Tidal generation of internal waves from a periodic array of steep ridges

The generation of internal gravity waves by an oscillatory tidal flow over a periodic array of thin vertical walls is calculated analytically. For small values of the non-dimensional height B = 27 pi HN/L omega, the radiated power per wall is the same as for a single thin wall, and proportional to B-2, in agreement with the linear scaling. (Here H is the wall height, N the buoyancy frequency, L the wall spacing, and N the tidal frequency.) The radiated power is periodic in B with period 2 pi. It diverges logarithmically for B = (1 + 2n)pi, and vanishes for B = 2n pi.