Patent Publication Number: US-11019855-B2

Title: Vortex-generator device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application 62/513,238 filed on May 31, 2017 and entitled Vortex-Generator Device. The entirety of the aforementioned application is incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a plurality of vortex generators that are interconnected with one another. 
     BACKGROUND 
     Vortex generators typically include some type of protuberance extending from a surface of a body and configured disrupt a boundary layer of a fluid (e.g., air, water, etc.) passing over the surface. As such, in some instances, the vortex generators affect drag properties when the body is in motion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This disclosure describes various subject matter, some of which is depicted in the figures that are briefly described below and that are incorporated herein by reference. 
         FIG. 1A  depicts an upper-body garment that includes a vortex-generator device in accordance with an aspect of this disclosure. 
         FIG. 1B  depicts a cross-section view taken from the cross-section reference plane indicated in  FIG. 1A . 
         FIG. 1C  depicts a cross-section view taken from the cross-section reference plane indicated in  FIG. 1B . 
         FIGS. 2A, 2B, and 2C  each depict a respective vortex-generator device having respective dimensional characteristics in accordance with other aspects of this disclosure. 
         FIG. 3  depicts an alternative vortex-generator device in accordance with an aspect of this disclosure. 
         FIGS. 4A and 4B  depict other types of articles that might include a vortex-generator device in accordance with aspects of this disclosure. 
         FIG. 5A  depicts an adhesive-tape strip coupled with a vortex-generator device in accordance with an aspect of this disclosure. 
         FIG. 5B  depicts a cross-section view taken from the cross-section reference plane indicated in  FIG. 5A . 
         FIG. 6  depicts a perspective view of a vortex-generator device in accordance with an aspect of this disclosure. 
         FIG. 7  depicts a flow chart showing steps performed in a method of making a vortex-generator device and coupling the vortex-generator device to an article in accordance with an aspect of this disclosure. 
         FIG. 8  depicts a jig for attaching a vortex-generator device to an article in accordance with an aspect of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Subject matter is described throughout this disclosure in detail and with specificity in order to meet statutory requirements. But the aspects described throughout this disclosure are intended to be illustrative rather than restrictive, and the description itself is not intended necessarily to limit the scope of the claims. Rather, the claimed subject matter might be practiced in other ways to include different elements or combinations of elements that are equivalent to the ones described in this disclosure. In other words, the intended scope of the claims, and the other subject matter described in this specification, includes equivalent features, aspects, materials, methods of construction, and other aspects not expressly described or depicted in this application in the interests of concision, but which would be understood by an ordinarily skilled artisan in the relevant art in light of the full disclosure provided herein as being included within the scope. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     This disclosure describes an article that includes a vortex-generator device affixed to a surface. The vortex-generator device generally includes at least one elongate member that interconnects two or more vortex generators. The vortex-generator device might be affixed to a variety of different articles, such as a garment, clothing accessory (e.g., footwear, gloves, headwear, etc.), adhesive tape, athletic equipment, and the like in order to affect drag properties of the article. Among other things, features of the vortex-generator device may provide stability to each of the individual vortex generators and may provide a mechanism by which the two or more vortex generators can be handled collectively, instead of individually, such as when the vortex-generator device is affixed to the article. In additional instances, the vortex-generator device may affect properties of the underlying article, such as by reducing relative stretch in a portion of the article. 
     One aspect of the disclosure includes an article of apparel having a material layer, an elongate member coupled to a surface of the material layer, and a first and second vortex generator coupled to the elongate member. The elongate member has an elongate-member length and an elongate-member width. The elongate-member length extends from the first vortex generator to the second vortex generator, and the elongate-member width is less than the elongate-member length. In addition, each of the first vortex generator and the second vortex generator includes a leading edge and a trailing edge opposite the leading edge. The leading edge and the trailing edge define a vortex-generator length therebetween, and the elongate-member width and the vortex-generator length comprise a ratio in a range of about 1.5:1 to about 0.25:1. 
     Another aspect of the disclosure includes an article with a vortex-generator device. The article includes a material layer having a surface. A plurality of elongate members is coupled to the surface, and the elongate members are interconnected with one another. In addition, each elongate member of the plurality of elongate members includes an elongate-member length and an elongate-member width, the elongate-member width being less than the elongate-member length. Further, at least two elongate members included in the plurality of elongate members intersect at a vertex to form an angle. The article also includes a plurality of vortex generators that are coupled to the plurality of elongate members and that protrude away from the surface. Each elongate-member length extends between a respective pair of vortex generators, and at least one of the vortex generators is coupled at the vertex. 
     A further aspect of the disclosure is directed to a method of constructing a vortex-generator device. The method includes filling a vortex-generator-device mold with an elastomeric composition in a first state. The vortex-generator-device mold includes a plurality of vortex-generator-shaped depressions having a first depth and one or more grooves connecting the vortex-generator shaped depressions to one another. The one or more grooves have a second depth that is less than the first depth. The elastomeric composition is cured to a second state while the elastomeric composition is in the vortex-generator-device mold, such that the elastomeric composition forms a vortex-generator device when cured. The method also includes applying a bonding agent to a surface of the vortex-generator device, the surface being positioned near a mouth of the one or more grooves. The bonding agent is cured while the vortex-generator device is in the vortex-generator device mold. The vortex-generator device is transferred to a jig having a cavity shape that is complementary to the vortex-generator device, such that the surface with the bonding agent is exposed. A material layer is placed against the surface with the bonding agent, and the bonding agent is activated to couple the vortex-generator device to the material layer. 
     Having described various aspects of the present disclosure, reference will now be made to the figures to further describe these aspects, as well as other aspects.  FIG. 1A  depicts one type of article  10  that includes a vortex-generator device  12  coupled thereto. The article  10  includes an upper-torso garment, which is exemplary of one type of garment to which the vortex-generator device  12  might be coupled.  FIG. 1A  also includes a magnified view that depicts portions of the vortex-generator device  12  in greater detail for illustrative purposes. In addition,  FIGS. 1B and 1C  illustrate respective cross sections that depict other aspects of the vortex-generator device. The depictions provided by  FIGS. 1B and 1C  are schematic in nature and are not necessarily meant to illustrate or depict accurate scaling of layer thickness or vortex-generator-device sizing or spacing. 
     As depicted in the magnified view, the vortex-generator device  12  includes an elongate member  14 , which is coupled to a surface  16  of the article  10 . In addition, a first vortex generator  18  and a second vortex generator  20  are coupled to the elongate member  14 . The vortex generators  18  and  20  make up a subset of a larger number of vortex generators, which are illustrated on the non-magnified view of the article  10 , and the larger number of vortex generators depicted on the article  10  are interconnected by a series of other elongate members. When the article  10  is in use, such as when a person wearing the article  10  is in motion (e.g., running, jumping, sprinting, etc.), the vortex generators  18  and  20  protrude away from the surface  16  and operate to disrupt a boundary layer, thereby affecting drag properties of the article  10 . Among other things, the elongate member  14  provides additional support and stability for the vortex generators  18  and  20  and may also affect properties of the article  10 . 
     Generally, an elongate member (e.g., elongate member  14 ) includes a body that extends in three dimensions (e.g., x, y, and z axes), such that the body has an elongate-member length, an elongate-member width, and an elongate-member thickness, the elongate-member length being larger than the elongate-member width and the elongate-member thickness. Examples of an elongate-member length  22 , an elongate-member width  24 , and an elongate-member thickness  26  are illustratively depicted in  FIGS. 1A-1C . That is, the elongate member  14  includes an elongate-member length  22 , which extends from the first vortex generator  18  to the second vortex generator  20 , and in this respect, the dimensionality of the elongate member (i.e., in which axis the length extends in the three-dimensional reference space) may be determined by the two vortex generators  18  and  20 . The two vortex generators  18  and  20  may represent terminal endpoints of the elongate member  14 , or the elongate member  14  may extend past the vortex generators as depicted in  FIG. 1 . The length  22  may be measured by a straight line when the elongate member is straight. And in instances in which the elongate member is not straight (e.g., curved, zigzag, etc.), then the length may be measured as the traced length of the elongate member from one point to another point. 
     The elongate member  14  also includes sides or edges  28  and  30  ( FIG. 1C ) that extend along the length of the elongate member  14 . The width  24  is measured from one side to the other side along an axis perpendicular to the length  22  at a point on the elongate member  14 , and generally, the width is smaller than the length  22 . Furthermore, the elongate member  14  includes a first surface  32  that faces towards the article surface  16  and a second surface  34  that faces in a direction opposite from the first surface  32 , and the first and second surfaces  32  and  34  also extend along the length of the elongate member  14 . The thickness  26  is measured from one surface to the other surface along an axis perpendicular to the width  24  and is generally smaller than the length  22 . The cross-sectional view of the elongate member  14  provided in  FIG. 1C  illustrates a rectangular cross-section, and in other aspects, the elongate member  14  may include various other cross sections, including (but not limited to) circular, ovular, square, polygonal, semi-circular, semi-ovular, and organically shaped. 
     Generally, a vortex generator includes a protuberance that extends away from the article surface  16  and that is configured to engage the boundary layer of a fluid medium passing over the surface. A vortex generator may include various shapes and configurations, including (but not limited to) dart-shaped, vane-shaped, triangular, hemispherical, cylindrical, polygonal prismatic, polygonal pyramidal, and the like. The exemplary vortex generators  18  and  20  depicted in  FIGS. 1A-1C  are dart shaped. 
     A vortex generator may include various dimensions, such as a vortex-generator length and a vortex-generator height. As depicted in the magnified view of  FIG. 1A , the vortex generator  18  includes a vortex-generator length  42  extending from a leading edge  36  to a trailing edge  38 . Typically, the leading edge is oriented on a surface to face in a direction opposite to the direction in which a fluid (e.g., water or air) passes, such as when the fluid is flowing over the surface or when the surface moves through the fluid. The trailing edge faces towards the direction in which the fluid is flowing or in which the fluid passes when the article moves. Accordingly, the leading edge is oriented to engage the fluid before the trailing edge, and the trailing edge is “downstream” of the leading edge. For example, when the article  10  is worn by a person moving in a forward direction, air would flow in the direction of the arrow  40 , such that the leading edge  36  would engage the air flow before the trailing edge  38 . Although vortex generators arranged on the article  10  include the dart-shaped configuration depicted in  FIGS. 1A-1C , any alternative vortex-generator configuration or shape would similarly include a leading edge facing opposite the arrow  40  and a trailing edge facing in the same direction as the arrow  40 . 
     The vortex-generator device  12  includes additional features as well. For example, as described in other parts of this disclosure, the vortex-generator device  12  is coupled to the surface  16  of the article  10 , which is formed by a textile layer  43 . In one aspect, the vortex-generator device  12  is bonded or adhered to the surface  16 , such that a bonding-material layer  44  is layered directly between the surface  32  of the elongate member and the surface  16  of the article. As such, the surface  16  includes a first surface portion  46  that engages with the bonding layer  44  and that is attached directly to the vortex-generator device. The first surface portion  46  is formed by a first set of yarn strands  48  (or fibers), which might be formed into the textile layer by various manufacturing techniques, including knitting, woven, non-woven, braiding, and the like. In addition, the surface  16  includes a second surface portion  50  that is directly adjacent to the first surface portion  46  and that does not engage with the bonding layer  44 . The second surface portion  50  is formed by a second set of yarn strands  52  (or fibers), which are likewise used to form the textile layer  43 . The vortex-generator device  12  might be coupled to the surface  16  in other manners as well. For example, the vortex-generator device  12  might be 3D printed onto the surface  16 , ultrasonic welded to the surface  16 , molded directly onto the surface  16 , or affixed by some other manufacturing technique. 
     The attachment of the vortex-generator device  12  on the underlying textile layer  43  may operate in various manners in combination with the textile layer  43 . For example, if the elongate member is constructed of a material having a higher modulus of elasticity than the textile layer  43 , then the first set of yarns strands  48  that are directly engaged with the vortex-generator device  12  may have a lower amount of stretch under a given force as compared with the second set of yarn strands  52  under the same given force. As such, coupling the vortex-generator device  12  to the textile layer  43  might create an amount of lockout or higher compression in particular zones or regions of the article  10 . In some instances, the additional compression or lockout might be localized directly beneath the vortex-generator device. And in other aspects, the higher compression and lockout might be realized across a larger region of the garment that is included among the footprint of the vortex-generator device. For example, the region  54  of the article  10  included within the footprint of the vortex-generator device  12  might have a higher modulus of elasticity and more compression than the region  56  of the article  12 . 
     The vortex-generator device  12  includes relative dimensions between the vortex generator  18  and the elongate member  14 , which may at least partially determine a degree to which the vortex-generator device affects properties of the article. To further illustrate this aspect of the present disclosure,  FIGS. 2A-2C  depict alternative vortex-generator devices  12 A,  12 B, and  12 C, respectively, in which the relative sizes of the elongate members and the vortex-generator length varies. For example, in  FIG. 2A , the vortex-generator length  42 A is similar to the elongate-member width  24 A; in  FIG. 2B , the vortex-generator length  42 B is larger than the elongate-member width  24 B; and in  FIG. 2C , the vortex-generator length  42 C is smaller than the elongate-member width  24 C. The dimensionality of the vortex-generator device  12  may operate in various manners to affect one or more properties of the article. In one aspect, the respective size of the elongate member relative to the vortex generator may balance the added stabilization of the vortex generators (as provided by the elongated member) with an amount of additional weight and an amount of additional compression or lockout contributed by the elongate member. For example, in instances in which greater compression and lockout is desired, the elongate member may be configured to include a larger width, such as in  FIG. 2C . And to achieve lower amounts of compression, the configuration of  FIG. 2B  might be constructed. In this sense, the size of the elongate members may be tuned to achieve desired features and functionality. 
     As such, the relative dimensions of the elongate members and the vortex generators may vary. In accordance with an aspect of the present disclosure, the elongate-member width and the vortex-generator length comprise a ratio in a range of about 1.5:1 to about 0.25:1. For example, if the elongate-member width is about 5 mm, then the vortex-generator length might be in a range of about 6.25 mm to about 7.5 mm, which would provide a ratio in a range of about 0.8:1 to about 0.66:1—and the vortex-generator length might be smaller or larger and still fall within the described ratio. In a further example, if the vortex-generator length is about 7.5 mm, then the elongate-member width might be in a range of about 1.125 cm to about 1.875 mm. These are merely exemplary of some aspects of the disclosure, and in other aspects, the ratio of dimensions within the vortex-generator device may fall outside of this ratio. 
     As mentioned above, a vortex generator includes a vortex-generator height, which defines how far the vortex generator protrudes from the article surface. The dart-shaped vortex generators include a height, which is maximum at the trailing edge, and any alternative vortex-generator configuration or shape would similarly include a vortex-generator height, which may be at the trailing edge or at any other portion of the vortex generator. In an aspect of the present invention, the vortex-generator height it is a range of about 2 mm to about 6 mm. 
     A vortex-generator device includes other features. For example, in  FIGS. 1A and 2A-2C , the elongate members form a grid structure, or lattice structure, in which each elongate member intersects with another elongate member at a vertex to form an angle. In addition, the lattice structures of  FIGS. 1A and 2A-2C  arrange the vortex generators in a matrix, in which each vortex generator is positioned near a respective vertex. A vortex-generator device might include other configurations, as well. For example,  FIG. 3  depicts an exemplary vortex-generator device  312  in which at least some of the elongate members (e.g.,  314 A and  314 B) are collinear with one another. In addition, the vortex-generator device  312  includes a plurality of different arms  315 A- 315 E that arrange the vortex generators in a matrix. Thus, even though the configuration of the elongate members is different between the vortex-generator devices  12  and  312 , the matrix arrangement of the vortex generators is similar (e.g., spacing, density, pattern, etc.). 
     A configuration of the elongate members (e.g., lattice, discrete arms, etc.) might be selected to affect the underlying article in different manners. For instance, the discrete arms  315 A,  315 B, and  315 C might reduce stretch (and increase compression) by a lesser extent than if the arms  315 A,  315 B, and  315 C were interconnected at each vortex generator. In a further aspect of the present disclosure, the vortex-generator device  312  includes multiple regions  321  and  323 , and each region includes a respective set of properties. For example, both regions  321  and  323  include a similar matrix of vortex generators, but the region  321  might reduce stretch of an underlying article more than the region  323 . 
       FIG. 1A  depicts the article  10  as an upper-body garment, and the vortex-generator device is coupled to a lateral abdominal region. Moreover, the trailing edges are arranged posteriorly, relative to the leading edge. And a vortex-generator device may be coupled to other articles as well. For example,  FIG. 4A  depicts a vortex-generator device  412 A coupled to a leg sleeve of a lower-body garment  410 A, such that the trailing edge is arrange posteriorly, relative to the leading edge. As another example,  FIG. 4B  depicts another vortex-generator device  412 B coupled to another type of sleeve  410 B, which might be an arm sleeve or a leg sleeve. 
     In addition to article of apparel or clothing accessories, a vortex-generator device might be coupled to other types of articles. Referring to  FIG. 5A , in one aspect of the present disclosure, a vortex-generator device  512  is coupled to an adhesive-tape strip  510 , which may be selectively and removably affixed (e.g., adhered) to another surface, such as a skin surface, garment surface, equipment surface, and the like. 
     The strip  510  includes an outward-facing surface  514 , which faces away from the surface to which the strip  510  may be removably affixed. The adhesive-tape strip  510  is constructed such that the vortex-generator device  512  is affixed to the outward-facing surface  514 .  FIG. 5B  depicts a cross-sectional, schematic view of the adhesive-tape strip  510 , taken across the cross-sectional reference line depicted in  FIG. 5A , in accordance with an aspect of the present invention. (The depiction provided by  FIG. 5B  is schematic in nature and is not necessarily meant to illustrate or depict accurate scaling of layer thickness or vortex-generator-device sizing or spacing). In  FIG. 5B , the adhesive-tape strip  510  includes the outward-facing surface  514  of a base-layer substrate layer  516 . The base-layer substrate  516  includes a tape material layer, such as a knit, woven, or non-woven textile. The tape material layer may be elastic (e.g., elastomeric and flexible fabric) configured to stretch uni-directionally (e.g., in length) or bi-directionally (e.g., length and width) to provide a desired force against an applied-to surface (e.g., an athlete&#39;s skin surface). In addition, the base-layer substrate  516  might be designed to provide a desirable amount of breathability and/or moisture tolerance. The base-layer substrate  516  might be constructed of a natural fiber (e.g., cotton), a synthetic fiber, or a combination thereof. In one aspect, the base-layer substrate  516  is a type of base-layer substrate used to construct elastic therapeutic tape (e.g., kinesio tape). 
     The adhesive-tape strip  510  also includes a first adhesive layer  518  applied to an inward-facing surface of the base-layer substrate  516 , the inward-facing surface generally opposing the outward-facing surface  514  and facing towards a surface to which the strip  510  is removably affixed. The first adhesive layer  518  might have various properties making the adhesive-tape strip  510  suitable for application to human skin in a therapeutic or supportive context, such as non-irritation properties, heat-activation properties, and the like. 
     In one aspect, the adhesive-tape strip  510  includes a removable backing layer  520  that covers the adhesive layer  518  prior to the strip  510  being applied to a surface. The removable backing layer  520  can then be peeled away from the strip  510  to uncover the adhesive layer  518 . However, in other aspects, the removable backing layer  520  might be omitted, and the strip  510  may be rolled up to cover the adhesive layer prior to applying the strip to a surface. 
     As described with respect to  FIGS. 1A-1C , the vortex-generator device  512  includes a plurality of vortex generators  522 ,  524 , and  526  that are interconnected by one or more elongate members  528  and  530 . Furthermore, the vortex-generator device  512  is affixed to the adhesive-tape strip  510  by a bonding layer  532 . 
     Vortex generators might be coupled to the one or more elongate members in various manners. For example, the vortex generators might be coupled to the elongate member, such as by bonding, ultrasonic welding, curing, and the like to an exterior surface (e.g., surface  34  in  FIG. 1B ). In other aspects, the vortex generators and the elongate members might be molded or 3D printed to include a unitary construction. Referring to  FIG. 6 , an illustrative depiction shows a vortex-generator device  112 , which includes a plurality of vortex generators  114 ,  116 ,  118 , and  120  that are interconnected by a grid of elongate members  122 ,  124 ,  126 , and  128 . Each of the vortex generators  114 ,  116 ,  118 , and  120  includes a respective base  130 ,  132 ,  134 , and  136 . As depicted, the vortex-generator bases  130 - 136  extend beyond the footprint of the elongate members. As such, an underneath-side surface (e.g., surface  138  of vortex generator  114 ) might also be attachable to an article (in addition to the underneath-side surface of the elongate members), such as by the bonding layer  44  described with respect to  FIGS. 1B and 1C . Attachment of both the vortex-generator bases and the elongate members to the underlying article may provide additional stability to the vortex-generator device  112 . Further, in accordance with aspects depicted in  FIG. 6 , one of the elongate members (e.g., the elongate member  122 ) is directly connected to at least one neighboring elongate member (e.g., the elongate member  126 ). In an additional aspect, an opening is formed between the elongate member (e.g., the elongate member  122 ) and the at least one neighboring elongate member (e.g., the elongate member  126 ). 
     In one aspect of the present disclosure, the vortex generators  114 - 120  and the elongate members  122 - 128  are integrally molded from a same material, which might include a polyurethane (PU), a silicone-rubber composition, or some other elastomeric polymer. In other instances, the vortex-generators  114 - 120  and the elongate members  122 - 128  might be co-molded (e.g., in a two-step process) from the different materials to achieve different sets of material properties. In each of these instances, a unitary construction may be achieved by molding both the vortex generators and the elongate members together. Among other things, a unitary construction may improve an interface  140  between the vortex generator  114  and the elongate member  126 , such that the interface  140  is stronger and less susceptible to disconnecting or tearing (as compared to constructing the vortex generators separately from the elongate members and affixing the two parts together with another coupling mechanism). 
     Referring now to  FIG. 7  a method  710  of manufacturing an article having a vortex-generator device will now be described. At step  712 , a vortex-generator-device mold is filled with an elastomeric composition in a first state. For example, the mold might be filled with a silicon-rubber composition in an uncured state. In addition, the mold might include a plurality of vortex-generator-shaped depressions or cavities having a first depth and one or more grooves connecting the vortex-generator shaped depressions to one another. The one or more grooves include a second depth that is less than the first depth, the second depth being measured from a mouth or opening of the groove to a base of the groove. Step  714  includes curing the elastomeric composition to a second state while the elastomeric composition is in the vortex-generator-device mold, the elastomeric composition forming a vortex-generator device when cured. In addition, step  716  includes applying a bonding agent to a surface of the vortex-generator device, the surface positioned at a mouth of the one or more grooves, and step  718  includes curing the bonding agent while the vortex-generator device is in the vortex-generator-device mold. 
     At step  720 , the vortex-generator device is transferred to a jig (also referred to as a carrier block). The jig includes cavity shapes that are complementary to the vortex-generator device, such that the vortex-generator device nests upside down in the jig with the surface having the bonding agent is exposed. In some aspects, a transfer sheet might be affixed to the bonding layer of the vortex-generator device after the bonding agent is cured and before the vortex-generator device is transferred to the jig. And in other aspects, the vortex-generator device might be transferred to the jig without applying any transfer sheet to the bonding agent. An exemplary jig  810  is illustrated in  FIG. 8 , which depicts bonding surface  812  of an exemplary vortex-generator device  814 . For illustrative purposes,  FIG. 8  omits portions of the vortex-generator device  814  that would be included inside the cutout portion  815  and that would otherwise obscure the complimentary portions  816 ,  818 , and  820  of the jig  810 . The complimentary portions  816  and  818  include vortex-generator-shaped depressions or cavities having a first depth, and the complimentary portion  820  includes a groove connecting the vortex-generator shaped depressions to one another. The one or more grooves may include a second depth that is less than the first depth, and in this sense, the jig  810  may share some similar dimensions with the mold. The portions  816 ,  818 , and  820  are configured to seat complimentary portions of vortex generators and elongate members, respectively, for attachment to an article. 
     Step  722  includes applying a material layer (e.g., material layer of article of apparel or material layer of adhesive-tape strip) to the surface with the bonding agent, while the vortex-generator device is in the jig. If a transfer sheet was applied, then the transfer sheet is removed prior to applying the textile layer. At step  724 , the bonding agent is activated (e.g., heat, pressure, UV, etc.) to couple the vortex-generator device to the material layer. 
     From the foregoing, it will be seen that this subject matter is adapted to attain ends and objects hereinabove set forth together with other advantages, which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Since many possible variations and alternatives may be made of the subject matter without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.