Fig. 4From: Light/dark cycle enhancement and energy consumption of tubular microalgal photobioreactors with discrete double inclined ribsTangential velocity vectors and streamlines at section z = 905 mm, a Type-1, b Type-2 and c Type-3; the solid lines in each streamline picture are critical light intensity when I0 = 375, 800 and 1200 μmol m−2 s−1 from the top to center, respectivelyBack to article page