Pinelli, Alfredo

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Universidad Complutense de Madrid
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Ciencias Matemáticas
Matemática Aplicada
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Now showing 1 - 3 of 3
  • Publication
    An efficient iterative solution method for the Chebyshev collocation of advection-dominated transport problems
    (Society for Industrial and Applied Mathematics, 1996) Pinelli, Alfredo; Couzy, W.; Deville, M. O.; Benocci, C.
    A new Chebyshev collocation algorithm is proposed for the iterative solution of advection-diffusion problems. The main features of the method lie in the original way in which a finite-difference preconditioner is built and in the fact that the solution is collocated on a set of nodes matching the standard Gauss-Lobatto-Chebyshev set only in the case of pure diffusion problems. The key point of the algorithm is the capability of the preconditioner to represent the high-frequency modes when dealing with advection-dominated problems. The basic idea is developed for a one-dimensional case and is extended to two-dimensional problems. A series of numerical experiments is carried out to demonstrate the efficiency of the algorithm. The proposed algorithm can also be used in the context of the incompressible Navier-Stokes equations.
  • Publication
    A spectral multidomain method for the numerical simulation of turbulent flows
    (Elsevier, 1997) Pinelli, Alfredo; Vacca, A.; Quarteroni, A.
    The primitive variable formulation of the unsteady incompressible Navier-Stokes equations in three space dimensions is discretized with a combined Fourier-Legendre spectral method. A semi-implicit pressure correction scheme is applied to decouple the velocity from the pressure. The arising elliptic scaler problems are first diagonalized in the periodic Fourier direction and then solved by a multidomain Legendre collocation method in the two remaining space coordinates. In particular, both an iterative and a direct version of the so-called projection decomposition method (PDM) are introduced to separate the equations for the internal nodes from the ones governing the interface unknowns. The PDM method, first introduced by V. Agoshkov and E. Ovtchinnikov and later applied to spectral methods by P. Gervasio, E. Ovtchinnikov, and A. Quarteroni is a domain decomposition technique for elliptic boundary value problems, which is based on a Galerkin approximation of the Steklov-Poincare equation for the unknown variables associated to the grid points lying on the interface between subdomains. After having shown the exponential convergence of the proposed discretization technique, some issues on the efficient implementation of the method are given. Finally, as an illustration of the potentialities of the algorithm for the numerical simulation of turbulent flows, the results of a direct numerical simulation (DNS) of a fully turbulent plane channel flow are presented.
  • Publication
    The instability of streaks in near-wall turbulence
    (Center for Turbulence Research, 1998) Kawahara, Genta; Jiménez, Javier; Uhlmann, Markus; Pinelli, Alfredo