  We present a reduced basis approach to solve the convected Helmholtz equation
with several physical parameters. Physical parameters characterize the
aeroacoustic wave propagation in terms of the wave and Mach numbers. We compute
solutions for various combinations of parameters and spend a lot of time to
figure out the desired set of parameters. The reduced basis method saves the
computational effort by using the Galerkin projection, a posteriori error
estimator, and greedy algorithm. Here, we propose an efficient a posteriori
error estimator based on the primal norm. Numerical experiments demonstrate the
good performance and effectivity of the proposed error estimator.
