STWAVE Usage & Theory Taylor Asher

Presentation Introduction Theory Numerical discretization Input/Output Wave action Wave spectrum Numerical discretization Input/Output Input files Model parameters Wave spectrum, wind, water level Output files Selected wave parameters Wave parameter fields Application

Theory Model assumptions Mild bottom slope, negligible reflection Spatially homogeneous offshore (boundary) Steady-state formulation Linear refraction & shoaling Depth-uniform current Frictionless bottom Linear radiation stress

Wave Action Steady-state conservation of spectral wave action NOTE sum of sources and sinks speed of propagation of wave packet wave phase speed kinetic+potential, per unit surface area self-explanatory relative to reference axis

Wave spectrum

Wave spectrum Bretschneider-Mitsuyasu spectrum, with peak frequency fp, and wind speed U with

Wave spectrum Directionalized spectrum, with magnitude-normalized directional term with normalization term

Numerical discretization Domain is made of a grid of NI by NJ square cells, Δx in length, with locally-defined axes Waves start at I=1, propagating toward I=NI No backward-propagation 35 angular bins ±87.5o

Input/Output

Input files Model parameters (options.std) IPRP: Switch for source/sink terms, such as wind waves, wave-wave interactions ICUR: Switch for current IBREAK: Switch for printing wave breaking IRS: Switch for calculating radiation stress gradient NSELCT: Number of special output points; 2-D wave spectra are generated for these points Points: (I,J) pairs for each point.

Input files Wave spectrum, wind, water level (spec.in) NF: Number of frequency bins NA: Number of direction bins (must be 35) Frequency vector of length NF, ordered smallest to largest (Hz) IDD: Integer event identifier U: Wind speed (m/s) UDIR: Wind direction (degrees) FM: Peak spectral frequency (Hz) DADD: Water elevation correction Wave spectrum (m2/s/Hz), ordered lowest frequency & -85 deg to 85 deg, to highest frequency -85 to 85

spec.in NF=25 NA=35 IDDD=200700 U=15 m/s UDIR=10 deg. FM=0.07 Hz DADD=-1 m

Output files Selected wave parameters (selhts.out) IDD: Integer event identifier (from spec.in) I: Integer x-grid cell index J: Integer y-grid cell index N: Integer number of point (points are 1 to NSELCT Hm0: Zeroth-moment (significant) wave height at cell (I,J) in meters Tp: Peak wave period at cell (I,J) in seconds αm: Mean wave direction at cell (I,J) in degrees

Output files Wave parameter fields (wavfld) NI, NJ: Grid dimension DXINC: Grid spacing IDD: Integer event identifier (as before) Wave height for each cell in wave field, ordered in the cross-shore direction from (1,NJ) to (NI,NJ), to (1,1) to (NI,1) Wave period for each cell in wave field, same ordering Wave direction for each cell in wave field, same ordering