Device, assembly, and system for reducing aerodynamic drag

A land vehicle configured to move relative to surrounding air and being subject to an air drag due to a relative velocity between the vehicle and the air, the land vehicle comprising:

• a body with a surface subject to an air flow as the vehicle moves relative to the surrounding air;
• a vortex flow generating device on the surface of the vehicle configured to substantially reduce the air drag as the vehicle moves relative to the surrounding air, said vortex flow generating device comprising:
• a vortex-generating element on the surface of the vehicle subject to air flow having a given velocity relative to the surface as the vehicle moves relative to the surrounding air, said element being disposed to face into the air flow;
• said vortex-generating element having at least one wall generally extending in a direction of the air flow and in an upward direction and said at least one wall being shaped to impose on the flowing air a vorticity component, the upward direction being defined by a surface normal to the surface of the vehicle that is subject to the air flow;
• and
• a boundary wall forming a roof for said vortex-generating element separate from said vortex-generating element, said roof being disposed and configured to form a confined flow channel together with said at least one wall of said vortex-generating element and to limit an upward flow of the air upwardly away from said vortex-generating element and upwardly away from the surface of the vehicle;
• wherein said vortex-generating element is mounted rigidly and immovably relative to said roof defined by said boundary wall, and said confined flow channel has a forward opening facing into the air flow and a rear opening;
• wherein the air enters said forward opening having an energy substantially defined by a mass and a speed of the air flow, and the air exits the rear opening in a vortex flow having an energy substantially defined by the mass, the speed of the air flow, and a rotational velocity of the vortex flow exiting said rear opening.