How to use the fluids.constants.g function in fluids

.. [2] Bennett, Douglas L., M.W. Davies and B.L. Hertzler, The Suppression 
       of Saturated Nucleate Boiling by Forced Convective Flow, American 
       Institute of Chemical Engineers Symposium Series, vol. 76, no. 199. 
       91-103, 1980.
    .. [3] Bertsch, Stefan S., Eckhard A. Groll, and Suresh V. Garimella. 
       "Review and Comparative Analysis of Studies on Saturated Flow Boiling in
       Small Channels." Nanoscale and Microscale Thermophysical Engineering 12,
       no. 3 (September 4, 2008): 187-227. doi:10.1080/15567260802317357.
    '''
    G = m/(pi/4*D**2)
    Rel = D*G*(1-x)/mul
    Prl = Prandtl(Cp=Cpl, mu=mul, k=kl)
    hl = turbulent_Dittus_Boelter(Re=Rel, Pr=Prl)*kl/D
    Xtt = Lockhart_Martinelli_Xtt(x=x, rhol=rhol, rhog=rhog, mul=mul, mug=mug)
    F = ((Prl+1)/2.)**0.444*(1 + Xtt**-0.5)**1.78
    X0 = 0.041*(sigma/(g*(rhol-rhog)))**0.5
    S = (1 - exp(-F*hl*X0/kl))/(F*hl*X0/kl)
    
    hnb = Forster_Zuber(Te=Te, dPsat=dPsat, Cpl=Cpl, kl=kl, mul=mul, sigma=sigma,
                       Hvap=Hvap, rhol=rhol, rhog=rhog)
    return hnb*S + hl*F

--------
    Example compares terribly with the Ackers expression - probable error
    in [2]_. DO NOT USE.

    >>> Q_weir_rectangular_full_SIA(h1=0.3, h2=0.4, b=2)
    1.1875825055400384

    References
    ----------
    .. [1] Normen für Wassermessungen: bei Durchführung von Abnahmeversuchen an
       Wasserkraftmaschinen. SIA, 1924.
    .. [2] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
       Van Nostrand Reinhold Co., 1984.
    '''
    Q = 2/3.*2**0.5*(0.615 + 0.000615/(h1 + 0.0016))*b*g**0.5*h1 \
    + 0.5*(h1/(h1+h2))**2*b*g**0.5*h1**1.5
    return Q

def _Stichlmair_flood_f(inputs, Vl, rhog, rhol, mug, voidage, specific_area,
                        C1, C2, C3, H):
    '''Internal function which calculates the errors of the two Stichlmair
    objective functions, and their jacobian.
    '''
    Vg, dP_irr = float(inputs[0]), float(inputs[1])
    dp = 6.0*(1.0 - voidage)/specific_area
    Re = Vg*rhog*dp/mug
    f0 = C1/Re + C2/Re**0.5 + C3
    dP_dry = 0.75*f0*(1.0 - voidage)/voidage**4.65*rhog*H/dp*Vg*Vg
    c = (-C1/Re - 0.5*C2*Re**-0.5)/f0
    Frl = Vl*Vl*specific_area/(g*voidage**4.65)
    h0 = 0.555*Frl**(1/3.)
    hT = h0*(1.0 + 20.0*(dP_irr/H/rhol/g)**2)
    err1 = dP_dry/H*((1.0 - voidage + hT)/(1.0 - voidage))**((2.0 + c)/3.)*(voidage/(voidage-hT))**4.65 - dP_irr/H
    term = (dP_irr/(rhol*g*H))**2
    err2 = (1./term - 40.0*((2.0+c)/3.)*h0/(1.0 - voidage + h0*(1.0 + 20.0*term))
    - 186.0*h0/(voidage - h0*(1.0 + 20.0*term)))
    return err1, err2

while sill giving an answer. If at any point the tolerance is larger than
    1%, an exception is also raised.

    Examples
    --------
    >>> time_v_terminal_Stokes(D=1e-7, rhop=2200., rho=1.2, mu=1.78E-5, V0=1) 
    3.1880031137871528e-06
    >>> time_v_terminal_Stokes(D=1e-2, rhop=2200., rho=1.2, mu=1.78E-5, V0=1, 
    ... tol=1e-30)
    24800.636391801996
    '''
    if tol < 1e-17:
        tol = 2e-17
    term = D*D*g*rho - D*D*g*rhop 
    denominator = term + 18.*mu*V0
    v_term_base = g*D*D*(rhop-rho)/(18.*mu)

    const = D*D*rhop/mu*-1.0/18.
    for i in range(50):
        try:
            if v_term_base < V0:
                v_term = v_term_base*(1.0 + tol)
            else:
                v_term = v_term_base*(1.0 - tol)
            numerator = term + 18.*mu*v_term
            return log(numerator/denominator)*const
        except:
            tol = tol + tol
            if tol > 0.01:
                raise ValueError('Could not find a solution')
    raise ValueError('Could not find a solution')

Evaporators." International Journal of Refrigeration 35, no. 2 (March 
       2012): 325-35. doi:10.1016/j.ijrefrig.2011.11.002.
    .. [2] Huang, Jianchang. "Performance Analysis of Plate Heat Exchangers 
       Used as Refrigerant Evaporators," 2011. Thesis.
       http://wiredspace.wits.ac.za/handle/10539/9779
    .. [3] Amalfi, Raffaele L., Farzad Vakili-Farahani, and John R. Thome. 
       "Flow Boiling and Frictional Pressure Gradients in Plate Heat Exchangers.
       Part 1: Review and Experimental Database." International Journal of 
       Refrigeration 61 (January 2016): 166-84.
       doi:10.1016/j.ijrefrig.2015.07.010.
    .. [4] Eldeeb, Radia, Vikrant Aute, and Reinhard Radermacher. "A Survey of
       Correlations for Heat Transfer and Pressure Drop for Evaporation and 
       Condensation in Plate Heat Exchangers." International Journal of 
       Refrigeration 65 (May 2016): 12-26. doi:10.1016/j.ijrefrig.2015.11.013.
    '''
    do = 0.0146*angle*(2.*sigma/(g*(rhol - rhog)))**0.5
    Prl = Prandtl(Cp=Cpl, mu=mul, k=kl)
    alpha_l = thermal_diffusivity(k=kl, rho=rhol, Cp=Cpl)
    h = 1.87E-3*(kl/do)*(q*do/(kl*Tsat))**0.56*(Hvap*do**2/alpha_l**2)**0.31*Prl**0.33
    return h

h for water at atmospheric pressure on oxidized aluminum.

    >>> Rohsenow(rhol=957.854, rhog=0.595593, mul=2.79E-4, kl=0.680, Cpl=4217,
    ... Hvap=2.257E6, sigma=0.0589, Te=4.9, Csf=0.011, n=1.26)
    3723.655267067467

    References
    ----------
    .. [1] Cao, Eduardo. Heat Transfer in Process Engineering.
       McGraw Hill Professional, 2009.
    .. [2] Rohsenow, Warren M. "A Method of Correlating Heat Transfer Data for
       Surface Boiling of Liquids." Technical Report. Cambridge, Mass. : M.I.T.
       Division of Industrial Cooporation, 1951
    '''
    if Te is not None:
        return mul*Hvap*(g*(rhol-rhog)/sigma)**0.5*(Cpl*Te**(2/3.)/Csf/Hvap/(Cpl*mul/kl)**n)**3
    elif q is not None:
        A = mul*Hvap*(g*(rhol-rhog)/sigma)**0.5*(Cpl/Csf/Hvap/(Cpl*mul/kl)**n)**3
        return A**(1/3.)*q**(2/3.)
    else:
        raise ValueError('Either q or Te is needed for this correlation')

return Lombardi_Pedrocchi(m=m, x=x, rhol=rhol, rhog=rhog, sigma=sigma, D=D, L=L)
    elif Method2 == "Chisholm rough":
        return Chisholm(m=m, x=x, rhol=rhol, rhog=rhog, mul=mul, mug=mug, D=D, 
                     L=L, roughness=roughness, rough_correction=True)
    elif Method2 == "Zhang_Hibiki_Mishima adiabatic gas":
        return Zhang_Hibiki_Mishima(m=m, x=x, rhol=rhol, rhog=rhog, mul=mul, mug=mug, 
                     sigma=sigma, D=D, L=L, roughness=roughness, 
                     flowtype='adiabatic gas')
    elif Method2 == "Zhang_Hibiki_Mishima flow boiling":
        return Zhang_Hibiki_Mishima(m=m, x=x, rhol=rhol, rhog=rhog, mul=mul, mug=mug, 
                     sigma=sigma, D=D, L=L, roughness=roughness,
                     flowtype='flow boiling')
    elif Method2 == "Beggs-Brill":
        return Beggs_Brill(m=m, x=x, rhol=rhol, rhog=rhog, mul=mul, mug=mug, 
                     sigma=sigma, P=P, D=D, angle=angle, L=L, 
                     roughness=roughness, acceleration=False, g=g)
    else:
        raise ValueError(_unknown_msg_two_phase)

Engineering Chemistry Process Design and Development 9, no. 4
       (October 1, 1970): 553-58. doi:10.1021/i260036a010.
    .. [2] Gesellschaft, V. D. I., ed. VDI Heat Atlas. 2nd edition.
       Berlin; New York:: Springer, 2010.
    '''
    delta = (Djacket-Dtank)/2.
    Q = m/rho
    Pr = Cp*mu/k
    vs = Q/H/delta
    vo = Q/(pi/4*Dinlet**2)
    if dT is not None and isobaric_expansion is not None and inlettype == 'radial' and inletlocation is not None:
        if dT > 0: # Heating jacket fluid
            if inletlocation == 'auto' or inletlocation == 'bottom':
                va = 0.5*(2*g*H*isobaric_expansion*abs(dT))**0.5
            else:
                va = -0.5*(2*g*H*isobaric_expansion*abs(dT))**0.5
        else: # cooling fluid
            if inletlocation == 'auto' or inletlocation == 'top':
                va = 0.5*(2*g*H*isobaric_expansion*abs(dT))**0.5
            else:
                va = -0.5*(2*g*H*isobaric_expansion*abs(dT))**0.5
    else:
        va = 0
    vh = (vs*vo)**0.5 + va
    dg = (8/3.)**0.5*delta
    Res = vh*dg*rho/mu
    if muw is not None:
        NuSL = (0.03*Res**0.75*Pr)/(1 + 1.74*(Pr-1)/Res**0.125)*(mu/muw)**0.14
    else:
        NuSL = (0.03*Res**0.75*Pr)/(1 + 1.74*(Pr-1)/Res**0.125)
    return NuSL*k/dg

2\sqrt{2}/3

    Examples
    --------
    p. 578 in [1]_, matches exactly.

    >>> Nusselt_laminar(Tsat=370, Tw=350, rhog=7.0, rhol=585., kl=0.091,
    ... mul=158.9E-6, Hvap=776900, L=0.1)
    1482.206403453679

    References
    ----------
    .. [1] Hewitt, G. L. Shires T. Reg Bott G. F., George L. Shires, and
       T. R. Bott. Process Heat Transfer. 1E. Boca Raton: CRC Press, 1994.
    '''
    return 2.*2.**0.5/3.*(kl**3*rhol*(rhol - rhog)*g*sin(angle/180.*pi)
                          *Hvap/(mul*(Tsat - Tw)*L))**0.25

Returns
    -------
    Bo : float
        Bond number []

    Examples
    --------
    >>> Bond(1000., 1.2, .0589, 2)
    665187.2339558573

    References
    ----------
    .. [1] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
       Eighth Edition. McGraw-Hill Professional, 2007.
    '''
    return (g*(rhol-rhog)*L*L/sigma)