SWASH (Simulating WAves till SHore) is a general-purpose numerical tool for simulating unsteady, non-hydrostatic, free-surface, rotational flow and transport phenomena in coastal waters as driven by waves, tides, buoyancy and wind forces. It provides a general basis for describing wave transformations from deep water to a beach, port or harbour, complex changes to rapidly varied flows, and density driven flows in coastal seas, estuaries, lakes and rivers. It is continuously being developed by Delft University of Technology, the Netherlands.

SWASH accounts for the following physical phenomena:

  • wave propagation, shoaling, refraction and diffraction, frequency dispersion
  • nonlinear wave-wave interactions (including surf beat and triads)
  • wave breaking, runup and rundown
  • moving shoreline
  • bottom friction
  • wave damping induced by aquatic vegetation
  • partial reflection and transmission
  • wave interaction with structures
  • wave-current interaction, wave-induced currents
  • vertical turbulent mixing, subgrid turbulence
  • tidal waves, bores and flood waves
  • wind driven flows
  • space varying wind and atmospheric pressure
  • density driven flows
  • transport of suspended load for (non)cohesive sediment, turbidity flows
  • transport of tracer


  • Delft University of Technology


  • wave propagation in coastal areas
  • frequency dispersion
  • shoaling
  • refraction
  • diffraction
  • bottom friction
  • partial reflection and transmission
  • nonlinear wave-wave interactions