Parametric boundaries¶

What this shows: how to prescribe incoming waves by their parameters with BOUNDSPEC: the spectral shape, where the boundary is, and constant, varying or time-dependent values.

Prerequisites: Tutorial 4: Wave boundaries.

You will learn:

• how SHAPESPEC sets the spectral shape, the period and the directional spreading
• how to apply a boundary on a side or along a segment
• how to vary the parameters along the boundary and in time (TPAR files)

Data used: none; a TPAR file is created in the notebook.

Setup¶

In [1]:

import shutil
from pathlib import Path

import numpy as np
import pandas as pd

from rompy_swan.components.boundary import BOUNDSPEC
from rompy_swan.subcomponents.base import XY
from rompy_swan.subcomponents.boundary import (
    CONSTANTFILE,
    CONSTANTPAR,
    SEGMENT,
    SIDE,
    VARIABLEPAR,
)
from rompy_swan.subcomponents.spectrum import GAUSS, JONSWAP, PM, SHAPESPEC, TMA

OUT_DIR = Path("_output") / "boundaries_parametric"
shutil.rmtree(OUT_DIR, ignore_errors=True)
OUT_DIR.mkdir(parents=True)

import shutil from pathlib import Path import numpy as np import pandas as pd from rompy_swan.components.boundary import BOUNDSPEC from rompy_swan.subcomponents.base import XY from rompy_swan.subcomponents.boundary import ( CONSTANTFILE, CONSTANTPAR, SEGMENT, SIDE, VARIABLEPAR, ) from rompy_swan.subcomponents.spectrum import GAUSS, JONSWAP, PM, SHAPESPEC, TMA OUT_DIR = Path("_output") / "boundaries_parametric" shutil.rmtree(OUT_DIR, ignore_errors=True) OUT_DIR.mkdir(parents=True)

1. The spectral shape¶

SHAPESPEC becomes SWAN's BOUND SHAPESPEC command:

• shape: JONSWAP(gamma) (default, gamma=3.3), PM (Pierson-Moskowitz, fully developed sea), GAUSS(sigfr) (narrow swell), TMA(gamma, d) (JONSWAP in finite depth d) or BIN (all energy in one frequency bin);
• per_type: whether the period is the peak or the mean period;
• dspr_type: whether the spreading is given in degrees (directional standard deviation) or as the power m of cos^m.

In [2]:

for shape in [JONSWAP(gamma=3.3), PM(), GAUSS(sigfr=0.01), TMA(gamma=3.3, d=20.0)]:
    print(SHAPESPEC(shape=shape, per_type="peak", dspr_type="degrees").render())

for shape in [JONSWAP(gamma=3.3), PM(), GAUSS(sigfr=0.01), TMA(gamma=3.3, d=20.0)]: print(SHAPESPEC(shape=shape, per_type="peak", dspr_type="degrees").render())

BOUND SHAPESPEC JONSWAP gamma=3.3 PEAK DSPR DEGREES
BOUND SHAPESPEC PM PEAK DSPR DEGREES
BOUND SHAPESPEC GAUSS sigfr=0.01 PEAK DSPR DEGREES
BOUND SHAPESPEC TMA gamma=3.3 d=20.0 PEAK DSPR DEGREES

2. Where the boundary is¶

SIDE applies the boundary to a whole side of a regular grid. direction says which way positions along the side are counted, which matters for varying parameters.

In [3]:

jonswap = SHAPESPEC(shape=JONSWAP(gamma=3.3), per_type="peak", dspr_type="degrees")
swell = CONSTANTPAR(hs=2.0, per=12.0, dir=240.0, dd=20.0)

print(BOUNDSPEC(shapespec=jonswap, location=SIDE(side="west", direction="ccw"), data=swell).render())

jonswap = SHAPESPEC(shape=JONSWAP(gamma=3.3), per_type="peak", dspr_type="degrees") swell = CONSTANTPAR(hs=2.0, per=12.0, dir=240.0, dd=20.0) print(BOUNDSPEC(shapespec=jonswap, location=SIDE(side="west", direction="ccw"), data=swell).render())

BOUND SHAPESPEC JONSWAP gamma=3.3 PEAK DSPR DEGREES
BOUNDSPEC SIDE WEST CCW CONSTANT PAR hs=2.0 per=12.0 dir=240.0 dd=20.0

SEGMENT applies it along a line given by points (XY, in the problem coordinates) or by grid indices, for example the deep-water part of a side:

In [4]:

segment = SEGMENT(points=XY(x=[114.5, 114.5], y=[-32.8, -32.0]))
print(BOUNDSPEC(shapespec=jonswap, location=segment, data=swell).render())

segment = SEGMENT(points=XY(x=[114.5, 114.5], y=[-32.8, -32.0])) print(BOUNDSPEC(shapespec=jonswap, location=segment, data=swell).render())

BOUND SHAPESPEC JONSWAP gamma=3.3 PEAK DSPR DEGREES
BOUNDSPEC SEGMENT XY  &
    114.50000000 -32.80000000 &
    114.50000000 -32.00000000 &
    CONSTANT PAR hs=2.0 per=12.0 dir=240.0 dd=20.0

3. Parameters that vary along the boundary¶

VARIABLEPAR gives values at distances len along the side or segment, measured from its start in the counting direction. SWAN interpolates between them. Here the waves grow northwards along the western side, 1.3° long.

In [5]:

variable = VARIABLEPAR(
    hs=[1.5, 2.0, 2.5],
    per=[11.0, 12.0, 12.0],
    dir=[235.0, 240.0, 245.0],
    dd=[20.0, 20.0, 20.0],
    len=[0.0, 0.65, 1.3],
)
print(
    BOUNDSPEC(
        shapespec=jonswap, location=SIDE(side="west", direction="clockwise"), data=variable
    ).render()
)

variable = VARIABLEPAR( hs=[1.5, 2.0, 2.5], per=[11.0, 12.0, 12.0], dir=[235.0, 240.0, 245.0], dd=[20.0, 20.0, 20.0], len=[0.0, 0.65, 1.3], ) print( BOUNDSPEC( shapespec=jonswap, location=SIDE(side="west", direction="clockwise"), data=variable ).render() )

BOUND SHAPESPEC JONSWAP gamma=3.3 PEAK DSPR DEGREES
BOUNDSPEC SIDE WEST CLOCKWISE VARIABLE PAR & &
    	len=0.0 hs=1.5 per=11.0 dir=235.0 dd=20.0 & &
    	len=0.65 hs=2.0 per=12.0 dir=240.0 dd=20.0 & &
    	len=1.3 hs=2.5 per=12.0 dir=245.0 dd=20.0

4. Parameters that vary in time: TPAR files¶

A TPAR file holds a time series of wave height, period, direction and spreading, for example from a buoy or a wave model output point. write_tpar writes one from a pandas DataFrame indexed by time, with the columns in that order.

In [6]:

from rompy_swan.boundary import write_tpar

times = pd.date_range("2023-01-01", periods=7, freq="1h")
buoy = pd.DataFrame(
    {
        "hs": np.linspace(2.0, 3.0, len(times)),
        "tp": 12.0,
        "dir": np.linspace(240.0, 230.0, len(times)),
        "dspr": 20.0,
    },
    index=times,
)
write_tpar(buoy, OUT_DIR / "buoy.tpar")
print((OUT_DIR / "buoy.tpar").read_text())

from rompy_swan.boundary import write_tpar times = pd.date_range("2023-01-01", periods=7, freq="1h") buoy = pd.DataFrame( { "hs": np.linspace(2.0, 3.0, len(times)), "tp": 12.0, "dir": np.linspace(240.0, 230.0, len(times)), "dspr": 20.0, }, index=times, ) write_tpar(buoy, OUT_DIR / "buoy.tpar") print((OUT_DIR / "buoy.tpar").read_text())

TPAR
20230101.000000 2.00 12.00 240.00 20.00
20230101.010000 2.17 12.00 238.33 20.00
20230101.020000 2.33 12.00 236.67 20.00
20230101.030000 2.50 12.00 235.00 20.00
20230101.040000 2.67 12.00 233.33 20.00
20230101.050000 2.83 12.00 231.67 20.00
20230101.060000 3.00 12.00 230.00 20.00

CONSTANTFILE uses the same file along the whole side:

In [7]:

tpar_boundary = BOUNDSPEC(
    shapespec=jonswap,
    location=SIDE(side="west", direction="ccw"),
    data=CONSTANTFILE(fname="buoy.tpar", seq=1),
)
print(tpar_boundary.render())

tpar_boundary = BOUNDSPEC( shapespec=jonswap, location=SIDE(side="west", direction="ccw"), data=CONSTANTFILE(fname="buoy.tpar", seq=1), ) print(tpar_boundary.render())

BOUND SHAPESPEC JONSWAP gamma=3.3 PEAK DSPR DEGREES
BOUNDSPEC SIDE WEST CCW CONSTANT FILE fname='buoy.tpar' seq=1

VARIABLEFILE takes several files at distances along the boundary, like VARIABLEPAR. TPAR files have times, so the model needs MODE NONSTATIONARY, and the file must be in the workspace: copy it there, or let a data-driven boundary write it (Boundaries from spectra).

Summary¶

• SHAPESPEC sets the spectral shape, period type and spreading units.
• SIDE covers a whole side; SEGMENT a line of points or grid indices.
• CONSTANTPAR and VARIABLEPAR give fixed values; CONSTANTFILE and VARIABLEFILE give time series from TPAR files.
• A BOUNDSPEC covers one side or segment; for waves on every open side, use spectra (Tutorial 4).