Best to use something specifically formulated for plants.
The air movement strengthens stems and promotes transpiration. It hits the stomata with additional CO2. Stomata are the little pores on the leaf. Kinda like a mouth that allows gases like oxygen, CO2 and water vapor to enter and leave the plant.

If it's not an oscillating fan, ok not to keep it directly on the plant 24/7. Would risk wind burn. If it is an oscillating fan, let the air sweep back and forth directly on the plants. (lowest setting when young)

The shot from above the plant looks great.