cast (one's) eyes down
To look toward the ground, often because one feels embarrassed or ashamed. After I saw my ex-girlfriend walk into the store, I immediately cast my eyes down and then ducked behind the magazine rack for good measure. Because my son is so shy, he usually casts his eyes down whenever he meets someone.
cast one's eyes down
Fig. to tilt one's head or gaze downward. (Usually a sign of shame or to appear not to have seen someone.) She cast her eyes down as they saw each other again. He cast down his eyes in shame.