@article{fdi:010082094,
  title = {{T}ridimensional nonhydrostatic transient rip currents in a wave-resolving model},
  author = {{M}archesiello, {P}atrick and {A}uclair, {F}. and {D}ebreu, {L}. and {M}c{W}illiams, {J}. and {A}lmar, {R}afa{\¨e}l and {B}enshila, {R}. and {D}umas, {F}.},
  editor = {},
  language = {{ENG}},
  abstract = {{F}lash rips and surf eddies are transient horizontal structures of the order of 10 to 100 m, which can be generated in the surfzone in the absence of bathymetric irregularities. {T}hey are traditionally evaluated in a depth averaged setting which involves intrinsic horizontal shear instabilities and the direct generation of vorticity by short-crested waves. {I}n this article, we revisit the processes of surf eddy generation with a new three-dimensional wave resolution model ({CROCO}) and provide a plausible demonstration of new 3{D} non hydrostatic instability and turbulent cascade. {W}e first present a quick overview of a compressible free surface approach suitable for nearshore dynamics. {I}ts ability to simulate the propagation of surface gravity waves and nearshore wave-driven circulation is validated by two laboratory experiments. {N}ext, we present a real world application from {G}rand {P}opo {B}each, {B}enin, forced by waves with frequency and directional spreading. {T}he generation of surf eddies by the 3{D} model differs from depth-averaged models, due to the vertical shear associated with shallow breaking waves. {I}n this case, the generation of eddies from both horizontal shear instability and the breaking of short-crested waves is hampered, the former by stretching the alongshore current and the latter by inhibiting the inverse energy cascade. {I}nstead, the vertical shear flow is subjected to forced wave group variability and {K}elvin-{H}elmholtz type instability at an inflection point. {P}rimary and secondary instabilities generate spanwise and streamwise vorticity connecting small-scale eddies to larger horizontal surfzone structures. {S}treamwise filaments, appearing as 5 m wide ribs or mini-rips, can extend beyond the surfzone but with moderate energy. {T}hese results appear consistent with the velocity spectra and observed patterns of tracers and suspended sediments at {G}rand {P}opo {B}each. {T}he timescale associated with the mean shear-induced turbulence is several times the wave period and suggests an intermediate range between breaker-induced turbulence and large-scale surf eddies.},
  keywords = {{S}urfzone ; {R}ip currents ; 3{D} instability ; {T}urbulent cascade ; {W}ave-resolving {RANS} model ; {BENIN} ; {GRAND} {POPO} {PLAGE}},
  booktitle = {},
  journal = {{O}cean {M}odelling},
  volume = {163},
  numero = {},
  pages = {101816 [20 ]},
  ISSN = {1463-5003},
  year = {2021},
  DOI = {10.1016/j.ocemod.2021.101816},
  URL = {https://www.documentation.ird.fr/hor/fdi:010082094},
}