The present invention relates to structured, gas-holding surfaces for improving the friction-reducing properties of gas layers held under a liquid and for the simultaneous suppression of turbulence. The present invention furthermore relates to a device comprising this structured, gas-holding surface and to the use of this structured, gas-holding surface.

In the absence of inventive practice, the hydrodynamic flows on both sides of a vertically oriented bluff body (e.g., cylinder) traveling through water tend to hug the bluff body proximate its curved back surface and to converge behind the bluff body, resulting in lateral sway of the bluff body. Exemplary inventive practice provides for attachment of a pair of waterjet-streaming devices at opposite axial ends of a bluff body such as a cylinder. The waterjet streams discharged by the two inventive devices, which adjoin the vertical bluff body, deflect the hydrodynamic flows on both curved side surfaces of the bluff body. The inventive apparatus thereby encourages a continued approximate parallelity of the hydrodynamic flows behind the bluff body, resulting in significantly greater stability of the bluff body. Some exemplary embodiments of the present invention provide for attachment of a single waterjet-streaming device at one axial end of the bluff body.

In the absence of inventive practice, the hydrodynamic flows on both sides of a vertically oriented bluff body (e.g., cylinder) traveling through water tend to hug the bluff body proximate its curved back surface and to converge behind the bluff body, resulting in lateral sway of the bluff body. Exemplary inventive practice provides for attachment of a pair of waterjet-streaming devices at opposite axial ends of a bluff body such as a cylinder. The waterjet streams discharged by the two inventive devices, which adjoin the vertical bluff body, deflect the hydrodynamic flows on both curved side surfaces of the bluff body. The inventive apparatus thereby encourages a continued approximate parallelity of the hydrodynamic flows behind the bluff body, resulting in significantly greater stability of the bluff body. Some exemplary embodiments of the present invention provide for attachment of a single waterjet-streaming device at one axial end of the bluff body.

An aerodynamic or hydrodynamic wall surface has an array of fibrillar structures disposed on and extending from the wall surface, wherein each fibrillar structure comprises a stalk and a tip. The stalk has a first end and a second end, wherein the first end is attached to the wall surface, and the stalk is oriented with respect to the wall surface at a stalk angle between approximately 1 degrees and 179 degrees. The tip has a first side and a second side, wherein the first side is attached proximate to the second end of the stalk, the tip has a larger cross-sectional area than the stalk, and the second side comprises a substantially planar surface that is oriented with respect to the stalk at a tip angle between approximately 0 degrees and 90 degrees.

An aerodynamic or hydrodynamic wall surface has an array of fibrillar structures disposed on and extending from the wall surface, wherein each fibrillar structure comprises a stalk and a tip. The stalk has a first end and a second end, wherein the first end is attached to the wall surface, and the stalk is oriented with respect to the wall surface at a stalk angle between approximately 1 degrees and 179 degrees. The tip has a first side and a second side, wherein the first side is attached proximate to the second end of the stalk, the tip has a larger cross-sectional area than the stalk, and the second side comprises a substantially planar surface that is oriented with respect to the stalk at a tip angle between approximately 0 degrees and 90 degrees.

A viscous-drag-reducing cladding for a ship's hull whereby the wetted area of the hull is reduced by interspersing air between the hull surface and the water. A substantial portion of the submerged area of the ship's hull comprises densely packed air pockets. The dimension of the air pocket is less than twice the capillary length of water. Each air pocket is supplied with pressurised gas by means of a restrictor. The pressurised air is supplied to each air pocket by means of a network of corrugated channels.

The novel bladder systems and tie down systems set forth herein provide systems and apparatuses that mitigate or prevent damage, such as tipping over/capsizing, of a watercraft stored on shore or an aircraft secured to a ground surface during adverse wind, rising water, or storm events. Further, novel apparatuses and methods for storing a watercraft using the bladders as cushioning or holding devices when installed within a cavity, whether the cavity is created by digging a hole or building an enclosing berm, provides additional stability and security for the watercraft during adverse wind, rising water, or storm events.

The novel bladder systems and tie down systems set forth herein provide systems and apparatuses that mitigate or prevent damage, such as tipping over/capsizing, of a watercraft stored on shore or an aircraft secured to a ground surface during adverse wind, rising water, or storm events. Further, novel apparatuses and methods for storing a watercraft using the bladders as cushioning or holding devices when installed within a cavity, whether the cavity is created by digging a hole or building an enclosing berm, provides additional stability and security for the watercraft during adverse wind, rising water, or storm events.

A generally cylindrical element 10 that is adapted for immersion in water is described. The generally cylindrical element 10 has an outer surface 11 that is in contact with the water in use. The outer surface 11 has at least two rows of repeating shapes 20, for example hexagons 20, provided on the surface 11, where each row of repeating shapes 20 is separated from the other or the adjacent row(s) by a groove arrangement 30. Each shape 20 within a row is separated from the, or each, adjacent shape 20 by at least one groove 30. This configuration of the surface 11 reduces Vortex Induced Vibration (VIV) and/or drag that may act upon the generally cylindrical element 10 when it is immersed in a body of water.

A generally cylindrical element 10 that is adapted for immersion in water is described. The generally cylindrical element 10 has an outer surface 11 that is in contact with the water in use. The outer surface 11 has at least two rows of repeating shapes 20, for example hexagons 20, provided on the surface 11, where each row of repeating shapes 20 is separated from the other or the adjacent row(s) by a groove arrangement 30. Each shape 20 within a row is separated from the, or each, adjacent shape 20 by at least one groove 30. This configuration of the surface 11 reduces Vortex Induced Vibration (VIV) and/or drag that may act upon the generally cylindrical element 10 when it is immersed in a body of water.