Journal articles: 'Aerospace engineering – Simulation methods'

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Dai, Honghua, and Xiaokui Yue. "Preface: Nonlinear Computational and Control Methods in Aerospace Engineering." Computer Modeling in Engineering & Sciences 122, no. 1 (2020): 1–4. http://dx.doi.org/10.32604/cmes.2020.09126.

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Heinz, Stefan, Joachim Peinke, and Bernhard Stoevesandt. "Cutting-Edge Turbulence Simulation Methods for Wind Energy and Aerospace Problems." Fluids 6, no. 8 (August 16, 2021): 288. http://dx.doi.org/10.3390/fluids6080288.

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The availability of reliable and efficient turbulent flow simulation methods is highly beneficial for wind energy and aerospace developments. However, existing simulation methods suffer from significant shortcomings. In particular, the most promising methods (hybrid RANS-LES methods) face divergent developments over decades, there is a significant waste of resources and opportunities. It is very likely that this development will continue as long as there is little awareness of conceptional differences of hybrid methods and their implications. The main purpose of this paper is to contribute to such clarification by identifying a basic requirement for the proper functioning of hybrid RANS-LES methods: a physically correct communication of RANS and LES modes. The state of the art of continuous eddy simulations (CES) methods (which include the required mode communication) is described and requirements for further developments are presented.

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Perfect, P., M. D. White, G. D. Padfield, and A. W. Gubbels. "Rotorcraft simulation fidelity: new methods for quantification and assessment." Aeronautical Journal 117, no. 1189 (March 2013): 235–82. http://dx.doi.org/10.1017/s0001924000007983.

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AbstractFlight simulators are integral to the design/development, testing/qualification, training and research communities and their utilisation is ever expanding. The use of flight simulation to provide a safe environment for pilot training, and in research and development, must be underpinned by quantification of simulator fidelity. While regulatory simulator standards exist for flight training simulators and new standards are in development, previous research has shown that current standards do not provide a fully quantitative approach for assessing simulation fidelity, especially in a research environment. This paper reports on progress made in a research project at the University of Liverpool (Lifting Standards), in which new predicted and perceptual measures of simulator fidelity have been developed. The new metrics have been derived from handling qualities engineering practice. Results from flight tests on the National Research Council (Canada) Bell 412 ASRA research aircraft and piloted simulation trials using the HELIFLIGHT-R simulator at Liverpool are presented to show the efficacy of adopting a handling qualities approach for fidelity assessment. Analysis of the new metrics has shown an appropriate degree of sensitivity to differences between flight and simulation.

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Shi, Renhe, Teng Long, Nianhui Ye, Yufei Wu, Zhao Wei, and Zhenyu Liu. "Metamodel-based multidisciplinary design optimization methods for aerospace system." Astrodynamics 5, no. 3 (September 2021): 185–215. http://dx.doi.org/10.1007/s42064-021-0109-x.

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AbstractThe design of complex aerospace systems is a multidisciplinary design optimization (MDO) problem involving the interaction of multiple disciplines. However, because of the necessity of evaluating expensive black-box simulations, the enormous computational cost of solving MDO problems in aerospace systems has also become a problem in practice. To resolve this, metamodel-based design optimization techniques have been applied to MDO. With these methods, system models can be rapidly predicted using approximate metamodels to improve the optimization efficiency. This paper presents an overall survey of metamodel-based MDO for aerospace systems. From the perspective of aerospace system design, this paper introduces the fundamental methodology and technology of metamodel-based MDO, including aerospace system MDO problem formulation, metamodeling techniques, state-of-the-art metamodel-based multidisciplinary optimization strategies, and expensive black-box constraint-handling mechanisms. Moreover, various aerospace system examples are presented to illustrate the application of metamodel-based MDOs to practical engineering. The conclusions derived from this work are summarized in the final section of the paper. The survey results are expected to serve as guide and reference for designers involved in metamodel-based MDO in the field of aerospace engineering.

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Bieniek, D., R. Luckner, I. De Visscher, and G. Winckelmans. "Simulation Methods for Aircraft Encounters with Deformed Wake Vortices." Journal of Aircraft 53, no. 6 (November 2016): 1581–96. http://dx.doi.org/10.2514/1.c033790.

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Sun, Fuyu, Hua Wang, and Jianping Zhou. "Research and development techniques for early-warning satellite systems using concurrent engineering." Concurrent Engineering 26, no. 3 (April 23, 2018): 215–30. http://dx.doi.org/10.1177/1063293x18768668.

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An early-warning satellite system is a complex project that requires the participation of many aerospace academies and scientific institutions. In terms of software programming, this study proposes a new simulation integrated management platform for the analysis of parallel and distributed systems. The platform facilitates the design and testing of both applications and architectures. To improve the efficiency of project development, new early-warning satellite systems are designed based on the simulation integrated management platform. In terms of project management, this study applies concurrent engineering theory to aerospace engineering and presents a method of collaborative project management. Finally, through a series of experiments, this study validates the simulation integrated management platform, models, and project management method. Furthermore, the causes of deviation and prevention methods are explained in detail. The proposed simulation platform, models, and project management method provide a foundation for further validations of autonomous technology in space attack–defense architecture research.

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Albinsson, Anton, Fredrik Bruzelius, Bengt Jacobson, and Shenhai Ran. "Validation of vehicle-based tyre testing methods." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 1 (June 20, 2018): 18–27. http://dx.doi.org/10.1177/0954407018777581.

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The development process for passenger cars is both time- and resource-consuming. Full vehicle testing is an extensive part of the development process that consumes large amount of resources, especially within the field of vehicle dynamics and active safety. By replacing physical testing with complete vehicle simulations, both the development time and cost can potentially be reduced. This requires accurate simulation models that represent the real vehicle. One major challenge with full vehicle simulation models is the representation of tyres in terms of force and moment generation. The force and moment generation of the tyres is affected by both operating conditions and road surface. Vehicle-based tyre testing offers a fast and efficient way to rescale force and moment tyre models to different road surfaces, in this study the Pacejka 2002 model. The resulting tyre model is sensitive to both the operating conditions during testing and the road surface used. This study investigates the influence of the slip angle sweep rate and road surface on the lateral tyre force characteristics of the fitted tyre model. Tyre models fitted to different manoeuvres are compared and the influence on the full vehicle behaviour is investigated in IPG Carmaker. The results show that by using the wrong road surface, the resulting tyre model can end up outside the tolerances specified by the ISO standard for vehicle simulation model verification in steady-state cornering. The use of Pacejka 2002 models parameterized in a steady-state manoeuvre to simulate the vehicle behaviour in sine-with-dwell manoeuvres is also discussed.

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Huang, Shizhuo, Qian Chen, Yuwei Cheng, Jinyu Xian, and Zhengqi Tai. "Supersonic Combustion Modeling and Simulation on General Platforms." Aerospace 9, no. 7 (July 7, 2022): 366. http://dx.doi.org/10.3390/aerospace9070366.

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Supersonic combustion is an advanced technology for the next generation of aerospace vehicles. In the last two decades, numerical simulation has been widely used for the investigation on supersonic combustion. In this paper, the modeling and simulation of supersonic combustion on general platforms are thoroughly reviewed, with emphasis placed on turbulence modeling and turbulence–chemistry interactions treatment which are both essential for engineering computation of supersonic combustion. It is found that the Reynolds-averaged Navier–Stokes methods on the general platforms have provided useful experience for the numerical simulation in engineering design of supersonic combustion, while the large eddy simulation methods need to be widely utilized and further developed on these platforms. Meanwhile, the species transport models as a kind of reasonable combustion model accounting for the turbulence–chemistry interactions in supersonic combustion have achieved good results. With the development of new combustion models, especially those designed in recent years for high-speed combustion, the turbulence–chemistry interactions treatment for numerical simulation of supersonic combustion based on general platforms is expected to be further mature in the future.

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Cao, Yihua, Kungang Yuan, and Xiaoyong Li. "Computational Methods for Simulation of Flow Around Helicopter Engine Inlet." Journal of Aircraft 43, no. 1 (January 2006): 141–46. http://dx.doi.org/10.2514/1.14679.

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Yoh, Jack J., and Xiaolin Zhong. "New Hybrid Runge-Kutta Methods for Unsteady Reactive Flow Simulation." AIAA Journal 42, no. 8 (August 2004): 1593–600. http://dx.doi.org/10.2514/1.3843.

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Ortega, Enrique, Roberto Flores, and Jordi Pons-Prats. "Ram-Air Parachute Simulation with Panel Methods and Staggered Coupling." Journal of Aircraft 54, no. 2 (March 2017): 807–14. http://dx.doi.org/10.2514/1.c033677.

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Huang, Taiming, Shuya Li, Zhongmin Wan, and Zhengqi Gu. "Investigation of vehicle stability under crosswind conditions based on coupling methods." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 13 (January 17, 2019): 3305–17. http://dx.doi.org/10.1177/0954407018822424.

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In this study, vehicle stability under crosswind conditions is investigated. A two-way coupling method is established based on computational fluid dynamics and vehicle multi-body dynamics. Large eddy simulation is employed in the computational fluid dynamics model to compute the transient aerodynamic load, and the accuracy of the large eddy simulation is validated with a wind tunnel experiment. The arbitrary Lagrange–Euler technique is used in the computational fluid dynamics simulation to realise vehicle motion, and a real-time data transmission method is employed to ensure effective exchange of data between the computational fluid dynamics and multi-body dynamics models. The robustness of the two-way coupling model is verified by changing the position of the vehicle centroid. The results of the two-way and one-way coupling simulations demonstrate that crosswinds significantly affect vehicle stability. There is a clear difference between the results obtained with the two methods, particularly after the disappearance of the crosswind. The main reason for the difference is that the interaction between the transient airflow and the vehicle movement is considered in the two-way coupling method. Therefore, investigations of vehicle stability under crosswind conditions should consider the coupling of transient aerodynamic force and vehicle movement.

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Sorrentino, Assunta, Fulvio Romano, and Angelo De Fenza. "Advanced debonding detection technique for aerospace composite structures." Aircraft Engineering and Aerospace Technology 93, no. 6 (July 19, 2021): 1011–17. http://dx.doi.org/10.1108/aeat-10-2020-0222.

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Purpose The purpose of this paper is to introduce a methodology aimed to detect debonding induced by low impacts energies in typical aeronautical structures. The methodology is based on high frequency sensors/actuators system simulation and the application of elliptical triangulation (ET) and probability ellipse (PE) methods as damage detector. Numerical and experimental results on small-scale stiffened panels made of carbon fiber-reinforced plastic material are discussed. Design/methodology/approach The damage detection methodology is based on high frequency sensors/actuators piezoceramics system enabling the ET and the PE methods. The approach is based on ultrasonic guided waves propagation measurement and simulation within the structure and perturbations induced by debonding or impact damage that affect the signal characteristics. Findings The work is focused on debonding detection via test and simulations and calculation of damage indexes (DIs). The ET and PE methodologies have demonstrated the link between the DIs and debonding enabling the identification of position and growth of the damage. Originality/value The debonding between two structural elements caused in manufacturing or in-service is very difficult to detect, especially when the components are in low accessibility areas. This criticality, together with the uncertainty of long-term adhesive performance and the inability to continuously assess the debonding condition, induces the aircrafts’ manufacturers to pursuit ultraconservative design approach, with in turn an increment in final weight of these parts. The aim of this research’s activity is to demonstrate the effectiveness of the proposed methodology and the robustness of the structural health monitoring system to detect debonding in a typical aeronautical structural joint.

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Scott, Robert C., Anthony S. Pototzky, and Boyd Perry. "Matched-filter and stochastic-simulation-based methods of gust loads prediction." Journal of Aircraft 32, no. 5 (September 1995): 1047–55. http://dx.doi.org/10.2514/3.46835.

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Chauhan, Monika, and Luca Massa. "Large-Eddy Simulation of Supersonic Jet Noise with Discontinuous Galerkin Methods." AIAA Journal 60, no. 3 (March 2022): 1451–70. http://dx.doi.org/10.2514/1.j060424.

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Yoh, Jack J., and Xiaolin Zhong. "New Hybrid Runge-Kutta Methods for Unsteady Reactive Flow Simulation: Applications." AIAA Journal 42, no. 8 (August 2004): 1601–11. http://dx.doi.org/10.2514/1.3844.

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Mi, Kai, Yun Hu, and Chao Yin. "Quality Evaluation for Model Based Definition of Aerospace Products." Advanced Materials Research 945-949 (June 2014): 30–34. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.30.

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With the rapid development of computer aided technology, the application of model based definition (MBD) in the research and development (R&D) processes of aerospace products become more and more widespread. The quality of MBD refers to its ability to meet the requirements of the downstream processes like subsequent design, manufacture, simulation, and inspection etc. Based on MBD’s quality characteristics, such as modeling and simulation quality, design process quality, geometry and topology quality, data quality and data exchange quality, this paper constructs a quality model for aerospace digital products and proposes both qualitative and quantitative quality evaluation methods for MBD of aerospace products.

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Yin, Qiaozhi, Hong Nie, Xiaohui Wei, and Ming Zhang. "Aircraft electric anti-skid braking and combined direction control system using co-simulation and experimental methods." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (May 28, 2019): 173–91. http://dx.doi.org/10.1177/0954410019852825.

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The work reported in this paper concentrates on the design and application of an electric ground control system combining the braking and steering mechanisms on a small unmanned aerial vehicle. A virtual prototype of a small unmanned aerial vehicle is built with a multibody dynamic software LMS Virtual.Lab Motion. An electric anti-skid braking system and a new combined direction control system considering the sensors models are established with MATLAB/Simulink. Optimizations are carried out using a global optimization command patternsearch first and then a local optimization method fminsearch for fine-tuning to design the dynamic allocation for the direction rectifying weight coefficients. Then a co-simulation method is introduced to study the ground maneuver performance so as to investigate the interaction of each subsystem via the interfaces between the two softwares. The anti-skid braking simulation verifies that the aircraft can stop smoothly and efficiently. The combined rectification control simulations in three different conditions verify the system stability and robustness. In addition, an anti-skid braking and a direction-control experiment are conducted. Results show that the experimental results fit well with the simulation and that the yaw angle can be corrected effectively under the designed control systems.

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Thornber, B., and D. Drikakis. "Implicit Large-Eddy Simulation of a Deep Cavity Using High-Resolution Methods." AIAA Journal 46, no. 10 (October 2008): 2634–45. http://dx.doi.org/10.2514/1.36856.

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Khapane, Prashant D. "Gear walk instability studies using flexible multibody dynamics simulation methods in SIMPACK." Aerospace Science and Technology 10, no. 1 (January 2006): 19–25. http://dx.doi.org/10.1016/j.ast.2005.07.009.

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Albinsson, Anton, Fredrik Bruzelius, Bengt Jacobson, and Egbert Bakker. "Evaluation of vehicle-based tyre testing methods." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 1 (March 27, 2018): 4–17. http://dx.doi.org/10.1177/0954407018760953.

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The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.

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Zhang, Yanxi, Fengjiang An, Shasha Liao, Cheng Wu, Jian Liu, and Yipeng Li. "Study on Numerical Simulation Methods for Hypervelocity Impact on Large-Scale Complex Spacecraft Structures." Aerospace 9, no. 1 (December 25, 2021): 12. http://dx.doi.org/10.3390/aerospace9010012.

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This paper aims to study the difference of results in breakup state judgment, debris cloud and fragment characteristic parameter during hypervelocity impact (HVI) on large-scale complex spacecraft structures by various numerical simulation methods. We compared the results of the test of aluminum projectile impact on an aluminum plate with the simulation results of the smooth particle hydrodynamics (SPH), finite element method (FEM)-smoothed particle Galerkin (SPG) fixed coupling method, node separation method, and finite element method-smooth particle hydrodynamics adaptive coupling method under varying mesh/particle sizes. Then based on the test of the complex simulated satellite under hypervelocity impact of space debris, the most applicable algorithm was selected and used to verify the accuracy of the calculation results. It was found that the finite element method-smooth particle hydrodynamics adaptive coupling method has lower mesh sensitivity in displaying the contour of the debris cloud and calculating its characteristic parameters, making it more suitable for the full-scale numerical simulation of hypervelocity impact. Moreover, this algorithm can simulate the macro breakup state of the full-scale model with complex structure and output debris fragments with clear boundaries and accurate shapes. This study provides numerical simulation method options for the follow-up research on breakup conditions, damage effects, debris clouds, and fragment characteristics of large-scale complex spacecraft.

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Zhao, HaiLong, Ke Peng, ZePing Wu, WeiHua Zhang, JiaWei Yang, and JingBo Sun. "Numerical Simulation of Supersonic Carman Curve Bodies with Aerospike." International Journal of Aerospace Engineering 2021 (April 28, 2021): 1–14. http://dx.doi.org/10.1155/2021/8821721.

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Drag reduction is one of the important problems for the supersonic vehicles. As one of the drag reduction methods, aerospike has been used in some equipment because of its good drag reduction effect. In this paper, the numerical simulations of Carman curve bodies with different lengths of the aerospike and different radius of the flat cylindrical aerodisk in supersonic flow freestream are investigated. Based on the numerical simulations, the mechanism of drag reduction of the aerospike is discussed. The drag reduction effect influence of the parameters of the aerodisk radius and the aerospike length on the Carman curve body is analyzed. The aerodisk radius within a certain range is helpful for the drag reduction. The change of length of the aerospike has little effect on the drag of Carmen curve bodies. The drag reduction effect of the same aerospike becomes worse with the increase of the incoming Mach number.

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Higgins, Ross J., Antonio Jimenez-Garcia, George N. Barakos, and Nicholas Bown. "High-Fidelity Computational Fluid Dynamics Methods for the Simulation of Propeller Stall Flutter." AIAA Journal 57, no. 12 (December 2019): 5281–92. http://dx.doi.org/10.2514/1.j058463.

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Reed, John A., and Abdollah A. Afjeh. "Computational Simulation of Gas Turbines: Part 1—Foundations of Component-Based Models." Journal of Engineering for Gas Turbines and Power 122, no. 3 (May 15, 2000): 366–76. http://dx.doi.org/10.1115/1.1287490.

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Designing and developing new aerospace propulsion systems is time-consuming and expensive. Computational simulation is a promising means for alleviating this cost, but requires a flexible software simulation system capable of integrating advanced multidisciplinary and multifidelity analysis methods, dynamically constructing arbitrary simulation models, and distributing computationally complex tasks. To address these issues, we have developed Onyx, a Java-based object-oriented domain framework for aerospace propulsion system simulation. This paper presents the design of a common engineering model formalism for use in Onyx. This approach, which is based on hierarchical decomposition and standardized interfaces, provides a flexible component-based representation for gas turbine systems, subsystems and components. It allows new models to be composed programmatically or visually to form more complex models. Onyx’s common engineering model also supports integration of a hierarchy of models which represent the system at differing levels of abstraction. Selection of a particular model is based on a number of criteria, including the level of detail needed, the objective of the simulation, the available knowledge, and given resources. The common engineering model approach is demonstrated by developing gas turbine component models which will be used to compose a gas turbine engine model in Part 2 of this paper. [S0742-4795(00)02303-6]

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Heinz, Stefan. "From Two-Equation Turbulence Models to Minimal Error Resolving Simulation Methods for Complex Turbulent Flows." Fluids 7, no. 12 (November 29, 2022): 368. http://dx.doi.org/10.3390/fluids7120368.

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Hybrid RANS-LES methods are supposed to provide major contributions to future turbulent flow simulations, in particular for reliable flow predictions under conditions where validation data are unavailable. However, existing hybrid RANS-LES methods suffer from essential problems. A solution to these problems is presented as a generalization of previously introduced continuous eddy simulation (CES) methods. These methods, obtained by relatively minor extensions of standard two-equation turbulence models, represent minimal error simulation methods. An essential observation presented here is that minimal error methods for incompressible flows can be extended to stratified and compressible flows, which opens the way to addressing relevant atmospheric science problems (mesoscale to microscale coupling) and aerospace problems (supersonic or hypersonic flow predictions). It is also reported that minimal error methods can provide valuable contributions to the design of consistent turbulence models under conditions of significant modeling uncertainties.

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Dekker, S., G. Wurzel, and R. Alderliesten. "Reliability modelling for rotorcraft component fatigue life prediction with assumed usage." Aeronautical Journal 120, no. 1232 (July 8, 2016): 1658–92. http://dx.doi.org/10.1017/aer.2016.79.

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ABSTRACTFatigue life is a random variable. Thus, the reliability of a conservative fatigue life prediction for a component in the helicopter dynamic system needs to be substantiated. A standard analytical substantiation method uses averaged manoeuvre loads instead of seeing manoeuvre loads as a random variable whose distribution is estimated with limited precision. This simplification may lead to inaccuracies. A new simulation-based method is developed to conservatively predict fatigue life, while also accounting for the full random distribution and uncertainty of manoeuvre loads. Both methods fully account for uncertain fatigue strength but assume that the mission profile is known or can at least be conservatively estimated. Simulations under synthetic but realistic engineering conditions demonstrate that both methods may be used for accurate substantiation of conservative fatigue life predictions. The simulations also demonstrate that, under the tested conditions, uncertainties from manoeuvre loads may be neglected in fatigue life substantiations as the resulting error is not significant with respect to uncertainties in component fatigue strength.

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Gong, Xiaolin, Haojie Liu, and Xing-Gang Yan. "Deformation Measuring Methods Based on Inertial Sensors for Airborne Distributed POS." International Journal of Aerospace Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/9343215.

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This paper is focused on deformation measuring methods based on inertial sensors, which are used to achieve high accuracy motion parameters and the spatial distribution optimization of multiple slave systems in the airborne distributed Position and Orientation System or other purposes. In practical application, the installation difficulty, cost, and accuracy of measuring equipment are the key factors that need to be considered synthetically. Motivated by these, deformation measuring methods based on gyros and accelerometers are proposed, respectively, and compared with the traditional method based on the inertial measurement unit (IMU). The mathematical models of these proposed methods are built, and the detailed derivations of them are given. Based on the Kalman filtering estimation, simulation and semiphysical simulation based on vehicle experiment show that the method based on gyros can obtain a similar estimation accuracy to the method based on IMU, and the method based on accelerometers has an advantage in y-axis deformation estimation.

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Rudnik, R., P. Eliasson, and J. Perraud. "Evaluation of CFD methods for transport aircraft high lift systems." Aeronautical Journal 109, no. 1092 (February 2005): 53–64. http://dx.doi.org/10.1017/s0001924000000555.

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Abstract Major results and findings of the numerical work package of the European high lift programme EUROLIFT are outlined. The main objective of these studies is to validate and test numerical methods for the prediction of high lift flows for transport aircraft configurations. The activities comprise the assessment of current CFD methods for 3D flows, evaluation of means for code improvement, and transition prediction. All aspects are especially devoted to high lift flow problems. A general capability to predict maximum lift on a simplified wing/fuselage high lift configuration is demonstrated by a variety of different numerical approaches. In general, major shortcomings are the reliability and the accurate simulation of large separation areas and the turn-around time to compute 3D lift polars. Advanced turbulence modelling and numerical solver features, such as the preconditioning technique, show a potential to overcome these deficiencies. Promising results with respect to transition prediction were obtained on a swept high lift wing using a database method. The results obtained in the numerical activities represent major ingredients on the way to a consistent numerical approach for the simulation of transport aircraft high lift configurations including all maximum lift determining effects.

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Ren, Xiang, Hua Su, Hua-Hua Yu, and Zheng Yan. "Wall-Modeled Large Eddy Simulation and Detached Eddy Simulation of Wall-Mounted Separated Flow via OpenFOAM." Aerospace 9, no. 12 (November 27, 2022): 759. http://dx.doi.org/10.3390/aerospace9120759.

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Considering grid requirements of high Reynolds flow, wall-modeled large eddy simulation (WMLES) and detached eddy simulation (DES) have become the main methods to deal with near-wall turbulence. However, the flow separation phenomenon is a challenge. Three typical separated flows, including flow over a cylinder at ReD = 3900 based on the cylinder diameter, flow over a wall-mounted hump at Rec = 9.36 × 105 based on the hump length, and transonic flow over an axisymmetric bump with shock-induced separation at Rec = 2.763 × 106 based on the bump length, are used to verify WMLES, shear stress transport k-ω DES (SST-DES), and Spalart–Allmaras DES (SA-DES) methods in OpenFOAM. The three flows are increasingly challenging, namely laminar boundary layer separation, turbulent boundary layer separation, and turbulent boundary layer separation under shock interference. The results show that WMLES, SST-DES, and SA-DES methods in OpenFOAM can easily predict the separation position and wake characteristics in the flow around the cylinder, but they rely on the grid scale and turbulent inflow to accurately simulate the latter two flows. The grid requirements of Larsson et al. (δ/Δx,δ/Δy,δ/Δz≈(12,50,20)) are the basis for simulating turbulent boundary layers upstream of flow separation. A finer mesh (δ/Δx,δ/Δy,δ/Δz≈(40,75,40)) is required to accurately predict the separation and reattachment. The WMLES method is more sensitive to grid scales than the SA-DES method and fails to obtain flow separation under a coarser grid, while SST-DES method can only describe the vortices generated by the separating shear layer, but not within the turbulent boundary layer, and overestimates the separation-reattachment zone based on the grid system in this paper.

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Pigazzini, Marco S., Yuri Bazilevs, Andrew Ellison, and Hyonny Kim. "Isogeometric analysis for simulation of progressive damage in composite laminates." Journal of Composite Materials 52, no. 25 (April 22, 2018): 3471–89. http://dx.doi.org/10.1177/0021998318770723.

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The increasing popularity of composite materials in aerospace applications is creating the need for a new class of predictive methods and tools for the simulation of progressive damage in laminated fiber-reinforced composite structures. The unique challenges associated with modeling damage in these structures may be addressed by means of thin-shell formulations which are naturally developed in the context of Isogeometric Analysis. In this paper, we further validate our recently developed Isogeometric Analysis-based multi-layer shell model for progressive damage simulations using experimental data for low-velocity impact on a 24-ply flat panel. The validation includes a careful comparison of delamination and matrix damage patterns predicted by the Isogeometric Analysis-based simulation and those obtained from post-impact non-destructive evaluation of the damaged coupon. The Isogeometric Analysis-based formulation is then deployed on two additional examples: a stiffened panel and a full-scale UAV wing, to demonstrate its suitability for, and ease of application to, typical aerospace composite structures.

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Cao, Y., and K. Chen. "Helicopter icing." Aeronautical Journal 114, no. 1152 (February 2010): 83–90. http://dx.doi.org/10.1017/s0001924000003559.

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Abstract Due to constraints of natural condition, cost and of available time associated with model fabrication and for extensive wind-tunnel tests or flight tests, Computational Fluid Dynamics (CFD) simulation was considered an alternative means of providing air vehicle icing simulation and aeromechanic performance analysis. Full-scale icing experiments and, therefore, certification and cost can be significantly reduced by developing full-numerical simulation methods to evaluate the air vehicle performance for a wide range of icing conditions. This paper summarises helicopter icing simulation methods that include the development of helicopter aerodynamics, calculation methods of helicopter icing, icing protection system performance, icing effects on the helicopter performance, and some challenges in helicopter icing simulation.

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Yue, Hui Jun, Yan Fang Liu, Gang Shi, and Xiang Yang Xu. "Free Vibration Model and Characteristics of Planetary Gear Sets." Advanced Materials Research 694-697 (May 2013): 383–88. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.383.

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Planetary gear sets have advantages of little noise, high transmission ratio, compact arrangement, so it has been widely applied in automobile and aerospace applications over the years. Using Lagrange equation, a free vibration theoretical model of a single planetary gear set was built, which was solved with modal superposition method. Combined with theoretical results, two types of modeling methods of planetary gear structures with the simulation platform SimulationX were studied. The simulation model suitable for analyzing vibration characteristic of planetary gear sets and inherent vibration characteristic in different situation were studied with the optimal modeling method. Important influencing factors of planetary gear sets vibration characteristic were studied and reference for dynamic best designing planetary gear transmission sets were provided.

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Cao, Yihua, Shuai Nie, and Zhenlong Wu. "Numerical simulation of parachute inflation: A methodological review." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 2 (May 12, 2017): 736–66. http://dx.doi.org/10.1177/0954410017705900.

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The parachute inflation process involves fluid–structure interaction problems posing several mathematical and engineering challenges, e.g. accurate aerodynamics calculations for bluff-body geometries involving with moving boundary, appropriate structural models in predicting the behavior of canopy, and realization of the coupling between the fluid and structure. These challenges attract the attention of scholars worldwide, and considerable achievements have been obtained in applying numerical methods and simulations to design multifarious parachutes. In this paper, the authors highlight the advances in the following fields: the methods suitable for time-dependent flow around bluff-body geometries, the accurate structural models in consideration of the under-constrained and no-compression nature of the canopy, and the advantages and disadvantages of different coupling algorithms in terms of numerical stability and computational economics. Moreover, in order to simulate the parachute inflation more realistically, we focus on accurate representation of three physical phenomena, as follows: an appropriate model of the flow through porous media, an accurate treatment of the wrinkling phenomenon of the canopy, and a consistent representation of the impact-contact problem associated with the inflation process. Finally, based on a review of existing literature, we offer recommendations for future research on the application of numerical methods for simulating the inflation process.

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Houshmand, Behnam, Alexander Lacher, Nikolas Juengel, Lukas Prasol, Utz von Wagner, and Eckart Uhlmann. "A novel excitation method for pyroshock simulation." Journal of Vibration and Control 22, no. 20 (August 9, 2016): 4247–58. http://dx.doi.org/10.1177/1077546315573904.

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Pyroshocks are structural responses to transient excitation caused by the essential use of pyrotechnic devices in aerospace applications. In order to avoid damage in aerospace structures due to pyroshocks, tests are performed on earth prior to launching space modules. In these tests, explosive loads are often replaced by alternative excitation methods such as hammer pendulums or shakers simulating on earth the impact taking place in space. However, there does not yet exist an adequate excitation method satisfying all requirements of a fast, reliable, predictable and repeatable test setup. Whereas hammers are poorely controllable in terms of generating desired shock spectra, shakers show limitations in terms of the bandwidths of up to 10 kHz which are prescribed in the test specifications. The authors present a novel contactless and non-destructive excitation method for pyroshock test devices based on a mechatronic coupling by applying Lorentz forces to the carrying structure. For generating the corresponding magnetic field, the capacitor of a Resistor-Inductor-Capacitor RLC resonator circuit is initially charged and then discharged leading to high currents in the coil which is placed close to the carrying structure. Latter is then inducing a counter current in the aluminum structure which reacts with high multidirectional Lorentz forces. Any adjustments are done by tuning the properties of the circuit such as initial charge, capacitance and inductance. By connecting several different coils, frequency modulation and by splitting the currents more complex signals can be generated matching the natural frequencies of the structure. Almost all disadvantages of common excitation methods are eliminated by the proposed mechanism.

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Zhuge, W., Y. Zhang, X. Zheng, M. Yang, and Y. He. "Development of an advanced turbocharger simulation method for cycle simulation of turbocharged internal combustion engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 223, no. 5 (May 1, 2009): 661–72. http://dx.doi.org/10.1243/09544070jauto975.

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An advanced turbocharger simulation method for engine cycle simulation was developed on the basis of the compressor two-zone flow model and the turbine mean-line flow model. The method can be used for turbocharger and engine integrated design without turbocharger test maps. The sensitivities of the simulation model parameters on turbocharger simulation were analysed to determine the key modelling parameters. The simulation method was validated against turbocharger test data. Results show that the methods can predict the turbocharger performance with a good accuracy, less than 5 per cent error in general for both the compressor and the turbine. In comparison with the map-based extrapolation methods commonly used in engine cycle simulation tools such as GT-POWER®, the turbocharger simulation method showed significant improvement in predictive accuracy to simulate the turbocharger performance, especially in low-flow and low-operating-speed conditions.

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Liu, Kai, Jili Zhang, and Xinlu Guo. "Reentry Flight Capability Assessment Based on Dynamics–Informed Neural Network and Piecewise Guidance." Aerospace 9, no. 12 (December 3, 2022): 790. http://dx.doi.org/10.3390/aerospace9120790.

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To improve the flexibility of the trajectory and the diversity of the drop point of the reentry vehicle, a flight capability assessment method based on a dynamics–informed neural network (DINN) is proposed. Firstly, the concept of a reachable domain is introduced to characterize the flight capability of the reentry vehicle and to estimate whether there are appropriate TAEM points in the area. Secondly, after the impact characteristic analysis, the reachable domains corresponding to different initial flight states are obtained through moderate dynamic simulations and reasonable mathematical expansion. The flight states and boundary point positions of the reachable domain are used as the training database of DINN, and the acquired DINN can realize the fast solution of reachable domains. Finally, the effectiveness of DINN in solving the reachable domain is verified using simulation. The simulation results show that DINN manifests the same accuracy as the existing solving methods and can meet the demand of determining whether the target point is located in the reachable domain. Additionally, the running time is shortened to one–800th of the existing methods, reaching the millisecond level, to support real–time assessment and decision–making. A predictor–corrector guidance algorithm with the piecewise objective function is also introduced. The simulation results illustrate that the proposed algorithm can stably guide the vehicle from the initial state points to the target points in the reachable domain.

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Stalewski, Wienczyslaw, and Katarzyna Surmacz. "Investigations of the vortex ring state on a helicopter main rotor using the URANS solver." Aircraft Engineering and Aerospace Technology 92, no. 9 (April 10, 2020): 1327–37. http://dx.doi.org/10.1108/aeat-12-2019-0264.

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Purpose This paper aims to present the novel methodology of computational simulation of a helicopter flight, developed especially to investigate the vortex ring state (VRS) – a dangerous phenomenon that may occur in helicopter vertical or steep descent. Therefore, the methodology has to enable modelling of fast manoeuvres of a helicopter such as the entrance in and safe escape from the VRS. The additional purpose of the paper is to discuss the results of conducted simulations of such manoeuvres. Design/methodology/approach The developed methodology joins several methods of computational fluid dynamics and flight dynamic. The approach consists of calculation of aerodynamic forces acting on rotorcraft, by solution of the unsteady Reynold-averaged Navier–Stokes (URANS) equations using the finite volume method. In parallel, the equations of motion of the helicopter and the fluid–structure-interaction equations are solved. To reduce computational costs, the flow effects caused by rotating blades are modelled using a simplified approach based on the virtual blade model. Findings The developed methodology of computational simulation of fast manoeuvres of a helicopter may be a valuable and reliable tool, useful when investigating the VRS. The presented results of conducted simulations of helicopter manoeuvres qualitatively comply with both the results of known experimental studies and flight tests. Research limitations/implications The continuation of the presented research will primarily include quantitative validation of the developed methodology, with respect to well-documented flight tests of real helicopters. Practical implications The VRS is a very dangerous phenomenon that usually causes a sudden decrease of rotor thrust, an increase of the descent rate, deterioration of manoeuvrability and deficit of power. Because of this, it is difficult and risky to test the VRS during the real flight tests. Therefore, the reliable computer simulations performed using the developed methodology can significantly contribute to increase helicopter flight safety. Originality/value The paper presents the innovative and original methodology for simulating fast helicopter manoeuvres, distinguished by the original approach to flight control as well as the fact that the aerodynamic forces acting on the rotorcraft are calculated during the simulation based on the solution of URANS equations.

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Vizzini, Simone, Magnus Olsson, and Alessandro Scattina. "Component mode synthesis methods for a body-in-white noise and vibration analysis." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 2 (August 5, 2016): 279–88. http://dx.doi.org/10.1177/0954407016656542.

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In this work the dynamic substructuring approach was applied to a noise, vibration and harshness problem within the automotive engineering field. In particular, a noise, vibration and harshness analysis was carried out on the body-in-white structure of a passenger car. The work focuses on the theory of component mode synthesis. Two component mode synthesis reduction methods, namely the Craig–Bampton method and the Craig–Chang method, were applied to the body-in-white structure of the Volvo V40. The influences of various parameters were investigated. In particular, the effect of the reduction basis on the response accuracy and on the reduction time was studied. Moreover, the effects of the connection properties between different parts of the model were examined. The simulation times of the reduced models and of the full finite element model were compared. The results showed that the Craig–Chang method performs better when the modes are retained for up to one and a half times the maximum frequency response studied. Additionally, the Craig–Chang method gives a very accurate representation of the system dynamics even when connections with a low stiffness are used. Finally, it is possible to reduce the simulation time by up to 90% if component mode synthesis methods are used instead of the full finite element model.

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Prochazka, F., S. Krüger, G. Stomberg, and M. Bauer. "Development of a hardware-in-the-loop demonstrator for the validation of fault-tolerant control methods for a hybrid UAV." CEAS Aeronautical Journal 12, no. 3 (May 5, 2021): 549–58. http://dx.doi.org/10.1007/s13272-021-00509-7.

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AbstractMany aircraft are inherently over-actuated with regard to their input variables. This can be particularly advantageous in the context of unmanned aerial vehicles (UAV), where actuator functions can fail in critical situations. In such cases, the redundant actuators can be used to further fulfil the control strategies used and thus increase the operational safety. Within such an active fault-tolerant control system, a fault detection and isolation (FDI) module is required. To evaluate such safety–critical systems, hardware-in-the-loop simulations (HIL) are a necessary step prior to real flight tests. These simulations can verify the correct implementation of the flight controller on the target hardware as well as the real-time capability of the algorithms used. Particularly in the context of active fault-tolerant control, investigations concerning the robustness of the used FDI module with regard to real, noisy sensor signals, which can be generated by a HIL demonstrator, are of utter importance. This paper presents the development of a HIL demonstrator for the validation of fault-tolerant control methods for a hybrid UAV. This includes a detailed description of the demonstrator’s design, control and interfacing between the integrated subsystems. As an application example, a hybrid UAV model will be shortly presented, which, in addition to the primary aerodynamic control surfaces, can also use four lift rotors to control the aircraft during cruise and is therefore inherently over-actuated. Finally, a closed-loop real-time simulation of the UAV model on the HIL demonstrator is presented on the basis of the exemplary simulation of an actuator failure and subsequent reconfiguration by the fault-tolerant flight control law.

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Baaran, J., L. Kärger, and A. Wetzel. "Efficient prediction of damage resistance and tolerance of composite aerospace structures." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 222, no. 2 (February 1, 2008): 179–88. http://dx.doi.org/10.1243/09544100jaero278.

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The present work introduces efficient methodologies based on the finite-element method for a quick evaluation of damage resistance and damage tolerance of composite aerospace structures. Monolithic, stringer-stiffened structures, and sandwich structures are considered. The presented methodologies cover the simulation of the dynamic response of a structure during a low velocity impact event including the prediction of the internal non-visible or barely visible damage that develops during the impact. Additionally, methods for the prediction of the compression-after-impact strength are presented. In order to permit an accurate and efficient calculation of deformations and stresses in sandwich structures, special finite-element formulations have been developed. A comparison of simulation results with experimental data is presented for a two-stringer monolithic panel and for a honeycomb sandwich plate. The examples demonstrate that the presented methodologies can be used to quickly assess the damage tolerance of composite structures.

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Campbell, Nicholas S., Kyle Hanquist, Andrew Morin, Jason Meyers, and Iain Boyd. "Evaluation of Computational Models for Electron Transpiration Cooling." Aerospace 8, no. 9 (September 2, 2021): 243. http://dx.doi.org/10.3390/aerospace8090243.

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Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.

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Fröhlich, Jochen, and Dominic von Terzi. "Hybrid LES/RANS methods for the simulation of turbulent flows." Progress in Aerospace Sciences 44, no. 5 (July 2008): 349–77. http://dx.doi.org/10.1016/j.paerosci.2008.05.001.

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Parkes, S. M., I. Martin, M. N. Dunstan, N. Rowell, O. Dubois-Matra, and T. Voirin. "A virtual test environment for validating spacecraft optical navigation." Aeronautical Journal 117, no. 1197 (November 2013): 1075–101. http://dx.doi.org/10.1017/s000192400000871x.

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Abstract The use of machine vision to guide robotic spacecraft is being considered for a wide range of missions, such as planetary approach and landing, asteroid and small body sampling operations and in-orbit rendezvous and docking. Numerical simulation plays an essential role in the development and testing of such systems, which in the context of vision-guidance means that realistic sequences of navigation images are required, together with knowledge of the ground-truth camera motion. Computer generated imagery (CGI) offers a variety of benefits over real images, such as availability, cost, flexibility and knowledge of the ground truth camera motion to high precision. However, standard CGI methods developed for terrestrial applications lack the realism, fidelity and performance required for engineering simulations. In this paper, we present the results of our ongoing work to develop a suitable CGI-based test environment for spacecraft vision guidance systems. We focus on the various issues involved with image simulation, including the selection of standard CGI techniques and the adaptations required for use in space applications. We also describe our approach to integration with high-fidelity end-to-end mission simulators, and summarise a variety of European Space Agency research and development projects that used our test environment.

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Katrňák, Tomáš, Jaroslav Juračka, and Ivo Jebáček. "RESEARCH OF EFFECTS OF DEFECTS ON STABILITY FAILURES OF SEMI-MONOCOQUE STIFFENERS." Aviation 23, no. 3 (January 29, 2020): 83–90. http://dx.doi.org/10.3846/aviation.2019.11903.

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This article presents further results of the research of effects of model defects on the local buckling of compressed stiffeners in nonlinear finite element (FE) analyses. The main outcomes are confirmation of trends for 10 sets of profile dimensions, final validations of various sets of FE simulations, and designs of practical types of defects with appropriate ratio values. A single node defect and then complex types of defects with alternating distributions of node shifts along one edge, two free flange edges, one flange surface and both flange surfaces are analyzed in this research project. First parts of this paper describe designed FE models with defects, their effects on simulation results, colored graphic visualizations with stress scales and determinations of the sudden failure of stability in the local mode. Then, particular results of FE analyses are validated by a comparison with the results of analytical methods of stability failure. Final detail comparisons of analytical and FE simulation results with data of experimental tests confirm predicted critical buckling forces. The validation of results and design parameters together with the knowledge of effects of model defects on buckling behaviors allows more accurate simulations of internal stiffeners of thin-walled semi-monocoque structures.

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Kuz’mina, K. S., I. K. Marchevskii, V. S. Moreva, and E. P. Ryatina. "Numerical scheme of the second order of accuracy for vortex methods for incompressible flow simulation around airfoils." Russian Aeronautics 60, no. 3 (July 2017): 398–405. http://dx.doi.org/10.3103/s1068799816030114.

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Sudo, Yasushi, and Victor W. Sparrow. "Sound propagation simulations using lattice gas methods." AIAA Journal 33, no. 9 (September 1995): 1582–89. http://dx.doi.org/10.2514/3.12696.

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Kim, Tae-Yun, Samuel Jung, and Wan-Suk Yoo. "Advanced slip ratio for ensuring numerical stability of low-speed driving simulation: Part II—lateral slip ratio." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 11 (November 14, 2018): 2903–11. http://dx.doi.org/10.1177/0954407018807040.

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A tire model is essential for vehicle dynamics simulations. The slip ratio of a tire model affects the stability of the simulation. The traditional slip ratio frequently causes numerical problems in low-speed driving simulations when the longitudinal speed approaches zero. To solve this phenomenon, many researchers have proposed various solutions by adding tuning parameters or defining the slip ratio through differential equations. However, these methods have the disadvantages of reducing the reliability of the tire model and increasing the computational complexity. In Part 1 of this paper, we proposed a method to calculate the advanced slip ratio without using tuning parameters or differential equations. This method guarantees the numerical stability of a simulation by limiting the time constant of the wheel dynamics model to be greater than the marginal time constant of the explicit integrator. In Part 1, just the longitudinal slip ratio was considered; thus, the problem of numerical instability of the slip ratio at low speed also occurs in the lateral direction. Therefore, in the second part of this study, the advanced slip ratio is extended to the lateral direction. Furthermore, the proposed method is applied to a bicycle model to verify its performance in a driving simulation. Finally, the simulation results are analyzed to verify the validity and stability of the advanced slip ratio in both directions.

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Huang, Taiming, Zhengqi Gu, Chengjie Feng, and Wei Zeng. "Transient aerodynamics simulations of a road vehicle in the crosswind condition coupled with the vehicle’s motion." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 5 (August 11, 2017): 583–98. http://dx.doi.org/10.1177/0954407017704609.

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The influence of transient aerodynamics on a vehicle in a crosswind and the effect on the vehicle’s motion are investigated by employing fully coupled simulations. The fully coupled method makes the simulation data on the fluid dynamics and on the vehicle dynamics exchange in time. LES are used to investigate the movement of the transient turbulence, and wind tunnel experiments are carried out to validate the numerical method. The vehicle is simplified as a three-degree-of-freedom system which moves in only the horizontal direction. The driver’s reaction is considered when the motion of the vehicle is simulated. The results of fully coupled simulations show that the transient aerodynamic loads have a marked influence on the motion of the vehicle. The transitional method of one-way coupled simulations is also employed to obtain data. The simulation results for the two methods are compared with each other. It is found that there is large difference between the results of the two methods. The maximum side force in fully coupled simulations is about 1.22 times the value obtained by the transitional method, and there is a 0.2 m discrepancy between the peak value of the lateral displacement in fully coupled simulations and the peak value in the transitional method. The results show that the transient aerodynamic loads induced by the unsteady motion of the vehicle have a larger effect on the vehicle’s motion than do the aerodynamic loads from the transitional method. Furthermore, the results also reflect the significance of estimating the transient aerodynamic loads in simulations of the vehicle’s motion.

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Reji, RV, and S. Anil Lal. "A new direct simulation Monte Carlo implementation for more efficient simulation of hypersonic flow over arbitrarily shaped bodies using dynamic cells." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 1 (November 13, 2016): 82–97. http://dx.doi.org/10.1177/0954410016675901.

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Methods are reported for less computationally expensive and more accurate implementations of the direct simulation Monte Carlo (DSMC) method for the simulation of high speed gas flows over arbitrarily shaped bodies. A new particle-tracking algorithm with a saving of computational time of up to 10% is reported in which tracking of particles is done with the help of big triangles having vertices lying on the boundary curves. An algorithm has been developed to generate DSMC cells for collision and sampling that contain a prescribed number of molecules. This algorithm is able to generate over 90% cells having the optimum number of seven or eight molecules for simulating collisions. Sampling for macroscopic properties is done on dynamic cells that contain a number of particles varying spatially as a function of the local number density. A criterion for finding the number of particles in sampling cells is presented. This criterion has been found to result in accurate and fast simulation of two-dimensional hypersonic flows of argon over a wedge, and argon and nitrogen over a circular cylinder.

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Journal articles on the topic 'Aerospace engineering – Simulation methods'

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