“…The choice of numerical simulation method depends on the expectation and computing resources to be spent of researchers [111,112]. In this instance, Reynolds averaged N-S equation method (RANS) can be utilized to quickly get the regular results of aerodynamic characteristics changes of bionic slotted wings under the influence of different parameters [113,114].…”
Section: Geometric Parameters In Steady Statementioning
Wingtip slots, where the outer primary feathers of birds split and spread vertically, are regarded as an evolved favorable feature that could effectively improve their aerodynamic performance. They have inspired many to perform experiments and simulations as well as to relate their results to aircraft design. This paper aims to provide guidance for the research on the aerodynamic mechanism of wingtip slots. Following a review of previous wingtip slot research, four imperfections are put forward: vacancies in research content, inconsistencies in research conclusions, limitations of early research methods, and shortage of the aerodynamic mechanism analysis. On this basis, further explorations and expansion of the influence factors for steady state are needed; more attention should be poured into the application of flow field integration method to decompose drag, and evaluation of variation in induced drag seems a more rational choice. Geometric and kinematic parameters of wingtip slot structure in the unsteady state, as well as the flexibility of wingtips, should be taken into account. As for the aerodynamic mechanism of wingtip slots, the emphasis can be placed on the study of the formation, development, and evolution of wingtip vortices on slotted wings. Besides, some research strategies and feasibility analyses are proposed for each part of the research.
“…The choice of numerical simulation method depends on the expectation and computing resources to be spent of researchers [111,112]. In this instance, Reynolds averaged N-S equation method (RANS) can be utilized to quickly get the regular results of aerodynamic characteristics changes of bionic slotted wings under the influence of different parameters [113,114].…”
Section: Geometric Parameters In Steady Statementioning
Wingtip slots, where the outer primary feathers of birds split and spread vertically, are regarded as an evolved favorable feature that could effectively improve their aerodynamic performance. They have inspired many to perform experiments and simulations as well as to relate their results to aircraft design. This paper aims to provide guidance for the research on the aerodynamic mechanism of wingtip slots. Following a review of previous wingtip slot research, four imperfections are put forward: vacancies in research content, inconsistencies in research conclusions, limitations of early research methods, and shortage of the aerodynamic mechanism analysis. On this basis, further explorations and expansion of the influence factors for steady state are needed; more attention should be poured into the application of flow field integration method to decompose drag, and evaluation of variation in induced drag seems a more rational choice. Geometric and kinematic parameters of wingtip slot structure in the unsteady state, as well as the flexibility of wingtips, should be taken into account. As for the aerodynamic mechanism of wingtip slots, the emphasis can be placed on the study of the formation, development, and evolution of wingtip vortices on slotted wings. Besides, some research strategies and feasibility analyses are proposed for each part of the research.
“…Nowadays, the existing RANS-LES hybrid methods, including DES [ 92 – 94 ], SAS [ 95 , 96 ], and PANS [ 97 , 98 ], etc., are constructed by recovering the RANS methods in the boundary layer and using the LES elsewhere. Therefore, it is in a high demand to analyze the low-speed turbulent flow’s accuracy using RANS methods, and Refs [ 99 , 100 ] conducted studies on this issue with several test cases.…”
Section: Importance Of the All-speed Riemann Solver For Hypersonic Flowsmentioning
confidence: 99%
“… Fig. 19 Comparisons of schemes’ surface pressure distributions (Turbulent flow past a NACA0012 airfoil case, grid resolution 449 × 129) [ 99 ] Fig. 20 Comparison of schemes’ surface pressure distributions (Turbulent flow past a NACA0012 airfoil case, grid of 897 × 257) [ 99 ] …”
Section: Importance Of the All-speed Riemann Solver For Hypersonic Flowsmentioning
confidence: 99%
“… Comparisons of schemes’ surface pressure distributions (Turbulent flow past a NACA0012 airfoil case, grid resolution 449 × 129) [ 99 ] …”
Section: Importance Of the All-speed Riemann Solver For Hypersonic Flowsmentioning
In the design of the hypersonic airliner which can greatly shorten the flight time and conduct space travel, it is of great significance for a Riemann solver to accurately simulate hypersonic flows. In this survey, the research process on the Riemann solver for hypersonic flows is reviewed, including the constructions of the traditional Riemann solvers, improvements of the traditional Riemann solvers for the shock anomaly, and the importance of the all-speed Riemann solver for hypersonic flows. Moreover, constructions and applications of the all-speed Riemann solvers are presented. It is obvious that the Riemann solver should be capable of obtaining physical solutions at low speeds and be robust against shock anomaly near strong shocks at the same time in simulating hypersonic flows.
“…Additionally, these exhibit low local values of the Reynolds and Mach numbers. The accuracy of low-Mach flow simulations is directly affected by the ability of compressible solvers to reproduce flows in the incompressible limit [9].…”
Improved wall boundary treatments are investigated for a family of high-order Godunovtype finite volume schemes based on k-exact polynomial reconstructions in each cell of the primitive variables, via a successive corrections procedure. We focus more particularly on the 1-exact and 2-exact schemes which offer a good trade-off between accuracy and computational efficiency. In both cases, the reconstruction stencil needs to be extended to the boundaries. Additionally, information about wall curvature has to be taken into account, which is done by using a surface model based on bicubic Bézier patches for the walls. The performance of the proposed models is presented for two compressible cases, namely the inviscid flow past a Gaussian bump and the viscous axisymmetric Couette flow.
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