def Ndavies(r,g,eta,drho,rho):
    """Davies (Best) number

    Args:
        r: particle size (cm)
        g: gravity (cm/s2)
        eta: dynamic viscosity (g/s/cm)
        drho: density difference between condensates and atmosphere (g/cm3)
        rho: atmosphere density (g/cm3)

    Returns:
       Davies number (Best Number)

    """
    return 32.0*g*r**3*drho*rho/(3.0*eta**2)