A fan includes a rotatable center member that is centered relative to an axis of rotation of the fan. The fan includes a number of blades radially extending from the rotatable center member. Each blade may have one or more ribs extending therefrom non-parallel to the axis of rotation of the fan. Each blade may be may be flat in shape, except for the ribs extending therefrom, or it may have a cycloidal curvature that curves away from the direction in which the rotatable center member rotates. In addition to or in lieu of the ribs, each blade may have a side profile that is non-linear. The side profile may be a zigzag or a curvy shape. The side profile may have one or more notches pointed in a direction opposite that in which the rotatable center member rotates, or may have one or more holes extending through the blade.