Navier-Stokes solver using Green's functions II: spectral integration of channel flow and plane Couette flow

The Kleiser-Schumann algorithm has been widely used for the direct numerical simulation of turbulence in rectangular geometries. At the heart of the algorithm is the solution of linear systems which are tridiagonal except for one row. This note shows how to solve the Kleiser-Schumann problem using perfectly triangular matrices. An advantage is the ability to use functions in the LAPACK library. The method is used to simulate turbulence in channel flow at $Re=80,000$ (and $R{e}_{\tau }=2400$) using ${10}^9$ grid points. An assessment of the length of time necessary to eliminate transient effects in the initial state is included.