Fig. 1

The piston radiator. a On-axis and on-edge intensities. b Contributions to the streaming velocities in the calculational method. As the text indicates, we use the average of the on-axis and on-edge intensities displayed in (a). Our calculation uses the reflecting Green function which is a sum of two terms shown in (b) as “direct” and “image” sources. The contribution of the streaming force and finally that of the harmonic function needed to cancel out streaming on the plane of the radiator are also shown. The total streaming velocity is a sum of all these and is dominated by the direct Green function a little bit away from the radiator