS Films.

Poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) is a widely used conductive polymer (CP) for applications in electronic devices. In the context of transparent electrodes or soft actuators, the uptake of water by PEDOT:PSS is an essential element in the performance of the physical system. We study the water uptake of pure films and films treated with ethylene glycol (EG) commonly used to enhance the electrical properties of PEDOT:PSS. Gravimetric analysis was used to investigate the water sorption–desorption of PEDOT:PSS and its change with the EG treatment for a wide range of configurations (thickness, temperature, and relative humidity). We demonstrate that a simple Fickian model cannot correctly represent the experimental results; we therefore introduce a fully coupled reaction–diffusion scheme. This model describes the transport of diffusing molecules into the polymer film, taking into account, in addition to the classical diffusion mechanism, the reaction between the reactive sites of the polymer network and the water molecules. We demonstrate that solvent treatments have a direct influence on the kinetics of the water uptake of PEDOT:PSS films in terms of diffusivity, solubility, and rate of reaction. The proposed model can be used to accurately predict the water uptake of CP films in the case of complex three-dimensional configurations that are needed for the design of complex actuators.

Photodirected Morphing Structures of Nanocomposite Shape Memory Hydrogel with High Stiffness and Toughness.

Shape memory hydrogels have drawn increasing attention in recent years. Practical applications require these hydrogels to have good mechanical properties as well as contactless stimulations to trigger the shape deformations. Here we report a stiff and tough shape memory hydrogel that can transform to various configurations sequentially by phototriggered site-specific deformations. Response of the shape memory hydrogel to near-infrared (NIR) light irradiation was achieved by incorporating gold nanorods (AuNRs) into the glassy gel matrix of poly(methacrylic acid-co-methacrylamide) without compromising the excellent mechanical properties. Owing to the photothermal effect of the AuNRs, the localized temperature rise led to a dramatic decrease in Young's modulus (from 200 to 2 MPa) of the prestretched hydrogel and bending deformation with a programmable direction and amplitude. More complex three-dimensional configurations can be obtained by multidirectional prestretching and shape memorizing the individual parts of the nanocomposite hydrogel. Furthermore, the AuNRs embedded in the gel were aligned along the prestretching direction, leading to anisotropic plasmon resonance. These photomediated programmable deformations of tough shape memory hydrogels should find applications in the biomedical and engineering fields.

Determination of optimum wing spar cross section for maximum fatigue life

Shape optimisation is a nowadays-standard requirement in the design of lightweight structural components. In this paper, optimisation of I-beam cross-section of integral aluminium 2024-T3 wing spar is presented, taking the maximum fatigue life as the criterion. Toward this aim, the extended finite element method (XFEM) was used to simulate crack growth in complex I-beam geometry. The computations were carried out using Morfeo/Crack add-on based on XFEM implementation in Abaqus software. Fatigue lives of wing spars with different sizes of cross section but constant area were compared. Conducted analysis has shown that XFEM seems to be efficient tool for complex three-dimensional configurations optimisation.

An implicit parallel UGKS solver for flows covering various regimes

This paper presents an engineering-oriented UGKS solver package developed in China Aerodynamics Research and Development Center (CARDC). The solver is programmed in Fortran language and uses structured body-fitted mesh, aiming for predicting aerodynamic and aerothermodynamics characteristics in flows covering various regimes on complex three-dimensional configurations. The conservative discrete ordinate method and implicit implementation are incorporated. Meanwhile, a local mesh refinement technique in the velocity space is developed. The parallel strategies include MPI and OpenMP. Test cases include a wedge, a cylinder, a 2D blunt cone, a sphere, and a X38-like vehicle. Good agreements with experimental or DSMC results have been achieved.

A stable partitioned FSI algorithm for rigid bodies and incompressible flow in three dimensions

This paper describes a novel partitioned algorithm for fluid–structure interaction (FSI) problems that couples the motion of rigid bodies and incompressible flow. This is the first partitioned algorithm that remains stable and second-order accurate, without sub-time-step iterations, for very light, and even zero-mass, bodies in three dimensions. This new added-mass partitioned (AMP) algorithm extends the previous developments in [1,2] by generalizing the added-damping tensors to account for arbitrary three-dimensional rotations, and by employing a general quadrature for the surface integral over a rigid body to derive the discrete AMP interface condition for the fluid pressure. Stability analyses for two three-dimensional model problems show that the algorithm remains stable for bodies of any mass when applied to the relevant model problems. The resulting AMP algorithm is implemented in parallel using a moving composite grid framework to treat one or more rigid bodies in complex three-dimensional configurations. The new three-dimensional algorithm is verified and validated though several benchmark problems, including the motion of a sphere in a viscous incompressible fluid and the interaction of a bi-leaflet mechanical heart valve and a pulsating fluid. Numerical simulations confirm the predictions of the stability analysis even for complex problems, and show that the AMP algorithm remains stable, without sub-iterations, for light and even zero-mass three-dimensional rigid bodies of general shape. These benchmark problems are further used to examine the parallel performance of the algorithm and to investigate the conditioning of the linear system for the pressure including the newly derived AMP interface conditions.

Improved grid partitioning algorithms for load-balancing high-order structured aerodynamics simulations

Grid partitioning is very important to achieving the load balancing of parallel structured aerodynamics simulations. For the large-scale parallel computing, the greedy partitioning (Greedy) algorithm may degrade the load balancing performance and even be infeasible for complex grids. In this paper, we propose two structured partitioning algorithms, the multi-dimensional greedy (MG) algorithm and the grid-first multi-dimensional (GFM) algorithm, to mitigate the issue. The new methods satisfy the specific requirement of stencil width in high-order aerodynamics applications. Moreover, the partitioning rules we presented are also satisfied in the new methods for better connectivity among sub-blocks. We validate and evaluate our methods using three realistic and complex three-dimensional structured configurations. Our experimental results with our in-house high-order aerodynamics software show that MG can achieve a speedup of 1.27x, 1.38x, and 1.21x for the three complex configurations, compared to Greedy, while the number for GFM is 1.36x, 1.24x, and 1.22, respectively.

Design of Wing Spar Cross Section for Optimum Fatigue Life

Aircraft structure is the most obvious example where functional requirements demand light weight and strong structures. Shape and sizing optimization are being increasingly used nowadays for designing lightweight structural components. The aim of this paper is to present optimization of I-section integral wing spar made of aluminum 2024-T3. The efficient design, based on optimum fatigue life, was achieved using Extended Finite Element Method (XFEM) and its ability to simulate crack growth in complex geometry. The computations were carried out in Morfeo/Crack for Abaqus software which relies on the implementation of XFEM. Shape optimization of the aircraft wing spar beam was conducted by comparing the fatigue crack growth lives for different cross section shapes, but constant cross section area of the spar. The analysis revealed that XFEM is efficient tool for complex three-dimensional configurations optimization where extended fatigue life is one of the most important objectives.

Photo-responsive liquid crystalline vitrimer containing oligoanilines

Liquid crystalline vitimers (LC-vitrimers) can be easily processed into complex three-dimensional configurations. In this paper, we present a photo-responsive LC-vitrimer by simply introducing a photo-thermal agent aniline trimer into the LC-vitrimer system. As aniline trimer acts as a curing agent, it can be homogeneously dispersed in the material, avoiding aggregation which commonly happens to nano-fillers. As a result, the resultant polymer not only can perform three light-controlled functions (welding, healing and shape memory), but also can be prepared into aligned monodomain LC actuators with strains of about 40%–45%.

Capabilities overview of the MORET 5 Monte Carlo code

The MORET code is a simulation tool that solves the transport equation for neutrons using the Monte Carlo method. It allows users to model complex three-dimensional geometrical configurations, describe the materials, define their own tallies in order to analyse the results. The MORET code has been initially designed to perform calculations for criticality safety assessments. New features has been introduced in the MORET 5 code to expand its use for reactor applications. This paper presents an overview of the MORET 5 code capabilities, going through the description of materials, the geometry modeling, the transport simulation and the definition of the outputs.

Volumetric b-splines shape parametrization for aerodynamic shape design

In this paper, volumetric b-splines are employed to deform the aerodynamic surface. The geometry is enclosed in a volumetric parallelepiped, referred to as control box, which in, essence, is similar to Free Form Deformation (FFD). The use of generic volumetric b-splines requires to calculate the parametric coordinates, but offers some important advantages over other parameterization techniques, such as deformation locality. This parameterization can be applied to the design of complex three-dimensional configurations and also offers the possibility to incorporate the geometric description extracted from the Computational Aid Design (CAD) files, which most frequently are in the form of Non-Uniform Rational B-Splines (NURBS), in what we call multilevel deformation; that is, the control box deforms the NURBS, while the NURBS deforms the computational grid, following the chain rule. In this work, a volumetric b-spline parameterization has been applied in an automatic gradient-based optimization strategy in order to optimize the aerodynamic surface of aeronautical configurations. The design variables are the control points, while the gradients are calculated using the continuous adjoint formulation.

Active materials by four-dimension printing

We advance a paradigm of printed active composite materials realized by directly printing glassy shape memory polymer fibers in an elastomeric matrix. We imbue the active composites with intelligence via a programmed lamina and laminate architecture and a subsequent thermomechanical training process. The initial configuration is created by three-dimension (3D) printing, and then the programmed action of the shape memory fibers creates time dependence of the configuration—the four-dimension (4D) aspect. We design and print laminates in thin plate form that can be thermomechanically programmed to assume complex three-dimensional configurations including bent, coiled, and twisted strips, folded shapes, and complex contoured shapes with nonuniform, spatially varying curvature. The original flat plate shape can be recovered by heating the material again. We also show how the printed active composites can be directly integrated with other printed functionalities to create devices; here we demonstrate this by creating a structure that can assemble itself.

Airfoil Drag Prediction and Decomposition

The accuracy and the consistency of numerical techniques for the prediction of the aerodynamic drag of airfoils in viscous transonic and subsonic flows are explored. Attention is paid to the calculation of the total drag as well as to the decomposition of the drag into its physical components: viscous drag and wave drag. Two different Reynolds-averaged Navier-Stokes solvers are used to generate the flowfield solutions for the NLF(1)-0416 and the RAE 2822 airfoils. The results show that wake integration can produce results comparable with those the often-used surface integral technique, thus demonstrating that wake integration has great potential in simplifying drag calculations for more complex problems such as multielement airfoils or complex three-dimensional configurations

Aerodynamic shape optimization of supersonic aircraft configurations via an adjoint formulation on distributed memory parallel computers

This work describes the application of a control theory-based aerodynamic shape optimization method to the problem of supersonic aircraft design. A high fidelity computational fluid dynamics (CFD) algorithm modelling the Euler equations is used to calculate the aerodynamic properties of complex three-dimensional aircraft configurations. The design process is greatly accelerated through the use of both control theory and parallel computing. Control theory is employed to derive the adjoint differential equations whose solution allows for the evaluation of design gradient information at a fraction of the computational cost required by previous design methods. The resulting problem is then implemented in parallel using a domain decomposition approach, an optimized communication schedule, and the Message Passing Interface (MPI) Standard for portability and efficiency. In our earlier studies, the serial implementation of this design method, was shown to be effective for the optimization of airfoils, wings, wing–bodies, and complex aircraft configurations using both the potential equation and the Euler equations. In this work, our concern will be to extend the methodologies such that the combined capabilities of these new technologies can be used routinely and efficiently in an industrial design environment. The aerodynamic optimization of a supersonic transport configuration is presented as a demonstration test case of the capability. A particular difficulty of this test case is posed by the close coupling of the propulsion/airframe integration.

Aerodynamic calculation of complex three-dimensional configurations

A three-dimensio nal code called ECOPAN, based on an inner Dirichlet boundary condition, has been developed at ONER A. It is currently used to calculate a wide variety of complex aerodynamic configurations. Thus, the future European Ariane 5 launch vehicle has been evaluated in the takeoff phase. It is shown that the change from the automatic version to the Hermes version results in a decrease of the launcher total stability. This decrease is moderated by a favorable interaction of Hermes wake on the lower part of the launcher. A complete Airbus aircraft has been calculated in its takeoff configuration with flaps and slats extended and with a simulation of engine primary and secondary fluxes. The increase in lift due to a plane of symmetry simulating the ground effect has been estimated to be of the order of a few percents, which is in agreement with flight test results. In these two applications the ECOPAN code has demonstrated its versatility, its operational status, and its aptitude to perform parametric analyses in subsonic flow.