Fekete-Gauss spectral elements for incompressible Navier-Stokes flows: The two-dimensional case
Résumé
Spectral element methods on simplicial meshes, say TSEM, show both the
advantages of spectral and finite element methods, i.e., spectral accuracy and geometrical
flexibility. We present a TSEM solver of the two-dimensional (2D) incompressible
Navier-Stokes equations, with possible extension to the 3D case. It uses a projection
method in time and piecewise polynomial basis functions of arbitrary degree in space.
The so-called Fekete-Gauss TSEM is employed, i.e., Fekete (resp. Gauss) points of the
triangle are used as interpolation (resp. quadrature) points. For the sake of consistency,
isoparametric elements are used to approximate curved geometries. The resolution algorithm
is based on an efficient Schur complement method, so that one only solves
for the element boundary nodes. Moreover, the algebraic system is never assembled,
therefore the number of degrees of freedom is not limiting. An accuracy study is carried
out and results are provided for classical benchmarks: the driven cavity flow, the
flow between eccentric cylinders and the flow past a cylinder.