A wave energy-dominated Cochin harbour inlet is selected to extract wave radiation stress due to wave transformation. In complex coastal environments, such as tidal inlets, wave transformations are not accurately captured by the phase-averaged models. So, the captured wave spectrum from the time domain phase-averaged model TOMAWAC is applied as a boundary to the frequency domain phase-resolving model ARTEMIS. The time series of wave parameters from ARTEMIS are constructed using the random phase method. The outputs from both models are integrated into the hydrodynamic mesh, and wave radiation stresses are calculated analytically for hydrodynamic studies.
Inlets are complex coastal features where both tides and waves significantly influence their morphological behaviour (Hayes, 1980). There are three types of tidal inlets: wave-dominated, tidal-dominated, and transitional (Hubbard, Oertel, and Nummedal, 1979). Wave-dominated inlets exhibit intricate morphodynamic changes during the monsoon and non-monsoon periods, particularly in countries like India (Vikas, 2015). Understanding the complex morphological behaviours of these tidal inlets necessitates numerical modeling to capture the intricate physical processes involved (Tung, Walstra, and van de Graff, 2009). Such modeling requires an integrated approach, combining hydrodynamic, wave, and sediment transport models to accurately predict sediment transport driven by wave-induced and tide-induced currents (Vriend, Zyserman, Nicholson, Roelvink, Pechon, and Southgate, 1993).
Tide-induced currents are obtained from the hydrodynamic models, which solve 2D shallow water equations (Murali, Lou, and Kumar,2002). Wave-induced currents can be extracted from the phase-averaged or phase-resolved models as radiation stresses (Newell, Mullarkey, and Clyne, 2005). The phrase ‘Radiation stress’ was initially used by Longuet-Higgins and Stewart (1963) to explain the phenomenon of wave setup. Radiation stress is an excess flow of momentum due to the presence of waves and is used to compute wave-induced flow (Longuet-Higgins and Stewart, 1964). According to Battjes (1972), radiation stress is the contribution of the waves to the time average of the vertically integrated horizontal flow of horizontal momentum. The stress term analogous to turbulence stress arises from wave momentum flux due to the averaging over the wave scales of the advective accelerations (Whitham,1965), (Williebrand,1975). As the radiation stress concept evolved and was applied to 2D depth-integrated circulation models, nearshore wave and current dynamics emerged (Cobb and Blain,2001).