Seiches in a butterfly-shaped basin

Abstract

Long barotropic seiches are investigated in a basin of constant depth bounded by curves of an eliptical-hyperbolic coordinate system. Both plnnetnry and gravitational seiches are evalunted numerically by an iteration procedure. It is found that the frequencies of the gravitational seiches decrease with decreasing width of the narrow waist of tlte basin, in acordance with tlte theory of the Helmholz resonator, and the strongest currents are found in the waist of the basin. For planetary seiches, tite frequencies generally increase with decreasing width of the waist, tho not dramatically, and the associa·ted currents are weakest in the narrow waist.