def one_phase_dP_acceleration(m, D, rho_o, rho_i):
    r'''This function handles calculation of one-phase fluid pressure drop
    due to acceleration for flow inside channels. This is a discrete 
    calculation, providing the total differential in pressure for a given  
    length and should be called as part of a segment solver routine.
    
    .. math::
        - \left(\frac{d P}{dz}\right)_{acc} = G^2 \frac{d}{dz} \left[\frac{
        1}{\rho_o} - \frac{1}{\rho_i} \right]

    Parameters
    ----------
    m : float
        Mass flow rate of fluid, [kg/s]
    D : float
        Diameter of pipe, [m]
    rho_o : float
        Fluid density out, [kg/m^3]
    rho_i : float
        Fluid density int, [kg/m^3]
        
    Returns
    -------
    dP : float
        Acceleration component of pressure drop for one-phase flow, [Pa]
        
    Notes
    -----

    Examples
    --------
    >>> one_phase_dP_acceleration(m=1, D=0.1, rho_o=827.1, rho_i=830)
    0.06848289670840459
    '''
    G = 4.0*m/(pi*D*D)
    return G*G*(1.0/rho_o - 1.0/rho_i)
r'''This function handles calculation of one-phase fluid pressure drop
    due to acceleration for flow inside channels. This is a discrete 
    calculation, providing the total differential in pressure for a given  
    length and should be called as part of a segment solver routine.
    
    .. math::
        - \left(\frac{d P}{dz}\right)_{acc} = G^2 \frac{d}{dz} \left[\frac{
        1}{\rho_o} - \frac{1}{\rho_i} \right]

    Parameters
    ----------
    m : float
        Mass flow rate of fluid, [kg/s]
    D : float
        Diameter of pipe, [m]
    rho_o : float
        Fluid density out, [kg/m^3]
    rho_i : float
        Fluid density int, [kg/m^3]
        
    Returns
    -------
    dP : float
        Acceleration component of pressure drop for one-phase flow, [Pa]
        
    Notes
    -----

    Examples
    --------
    >>> one_phase_dP_acceleration(m=1, D=0.1, rho_o=827.1, rho_i=830)
    0.06848289670840459