  The paper presents first a linear stability analysis for the time-parallel
Parareal method, using an IMEX Euler as coarse and a Runge-Kutta-3 method as
fine propagator, confirming that dominant imaginary eigenvalues negatively
affect Parareal's convergence. This suggests that when Parareal is applied to
the nonlinear Navier-Stokes equations, problems for small viscosities could
arise. Numerical results for a driven cavity benchmark are presented,
confirming that Parareal's convergence can indeed deteriorate as viscosity
decreases and the flow becomes increasingly dominated by convection. The effect
is found to strongly depend on the spatial resolution.
