Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Friday, October 18, 2013 - 05:00 to 06:00
GLK 115

Speaker Info

OSU CEOAS and Engineering

Models for surface gravity wave propagation in the presence of currents
often assume the current field to be quasi-stationary, which implies that the absolute wave frequency is time invariant. However, in the presence of unsteady currents or time-varying water depth, linear wave theory predicts a time variation of the absolute wave frequency ^Aand wavenumber. Herein, observations of wave frequency modulations from a large-scale laboratory experiment are presented. In this case, the modulations are caused by both unsteady depths and unsteady currents due to the presence of
low-frequency standing waves. These new observations allow a unique and
detailed verification of the theoretical predictions regarding variations in the absolute wave frequency. In addition, analytic solutions for the variations in frequency and wave height induced by the unsteady medium are found through a perturbation analysis. These solutions clarify the dependency of the wave frequency/wave height modulations on the characteristics of the unsteady medium. We also find that analytic
solutions for simplified basin configurations provide an order of magnitude estimate of the expected frequency modulation effect. Finally, the importance of this phenomenon in natural situations is discussed.

Also see our paper on the subject at