Numerical modelling of wind-modified focused waves in a numerical wave tank

In this paper, we extend the non-breaking second-order corrected focused wave experimental results of Sriram et al. (2015) in a numerical wave tank based on HOS in the presence of wind. The wind is modelled using the modified Jeffrey's Sheltering Mechanism (Kharif et al., 2008). We take care to preserve the consistency of application of pressure terms in the hybrid Stokesian-HOS formulations when applying wind. We confirm the results of Kharif et al. (2008) i.e. the focusing points in presence of wind show an amplification of the measure wave heights although no discernible shifting of focusing location is observed. However, compared to Kharif et al. (2008), the sheltering mechanism is found to be very weak since it depends on exceedance of a threshold slope based on constant steepness or constant amplitude spectrum. The energy flux to local phase celerity (Bx) both in absence and presence of the aforementioned wind model for the detection of onset of wave breaking (Barthelemy et al., 2015b; Saket et al., 2017b) are reported. Moreover, in the absence of wind, if Bx is used as parameter the onset of wave breaking, then for intermediate water wave groups its threshold should be close to 0.9 (computations based on Kurnia and van Groesen (2014)).