US 2026/0274377 A1Published application

Plastron trapping trenches and uses thereof

AssigneeThe Regents of the University of California

InventorsChang-Jin Kim, Ning Yu

Life of this patent

Estimating the term…

Loading patent…

Abstract

The invention, according to one embodiment, discloses the geometric (i.e., shape) and dimensional (i.e., size) details and other properties of trenches that can retain trapped gas under a fluid such as water (called “plastron”) while subjected to the flow conditions common for traveling watercraft. A solid surface of numerous trenches filled with air allows the surface to experience a smaller friction drag in flowing water. Retainment of the plastron under high-speed conditions of regular watercraft has proved elusive. Here, the geometric and dimensional details of the trenches are disclosed that can retain the plastron under the flow conditions common for watercraft—under the shear rate of water flow that a boat traveling even over 10 knots would experience. The trenches may also be applied to other objects or surface that come into contact with flowing fluid.

Claims16

Dependent claims

A solid surface having a plurality of trenches for maintaining a plastron on the solid surface during flow of a fluid over the solid surface, wherein the trenches are defined by a leading end and a trailing end, a bottom surface and trench tops, wherein each trench of the plurality of trenches satisfies the following conditions:

(a) a width (w) of an opening between the trench tops arranged with a pitch (p) is within the range of 10 μm and 100 μm;
(b) a pitch (p) and a width (p−w) of the trench tops are arranged so that a gas fraction (Ø=w/p) of the trench tops is equal to or larger than 70% (Ø≥0.7);
(c) a depth (d) of the trench is greater than w/2;
(d) a thickness (t) of the trench tops is equal to or larger than a width of the trench tops (p−w) and equal to or smaller than the trench depth (d) (p−w≤t≤d);
(e) a length (L) of each trench is between 1 cm and 20 cm;
(f) the trench tops comprise respective top edges having a radius of curvature (r) smaller than 10 microns;
(g) wherein the trench tops comprise side surfaces and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (θw) larger than 100 degrees (θw>100°);
(h) wherein the leading ends and trailing ends comprise side surfaces and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (w) larger than 100 degrees (θw>100°);
(i) wherein the trench comprises a bottom surface and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (θw) larger than 100 degrees (θw>100°);
and
(j) wherein the trench tops are aligned nominally parallel to a flow direction of the fluid over the solid surface and the top surfaces of the trench tops are substantially flush relative to one another and to top surfaces of the leading end and the trailing end.

8 more elements

(a) a width (w) of an opening between the trench tops arranged with a pitch (p) is within the range of 10 μm and 100 μm;
(b) a pitch (p) and a width (p−w) of the trench tops are arranged so that a gas fraction (Ø=w/p) of the trench tops is equal to or larger than 70% (Ø≥0.7);
(c) a depth (d) of the trench is greater than w/2;
(d) a thickness (t) of the trench tops is equal to or larger than a width of the trench tops (p−w) and equal to or smaller than the trench depth (d) (p−w≤t≤d);
(e) a length (L) of each trench is between 1 cm and 20 cm;
(f) the trench tops comprise respective top edges having a radius of curvature (r) smaller than 10 microns;
(g) wherein the trench tops comprise side surfaces and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (θw) larger than 100 degrees (θw>100°);
(h) wherein the leading ends and trailing ends comprise side surfaces and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (θw) larger than 100 degrees (θw>100°);
(i) wherein the trench comprises a bottom surface and substantial portions thereof are hydrophobic with a local (intrinsic) contact angle of water (θw) larger than 100 degrees (θw>100°);
(j) wherein the trench tops are aligned nominally parallel to a flow direction of the fluid over the solid surface and the top surfaces of the trench tops are substantially flush relative to one another and to top surfaces of the leading end and the trailing end;
(k) wherein the trench tops are continuous between the leading end and the trailing end;
and
(l) wherein all of the trench tops contact the bottom surface.

10 more elements

Dependencies are inferred from the claim text.