Evaluation of an eddy viscosity type wave breaking model for intermediate water depths

Abstract

Abstract This paper examines the results in case of breaking wave groups reported in Sriram et al. (2015) against a wave breaking model called Tian–Barthelemy model (Seiffert and Ducrozet, 2017). In this paper, Tian–Barthelemy model is extended to incorporate (Schaffer, 1996) corrections to linear wave making signals for generating focused wave groups and implemented in an open source computer code for high order spectral (HOS) method based numerical wave tank (NWT) viz., HOS-NWT. The developed model is then studied in the context of wave breaking in dispersively focused intermediate water wave groups with particular focus on multiple wave breaking events. The adapted model performs well in conformity with experimental observations in Sriram et al. (2015). A range of kinematic thresholds are studied with this model to calibrate the right threshold for the model against the experiments. We find strong evidence of a non-breaking wave group in intermediate depths crossing the kinematic threshold of 0.85 (stated in Seiffert and Ducrozet (2017)), implying that this threshold is not universal for intermediate depths. It is also shown that the model does not interfere with the spurious free wave suppression. However, various dynamic and kinematical aspects of this study reveal that suppression of spurious free wave makes the short waves dominant in the lead up to breaking. Hence, the model detects numerous threshold exceedences implying plausibly more wave breaking instances. It is also shown that this model in general violates the spectral signature of breaking in a dispersively focused wave.