ESTIMASI TEGANGAN GESER DASAR UNTUK GELOMBANG IRREGULER

The bottom shear stress of the turbulent bottom boundary layer under irregular wave over rough bed has been examined through two methods. The first is to fit logarithmic velocity profile to the measured velocity in an oscillating wind tunnel, and the second is a calculation method based on a quadratic of free stream velocity. However, an investigation of a more reliable calculation method to estimate the time- variation of bottom shear stress has not been fully dealt with. In the present study, the new method for calculating the instantaneous bottom shear stress under irregular waves proposed. The bottom shear stress of experimental result will be examined with both calculation method of bottom shear stress –based on incorporating velocity and acceleration terms all at once- and existing calculation methods. The calculation method gives a good agreement with the bottom shear stress under irregular waves from experimental results. Therefore this method can be used to an input sediment transport model under rapid acceleration in a practical application.