Archivo Digital UPM: No conditions. Results ordered -Date Deposited. 2019-07-23T06:23:38ZEPrintshttp://oa.upm.es/style/images/logo-archivo-digital.pnghttp://oa.upm.es/2015-04-21T10:24:37Z2015-04-21T10:24:37Zhttp://oa.upm.es/id/eprint/15415This item is in the repository with the URL: http://oa.upm.es/id/eprint/154152015-04-21T10:24:37ZReduced order modeling of three dimensional external aerodynamic flowsA method is presented to construct computationally efficient reduced-order models (ROMs) of three-dimensional aerodynamic flows around commercial aircraft components. The method is based on the proper orthogonal decomposition (POD) of a set of steady snapshots, which are calculated using an industrial solver based on some Reynolds averaged Navier-Stokes (RANS) equations. The POD-mode amplitudes are calculated by minimizing a residual defined from the Euler equations, even though the snapshots themselves are calculated from viscous equations. This makes the ROM independent of the peculiarities of the solver used to calculate the snapshots. Also, both the POD modes and the residual are calculated using points in the computational mesh that are concentrated in a close vicinity of the aircraft, which constitute a much smaller number than the total number of mesh points. Despite these simplifications, the method provides quite good approximations of the flow variables distributions in the whole computational domain, including the boundary layer attached to the aircraft surface and the wake. Thus, the method is both robust and computationally efficient, which is checked considering the aerodynamic flow around a horizontal tail plane, in the transonic range 0.4?Mach number?0.8, ?3°?angle of attack?3°.Jose Manuel Vega De PradaD. AlonsoAngel VelázquezValentín de Pablo2011-02-24T09:22:41Z2016-04-20T15:27:36Zhttp://oa.upm.es/id/eprint/6150This item is in the repository with the URL: http://oa.upm.es/id/eprint/61502011-02-24T09:22:41ZApplication of HOSVD to Aerodynamics. The Problem of Shock WavesEfficient interpolation in aerodynamic databases is important for the aeronautic industry because of its implication on both the cost and time needed to complete design cycles. In this study a method based on high-order singular value decomposition is presented focusing on the problems associated with the shock wave like structures that do not suit well with this kind of methods. To illustrate the methodology, the flow around a two-dimensional airfoil is considered at a Reynolds number of 20 × 106 with three free parameters, namely, the Mach number, the angle of attack, and the flap deflection angle in the ranges of [0.4, 0.8], [¿3º, 3º], and [¿5º, 5º], respectively. The method is robust in the sense of being able to deal with very different flow topologies.L. S. LorenteD. AlonsoJosé Manuel Vega de PradaA. Velázquez2011-02-21T10:30:15Z2016-04-20T14:44:19Zhttp://oa.upm.es/id/eprint/6106This item is in the repository with the URL: http://oa.upm.es/id/eprint/61062011-02-21T10:30:15ZA method to generate computationally efficient reduced order modelsA new method is presented to generate reduced order models (ROMs) in Fluid Dynamics problems. The method is based on the expansion of the flow variables on a Proper Orthogonal Decomposition (POD) basis, calculated from a limited number of snapshots, which are obtained via Computational Fluid Dynamics (CFD). Then, the POD-mode amplitudes are calculated as minimizers of a properly defined overall residual of the equations and boundary conditions. The residual can be calculated using only a limited number of points in the flow field, which can be scattered either all over the whole computational domain or over a smaller projection window. This means that the process is both computationally efficient (reconstructed flow fields require less than 1% of the time needed to compute a full CFD solution) and flexible (the projection window can avoid regions of large localized CFD errors). Also, various definitions of the residual are briefly discussed, along with the number and distribution of snapshots, the number of retained modes, and the effect of CFD errors, to conclude that the method is numerically robust. This is because the results are largely insensitive to the definition of the residual, to CFD errors, and to the CFD method itself, which may contain artificial stabilizing terms. Thus, the method is amenable for practical engineering applications.D. AlonsoA. VelázquezJosé Manuel Vega de Prada2011-01-12T09:51:11Z2016-04-20T14:26:37Zhttp://oa.upm.es/id/eprint/5703This item is in the repository with the URL: http://oa.upm.es/id/eprint/57032011-01-12T09:51:11ZAsymptotic Resource Usage BoundsWhen describing the resource usage of a program, it is usual to talk in asymptotic terms, such as the well-known “big O” notation, whereby we focus on the behaviour of the program for large input data and make a rough approximation by considering as equivalent programs whose resource usage grows at the same rate. Motivated by the existence of non-asymptotic resource usage analyzers, in this paper, we develop a novel transformation from a non-asymptotic cost function (which can be produced by multiple resource analyzers) into its asymptotic form. Our transformation aims at producing tight asymptotic forms which do not contain redundant subexpressions (i.e., expressions asymptotically subsumed by others). Interestingly, we integrate our transformation at the heart of a cost analyzer to generate asymptotic upper bounds without having to ﬁrst compute their non-asymptotic counterparts. Our experimental results show that, while non-asymptotic cost functions become very complex, their asymptotic forms are much more compact and manageable. This is essential to improve scalability and to enable the application of cost analysis in resource-aware veriﬁcation/certiﬁcation.Elvira Albert AlbiolD. AlonsoPurificación Arenas SánchezSamir GenaimAlvaro Germán Puebla Sánchez