## Person: Pinelli, Alfredo

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##### First Name

Alfredo

##### Last Name

Pinelli

##### Affiliation

Universidad Complutense de Madrid

##### Faculty / Institute

Ciencias Matemáticas

##### Department

##### Area

Matemática Aplicada

##### Identifiers

3 results

## Search Results

Now showing 1 - 3 of 3

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 Chebyshev pseudospectral solution of advection-diffusion equations with mapped finite difference preconditioning(Elsevier, 1994) Pinelli, Alfredo; Benocci, C.; Deville, M.A new Chebyshev pseudo-spectral algorithm with finite difference preconditioning is proposed for the solution of advection-diffusion equations, A mapping technique is introduced which allows good convergence for any Peclet number both for one-dimensional and two-dimensional problems. Numerical results show that first-order Lagrange polynomials are the optimal mapping procedure for the one-dimensional problem and second-order Lagrange polynomials, for the two-dimensional one.Publication Immersed-boundary methods for general finite-difference and finite-volume Navier-Stokes solvers(Elsevier, 2010) Pinelli, Alfredo; Naqavi, I.Z.; Piomelli, U.; Favier, J.We present an immersed-boundary algorithm for incompressible flows with complex boundaries, suitable for Cartesian or curvilinear grid system. The key stages of any immersed-boundary technique are the interpolation of a velocity field given on a mesh onto a general boundary (a line in 2D, a surface in 3D), and the spreading of a force field from the immersed boundary to the neighboring mesh points, to enforce the desired boundary conditions on the immersed-boundary points. We propose a technique that uses the Reproducing Kernel Particle Method [W.K. Liu, S. Jun, Y.F. Zhang, Reproducing kernel particle methods, Int. J. Numer. Methods Fluids 20(8) (1995) 1081-1106] for the interpolation and spreading. Unlike other methods presented in the literature, the one proposed here has the property that the integrals of the force field and of its moment on the grid are conserved, independent of the grid topology (uniform or non-uniform, Cartesian or curvilinear). The technique is easy to implement, and is able to maintain the order of the original underlying spatial discretization. Applications to two- and three-dimensional flows in Cartesian and non-Cartesian grid system, with uniform and non-uniform meshes are presented.