def schoenherr(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_{F0}` for the skin friction
according to the Schoenherr line.
..math::
\\frac{0.242}{\sqrt{C_F}} = \log_{10} (C_F Re)
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if 'Re' in kwargs.iterkeys():
Re = kwargs['Re']
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
iteration = 100.0
for CdI in arange(0.001, 0.007, 0.00001):
if abs(0.242 / sqrt(CdI) - log(CdI * Re, 10)) < iteration:
iteration = 0.242 / sqrt(CdI) - log(CdI * Re, 10)
Cd = CdI
else:
return Cd
return 0.0
def schoenherr(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_{F0}` for the skin friction
according to the Schoenherr line.
..math::
\\frac{0.242}{\sqrt{C_F}} = \log_{10} (C_F Re)
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if "Re" in kwargs.iterkeys():
Re = kwargs["Re"]
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
iteration = 100.0
for CdI in arange(0.001, 0.007, 0.00001):
if abs(0.242 / sqrt(CdI) - log(CdI * Re, 10)) < iteration:
iteration = 0.242 / sqrt(CdI) - log(CdI * Re, 10)
Cd = CdI
else:
return Cd
return 0.0
def ittc57(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_D` for the skin friction
according to the ITTC'57 correlation line, which already accounts for
approximately 12% of pressure induced friction and should therefore
overestimate the skin friction of e.g. a plain turbulent plate.
..math::
C_F = \\frac{0.075}{(\log Re - 2)^2}
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if 'Re' in kwargs.iterkeys():
Re = kwargs['Re']
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
try:
return 0.075 / ((log(Re, 10) - 2)**2)
except TypeError:
return 0.075 / ((log10(Re) - 2)**2)
def ittc57(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_D` for the skin friction
according to the ITTC'57 correlation line, which already accounts for
approximately 12% of pressure induced friction and should therefore
overestimate the skin friction of e.g. a plain turbulent plate.
..math::
C_F = \\frac{0.075}{(\log Re - 2)^2}
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if "Re" in kwargs.iterkeys():
Re = kwargs["Re"]
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
try:
return 0.075 / ((log(Re, 10) - 2) ** 2)
except TypeError:
return 0.075 / ((log10(Re) - 2) ** 2)
def huges(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_{F0}` for the skin friction
according to the Hughes line. This is not used on a regular basis by the
model basins, but for simulations dealing with the turbulent flow over e.g.
a flat plate, this curve gives more accurate results to compare the CFD
results to.
..math::
C_{F0} = \\frac{0.066}{(\log Re - 2.03)^2}
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if 'Re' in kwargs.iterkeys():
Re = kwargs['Re']
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
return 0.066 / ((log(Re, 10) - 2.03)**2)
def huges(**kwargs):
"""
Calculates the viscous drag coefficient :math:`C_{F0}` for the skin friction
according to the Hughes line. This is not used on a regular basis by the
model basins, but for simulations dealing with the turbulent flow over e.g.
a flat plate, this curve gives more accurate results to compare the CFD
results to.
..math::
C_{F0} = \\frac{0.066}{(\log Re - 2.03)^2}
It is not necessary to hand a Reynoldsnumber to the function. If a velocity
or Froudenumber and a reference length is passed, the Reynoldsnumber is
derived accordingly.
:param Re: Reynoldsnumber
:type Re: float
:param Fr: Froudenumber
:type Fr: float
:param u: Velocity :math:`[\\frac{m}{s}]`
:type u: float
:param L: Reference length :math:`[m]`
:type L: float
:rtype: float
:Author: Jens Hoepken <*****@*****.**>
"""
if "Re" in kwargs.iterkeys():
Re = kwargs["Re"]
else:
u, Fr, Re = FlowProperties.uFrRe(**kwargs)
return 0.066 / ((log(Re, 10) - 2.03) ** 2)
