流淌 is a more literary and vivid two-character verb for 'to flow' — used for liquids, time, music, emotions. Compared to the simple 流 (liú, everyday 'flow'), 流淌 has a softer, poetic, or sustained feel, like water flowing quietly or emotions welling up. 淌 (tǎng) alone means 'to drip/trickle' (tears, sweat); 流淌 combines both characters for a richer, continuous flowing image.