For the known spectral methods (Galerkin, Tau, Collocation) the condition number behaves like 0(N4) (N: maximal degree of polynomials). We introduce a spectral method with an 0(N2) condition number. The advantages with respect to propagation of rounding errors and preconditioning are demonstrated. A direct solver for constant coefficient problems is given. Extensions to variable coefficient pro...

We prove that a popular classical implicit-explicit scheme for the 2D incompressible Navier–Stokes equations that treats the viscous term implicitly while the nonlinear advection term explicitly is long time stable provided that the time step is sufficiently small in the case with periodic boundary conditions. The long time stability in the L2 and H1 norms further leads to the convergence of th...

Numerical approximations of fractional PDEs in unbounded domains are considered in this paper. Since their solutions decay slowly with power laws at infinity, a domain truncation approach is not effective as no transparent boundary condition is available. We develop efficient Hermite-collocation and Hermite–Galerkin methods for solving a class of fractional PDEs in unbounded domains directly, a...

In many calculations, spectral discretization in space is coupled with a standard ordinary differential equation formula in time. To analyze the stability of such a combination, one would like simply to test whether the eigenvalues of the spatial discretization operator (appropriately scaled by the time step k) lie in the stability region for the o.d.e. formula, but it is well known that this k...

Nonlinear entropy stability and a summation-by-parts framework are used to derive provably stable, polynomial-based spectral collocation methods of arbitrary order. The new methods are closely related to discontinuous Galerkin spectral collocation methods commonly known as DGFEM, but exhibit a more general entropy stability property. Although the new schemes are applicable to a broad class of l...

and Applied Analysis 3 nonlinear term is treated with the Chebyshev collocation method. The time discretization is a classical Crank-Nicholson-leap-frog scheme. Yuan and Wu 43 extended the Legendre dual-Petrov-Galerkin method proposed by Shen 44 , further developed by Yuan et al. 45 to general fifth-order KdV-type equations with various nonlinear terms. The main aim of this paper is to propose ...

respect to Jacobi polynomials. Using this approach is efficient and effective rather than Tau and collocation methods. It reduces the nonlinear ordinary differential equations to the nonlinear programming problems which is an easy problem to solve. Hence, easy implementation of the method is the importance of our approach and some numerical test experiments show the accuracy and efficiency of t...

The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. Our approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral...

We illustrate in the present paper how steady-state and unsteady-steady three-dimensional transport phenomena problems can be solved using the Chebyshev orthogonal collocation technique. All problems are elucidated using the ubiquitous software: MATLAB 1 . The treated case studies include: (1) unsteadystate heat conduction in a parallelepiped body, (2) quenching of a brick, (3) transient diffus...

We present a new method for separating ground deformation from atmospheric phase screen (APS) based on PSInSAR. By stochastic modeling of ground deformation and APS via their variance-covariance functions we can not only estimate the signals with the best accuracy but also assess the estimation accuracy using least-squares collocation [5]. We evaluate the APS estimated by our method and the APS...