def np_flux_special(cx, cy, gcx, gcy, gvx, gvy, ux, uy, Dx, Dy, z, T, p):
    """
     Calculate the flux component of the Nernst-Planck equation on a MACs grid

     Parameters
     ------------

    c:     concentration
    gcx:   concentration gradient, x component
    gcy:   concentration gradient, y component
    gvx:   voltage gradient, x component
    gvy:   voltage gradient, y component
    ux:    fluid velocity, x component
    uy:    fluid velocity, y component
    D:     diffusion constant, D
    z:     ion charge
    T:     temperature
    p:     parameters object

    Returns
    --------
    fx, fx        mass flux in x and y directions
    """
    alphax = Dx * z * p.q / (p.kb * T)
    alphay = Dy * z * p.q / (p.kb * T)
    fx = -Dx * gcx - alphax * gvx * cx + cx * ux
    fy = -Dy * gcy - alphay * gvy * cy + cy * uy
    return fx, fy
