A method of applying a riblet structure coating on the internal surface of a pipe includes coating the internal surface of a pipe with a resin layer and applying a cavity mold having a reverse riblet pattern structure to the coated internal surface of the pipe. A flexible air bag is inserted into the interior of the pipe and charged with air to hold the mold against the coated internal surface of the pipe. The air bag may be charged with air for a sufficient amount of time to allow the coating to cure in the riblet shape of the mold. Afterwards, the air bag and the mold are removed from the pipe to yield a pipe coated with an internal riblet structure.

Actuatable microstructures and methods of making the same are disclosed. An example a sheet includes a first side including an elastomeric material and a second side opposite the first side. The sheet defines sealed channels. In response to a pressure differential across the elastomeric material, the elastomeric material is to be in a deformed position relative to the sealed channels to define microstructures.

A vortex suppression device (10) for a fluid flowing along a pathway (A-E), including: an elongate body with an outer surface having an elongate leading section and an elongate trailing section along the length of the elongate body, in relation to a direction of fluid flow (A-E) when the device is located in the pathway, the elongate body having at least one channel (24a-24d, 26a, 26b) which extends from the elongate leading section to the elongate trailing section of the elongate body, the channel (24a-24d, 26a, 26b) being configured so that in use, when the device is in the pathway, the channel (24a-24d, 26a, 26b) allows fluid flow (J) towards the trailing section that disrupts the formation of vortices (D).

A riblet structure includes a plurality of wave-shaped riblets on a surface thereof, in which each of the riblets has a smaller peak height as an angle formed between a ridge line and a fluid flow direction becomes larger, a width between peak bases in a direction orthogonal to the fluid flow direction becomes smaller as the angle becomes larger, and an angle formed between a slope of a peak of the riblet and the surface at the peak base or a curvature at the peak base is identical at any position in a cross-sectional shape in the direction orthogonal to the fluid direction.

Thermal actuation of riblets is described herein. One disclosed example apparatus includes a riblet defining an aerodynamic surface of a vehicle. The disclosed example apparatus also includes a thermal expansion element within or operatively coupled to the riblet, wherein the thermal expansion element changes shape in response to a surrounding temperature, to displace a movable portion of the riblet relative to the aerodynamic surface to alter an aerodynamic characteristic of the vehicle.

Color applications for aerodynamic microstructures are disclosed herein. One disclosed example apparatus includes an aerodynamic microstructure of a vehicle, sub-microstructures superimposed on the aerodynamic microstructure, and a color application defined on or within the microstructure.

Low drag low noise devices are described herein that use passive jet flow control to reduce the drag and noise created by motor vehicles (e.g., motor vehicle side view mirrors and their main bodies) while the motor vehicles travel through a fluid. The low drag low noise devices described herein comprise a lengthwise axis, an outer body, and an inner body. The outer body and the inner body cooperatively define a channel through which fluid can pass during use.

A family of Radar energy Absorbing Deformable Low Drag Vortex Generators (RAD-LDVG) is described herein. This family of devices are fabricated in such a way that it can conform to aircraft surface features while reducing radar returns from structural details. Vortex generators (VGs) are typically used to reattach or smooth gross flowfields over aircraft surfaces. By doing so, an airfoil or wing can maintain attached flow at higher angles of attack and/or higher lift coefficients than one without the VGs. These devices are also used to reattach and/or smooth flows that encounter crossflow-induced instabilities and/or adverse pressure gradients on the upper surfaces of wings or near aircraft boattails. Other uses include reduction of buffet, vibration, flutter, cavity resonance or general bluff-body pressure drag reduction. Although conventional rigid VGs do generate vortical aerodynamic structures, two major problems are often experienced: i.) the inability to conform to curved surfaces, ii.) the generation of radar cross-section spikes produced by the VGs themselves.

A vortex suppressing sample probe for a fluid flowing along a pathway. The sample probe includes an elongate body with an outer surface having an elongate leading section and an elongate trailing section along the length of the elongate body, in relation to a direction of fluid flow when the device is located in the pathway. The elongate body can have at least one channel or groove which extends from the elongate leading section to the elongate trailing section of the elongate body. The channel or groove can be configured so that in use, when the device is in the pathway, the channel or groove allows fluid flow towards the trailing section that disrupts the formation of vortices. The groove can be a circumferential groove that follows a sinusoidal path around the outer surface of the elongate body.

An array of aerodynamic riblets is created by a plurality of high stiffness tips with a layer supporting the tips in predetermined spaced relation and adhering the tips to a vehicle surface.