astringent, harsh, uneven, rough
澁 centers on a rough, puckering sensation: something astringent, harsh, or uneven in texture or manner. The meanings all point to a lack of smoothness or pleasantness.
澁 is an older form of 渋. It combines 氵 (water) with 歮, a component made of repeated 止 (stop) elements, suggesting water that does not flow smoothly—hence astringent or rough. The modern simplified form 渋 replaces the right side with a more compact shape.
Water 氵 that is stopped by repeated barriers 止止止 becomes stagnant and rough, like an astringent taste that makes your mouth pucker.
For ジュウ, imagine a rough, astringent juice that makes you pucker: juice -> ジュウ, and the harsh taste matches the kanji's meaning.