# -*- coding: utf-8 -*-
import warnings
try:
from numpy import any as _any
except ImportError:
_any = any
[docs]def water_density(T=298.15, T0=None, units=None, a=None,
just_return_a=False, warn=True):
"""
Density of water (kg/m3) as function of temperature (K)
according to VSMOW model between 0 and 40 degree Celsius.
Fitted using Thiesen's equation.
Parameters
----------
T: float
Temperature (default: in Kelvin)
T0: float
Value of T for freezing point of water (default: 273.15)
units: object (optional)
object with attributes: Kelvin, meter, kilogram
a: array_like (optional)
5 parameters to the equation.
just_return_a: bool (optional, default: False)
Do not compute rho, just return the parameters ``a``.
warn: bool (default: True)
Emit UserWarning when outside temperature range.
Returns
-------
Density of water (float if T is float and units is None)
References
----------
TANAKA M., GIRARD G., DAVIS R., PEUTO A. and BIGNELL N.,
"Recommanded table for the density of water between 0 °C and 40 °C
based on recent experimental reports",
Metrologia, 2001, 38, 301-309. doi:10.1088/0026-1394/38/4/3
"""
if units is None:
K = 1
m = 1
kg = 1
else:
K = units.Kelvin
m = units.meter
kg = units.kilogram
m3 = m**3
if a is None:
a = (-3.983035*K, # C
301.797*K, # C
522528.9*K*K, # C**2
69.34881*K, # C
999.974950*kg/m3) # kg / m**3
if just_return_a:
return a
if T0 is None:
T0 = 273.15*K # K
t = T - T0
if warn and (_any(t < 0*K) or _any(t > 40*K)):
warnings.warn("Temperature is outside range (0-40 degC)")
return a[4]*(1-((t + a[0])**2*(t + a[1]))/(a[2]*(t + a[3])))
# generated at doi2bib.org:
bibtex = """
@article{Tanaka2001,
doi = {10.1088/0026-1394/38/4/3},
url = {http://dx.doi.org/10.1088/0026-1394/38/4/3},
year = {2001},
month = {aug},
publisher = {{IOP} Publishing},
volume = {38},
number = {4},
pages = {301--309},
author = {M Tanaka and G Girard and R Davis and A Peuto and N Bignell},
title = {Recommended table for the density of water between 0 ~C and 40
~C based on recent experimental reports},
journal = {Metrologia}
}
"""