MIXING BY SHEAR INSTABILITIES OF THE LONGSHORE CURRENT

J.C. Church, E.B. Thornton, J. Oltman-Shay

Abstract


Shear instabilities of the longshore current are examined as a possible source of non-zero uV values (mixing) within the surfzone. This term is calculated using model generated stream functions whose amplitudes are calibrated with the observed turbulent kinetic energy spectrum. Data from the DELILAH experiment, conducted at the barred beach at Duck, North Carolina is used. Excellent agreement is found between the predicted range of shear instabilities and observations as seen in frequency-wavenumber plots. Maximum predicted values for u'2, v-'2 and WP are .04, .20, and .03 mVs2.

Keywords


longshore current; mixing; shear instability

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