def METHOD_NAME(h, eta, u, v, w, kappa, tracer):
    """Compute residual of advection-diffusion equation"""
    adv = sympy.diff(tracer*u, x) + sympy.diff(tracer*v, y) + sympy.diff(tracer*w, z)
    stress = kappa*(sympy.diff(tracer, x) + sympy.diff(tracer, y))
    diff = sympy.diff(stress, x) + sympy.diff(stress, y)
    res = adv + diff
    return res