fix: correct r_in/r_out mapping and guard Reff division by zero

        R_f_out_out = 1.0 / (h_f_a_out * 2 * np.pi * r_out_in)

        R_fp = R_p_out + R_f_out_out

        r_inner = np.roll(self.r_in, 1)

        r_outer = np.roll(self.r_out, 1)

        # r_inner = np.roll(self.r_in, 1)

        # r_outer = np.roll(self.r_out, 1)

        r_inner = self.r_in

        r_outer = self.r_out

        self.coaxial = gt.pipes.Coaxial(

            (0, 0), r_inner, r_outer, self.b, k_s, k_g[0], R_ff, R_fp, J=self.J

        if abs(np.sum(qbz) - power) > 1:

            print("power is not sumq (sumq, power):", np.sum(qbz), ",", power)

        # Reff = -np.average(Tf - Tb) * bh.H / (power + 1e-6)

        if abs(power) > 1e-3:

            Reff = -np.average(Tf - Tb) * bh.H / power

        else:

            Reff = -1

        return T_f_out, power, Reff, ptemp, Tb, qbz