Transport of energy across a discontinuity by fluid loading

Short-circuiting effects due to fluid loading have been investigated for a plane flexural wave obliquely incident upon a line discontinuity in an elastic plate. General expressions for the transmission and reflection coefficients have been derived and exact analytical formulas are given for the required Green’s functions. The transmission coefficient resulting from the fluid loading has been evaluated and found to have a strong, step-function-like angular dependence vanishing at large angles of incidence. In addition, the near-field pressure and velocity fields have been numerically computed to directly examine the energetics of the transmission process. Transmission due to the fluid has been found to arise from propagating acoustic fields that must carry energy a distance of the order of a flexural wavelength. Accordingly, for angles greater than the critical angle, sin θc=k0/ks, transmission due to the fluid is strongly suppressed due to phase cancellation along the line discontinuity, thus explaining the angular dependence of the transmission coefficient.