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Dataset: for On the Sensitivity and Efficiency of Aerodynamic Shape Optimisation
No full textThis dataset supports the thesis entitled 'On the Sensitivity and Efficiency of Aerodynamic Shape Optimisation'.
This dataset contains the data associated with the results in the thesis to generate the figures and plots.
- Chap4_NACA: data for aerodynamic optimisation of the two-dimensional NACA0012 aerofoil;
- Chap5_RAE: data for aerodynamic optimisation of the two-dimensional RAE2822 aerofoil;
- Chap6_WTO: data for twist optimisation of the three-dimensional wings;
- Appendix: data for CFD validation of the SU2 solver.
The Tecplot software is required to view the data which are mostly in the 'xxx.dat' and 'xxx.lpk' format.</span
On the sensitivity and efficiency of aerodynamic shape optimisation
No full textComputational fluid dynamics (CFD) has become the method of choice for aerodynamic shape optimisation of complex engineering problems. To date, however, the sensitivity of the optimal solution to numerical parameters has been largely underestimated. Meanwhile, aerodynamic shape optimisation based on high-fidelity CFD remains a computationally expensive task. The thesis consists of two research streams aimed at addressing each of the challenges identified, namely revisiting the optimal solution and developing an efficient optimisation framework. This work primarily focuses on the assessment of optimal design sensitivity and computational efficiency in gradient-based optimisation of aeronautical applications.Two benchmark cases for NACA0012 and RAE2822 aerofoil optimisation are investigated using the open-source SU2 code. Hicks-Henne bump functions and free-form deformation are employed as geometry parameterisation methods. Gradients are computed by the continuous adjoint approach. The optimisation results of NACA0012 aerofoil exhibit strong dependence on virtually all numerical parameters investigated, whereas the optimal design of RAE2822 aerofoil is insensitive to those parameter settings. The degree of sensitivity reflects the difference in the design space, particularly of the local curvature on the optimised shape. The closure coefficients of Spalart-Allmaras model affect the final optimisation performance, raising the importance of quantifying uncertainty in turbulence modelling calibration. Non-unique flow solutions are found to exist for both cases, and hysteresis occurs in a narrow region near the design point.Wing twist optimisations are conducted using two aerodynamic solvers of different levels of fidelity. A multi-fidelity aerodynamic approach is proposed, which contains three components: a linear vortex lattice method solver, an infinite swept wing solver, and a coupling algorithm. For reference, three-dimensional data are obtained using SU2. Two optimisation cases are considered, featuring inviscid flow around an unswept wing and viscous flow around a swept wing. A good agreement in terms of lift distribution and aerodynamic shape between the multi-fidelity solver and high-fidelity CFD is obtained. The numerical optimisation using the multi-fidelity approach is performed at a negligible computational cost compared to the full three-dimensional CFD solver, demonstrating the potential for use in early phases of aircraft design
Aerodynamic shape optimisation of benchmark problems using SU2
No full textIn this paper, results are presented from the application of an open–source code, SU2, to a suite of benchmark cases defined by the AIAA Aerodynamic Design Optimisation Discussion Group. Two geometry parameterisation methods are employed, which are Hicks– Henne bump functions and Free–Form Deformation. Mesh deformation is achieved by solving linear elasticity equations. The adjoint solver within SU2 enables efficient sensitivity analysis, and gradient–based optimisation is performed using the SLSQP optimiser. The first optimisation problem studied is the drag minimisation of the NACA 0012 aerofoil in inviscid, transonic flow subject to a minimum thickness constraint. The shock wave is greatly weakened and moved downstream, achieving as much as 83% drag reduction. The second is the lift–constrained drag minimisation of the RAE 2822 aerofoil in transonic, viscous flow. The shock is eliminated, reducing drag by 38%. The NACA 0012 optimisation shows sensitivity to several numerical settings in the parameterisation approaches, whereas the RAE 2822 optimisation is insensitive to those parameter settings. The same pattern is also observed in the design variable dimensionality study. Moreover, for both two–dimensional optimisation problems, non–unique flow solutions exist on the optimised aerofoil. The third problem is the twist optimisation of a rectangular wing to minimise the induced drag at fixed lift in subsonic, inviscid flow. A nearly elliptical lift distribution is obtained using Free–Form Deformation twist parameterisation. The drag is reduced by approximately 1 count and an improved span efficiency is achieved.</p
Sensitivity assessment of optimal solution in aerodynamic design optimisation using SU2
No full textComputational fluid dynamics has become the method of choice for aerodynamic shape optimisation of complex engineering problems. However, the sensitivity of the final aerodynamic shape to numerical parameters has been largely underestimated to date. The purpose of this work is to investigate the influence that numerical parameters have on the optimisation results for two aerofoil problems (NACA 0012 and RAE 2822) in transonic flow, and to provide compact guidelines for best practice. Numerical parameters include: a) two parameterisation methods, Hicks-Henne bump functions and free{form deformation; b) numerical settings related to the tuning of each parameterisation method; and c) closure coefficients of Spalart-Allmaras (SA) turbulence model. All optimisations were performed using the open{source software tool SU2, and gradients were computed using the continuous adjoint method. It was found that: a) the optimisation result of NACA 0012 aerofoil exhibits strong dependence onall numerical parameters investigated, whereas the optimal design of RAE 2822 aerofoil is insensitive to those numerical settings; b) the degree of sensitivity reflects the difference in the design space, particularly of the local curvature on the optimised shape; c) the closure coefficients of SA model affect the final optimisation performance, raising the need for a good calibration of the turbulence model
Dataset for Sensitivity Assessment of Optimal Solution in Aerodynamic Design Optimisation using SU2
No full textThe database contains data in support of the manuscript 'Sensitivity Assessment of Optimal Solution in Aerodynamic Design Optimisation using SU2' (https://doi.org/10.1016/j.ast.2018.08.012). In particular, grid files and solution files that were used for the generation of the figures are made available. Each subfolder contains a README.dat file.</span
Wing twist optimisation using aerodynamic solvers of different fidelity
No full textComputational fluid dynamics has become the method of choice for aerodynamic shape optimisation. However, the computational cost poses challenges for the routine use of high-fidelity flow solvers in the early phase of aircraft design. In this paper, a benchmark wing twist optimisation problem is investigated using two aerodynamic solvers of different fidelity. The first solver is the open-source SU2 software, and the second is an efficient hybrid solver which couples a linear vortex lattice method with an infinite-swept wing solver. Numerical details of two optimisation frameworks are presented. It is demonstrated that the hybrid solver can accurately reproduce the aerodynamic loads on the three-dimensional wing. Optimisation results show that both optimisations can effectively minimise the induced drag by recovering a nearly elliptical lift distribution. In comparison to SU2 optimisation, the hybrid approach achieves a speed-up of two orders of magnitude
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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