Structured gas-containing surfaces

A structured surface which comprises, on a liquid-facing side:

• (i) liquid-repelling structures that form a gas-holding layer, the liquid-repelling structures being projections or protruding elements, and which are configured to at least temporarily hold a gas layer under the liquid;
• (ii) fluid-impermeable walls defining a multiplicity of self-contained compartments on at least a portion of the structured surface, the self-contained compartments including the liquid-repelling structures, wherein the walls have upper ends facing the liquid and a height, and wherein at least a portion of the walls are oriented parallel to a flow direction of the liquid and a remaining portion of the walls are not oriented parallel to the flow direction of the liquid;
• and
• (iii) rib structures positioned on the upper ends of the walls oriented parallel to the flow direction of the liquid and extending in the height direction from the upper ends of the walls oriented parallel to the flow direction of the liquid relative to the height of the walls not oriented parallel to the flow direction of the liquid, wherein the rib structures are parallel to the flow direction of the liquid, or parallel to a movement direction of the structured surface relative to the liquid, and wherein the rib structures are configured to project at least temporarily 0.1 μm to 10 mm from the gas layer into the liquid.