Aerodynamics of the Sharks Surface - Essay Example

Aerodynamics of the Shark’s Skin Name Student Number Institution Course Code Instructor Date Aerodynamics of the Shark’s Skin Increased efforts have been observed in the aerodynamics engineering with respect to creating more effective and efficient aircrafts. The need for fast and fuel efficient models have seen increased studies on the dynamics and amazing features observed in various biological creatures and their adaptation to locomotion. This review evaluates the concept of shark skin effect and their organised pattern orientation on the surface that gives a resultant drag reduction effect. The review critically analyses various concepts surrounding the shark skins and their denticle features to form riblets. Finally, a brief review to the scanning electron microscope will be conducted. Sharks are very fast swimmers due to their well organised patterns on the surfaces of their skins. They have been shown to possess amazing, and excellent skins regarding their performance due to the drag reduction in what is termed as shark skin effect [1]. The skin mainly composes of scales that are tiny in size giving the roughness covering the skin of fast moving sharks and are shaped in the form of riblets perfectly arranged along the direction of the fluid flow [2]. The arrangement gives the ability to reduce the friction force and drag resistance enabling the animals to swim swiftly and fast in the water bodies. Sharks have specially formed skins that secrete mucus coupled a rough surface arranged systematically to reduce drag as they swim through water, while at the same time defending the animal from abrasion by making it slide across objects rather than scrape [1]. Nature is phenomenal and has created ways of minimising drag in fluid flow which is evident among sharks just like other fishes [3]. This aspect has been keenly studied by various fields with the aim of applying the same mechanism to reduce drag in fluids; water and gas. Turbulence occurring in a majority of fast flowing systems result in friction resistance and hence, effective biological aspects are found among best swimmers to overcome the drag [4]. The attributes appear fascinating with scientists and engineers embracing it to try and establish it application in the artificial manipulation of material surfaces to enhance movement. Surfaces with perfect structures in line with the flow direction form of riblets and dimensions that are suitable, and reduction of wall shear stress is achieved [5]. Riblets are not specific in their functioning be it in gaseous or liquid state, but their effectiveness is dependent upon the type of drag in existence. In aerodynamics, the existing drags involve skin friction, form, induced and wave. The induced drag comes about when the flow in line with the object is redirected and comes about due to the lifting of aeroplane wings [6]. The wave drag involves shock wave formation in front of an object that moves at transonic and supersonic speeds, whereas the form drug also termed as pressure drag is dependent upon the shape of the object [6]. For objects having a high cross section with respect to their length has more form of drags than objects having a small cross section. The skin friction drag involves a type of drag occurring due to the interaction of the fluid with the wall of an object and can be reduced effectively by use of riblets [7]. Skin friction can be increasingly reduced as a form of drag by use of riblets. Thus, it is only for objects having a high proportion of skin friction where riblets find relevance making their utilisation in aerodynamics very critical. Aeroplanes and ships have a high fraction of skin friction thus; the technology behind the shark skin effect finds relevance for utilisation to improve their speed [2, 5]. According to Lang et al. [5], in the event that a surface is structured with the most favourable riblets having the right dimensions, the result is a significant reduction of the skin friction by 10%. This occurs due to the riblets being along the direction of flow. Sharks have skins developed biologically with a roughness that is termed sandpaper-like by many people [1]. There are more than 400 species of sharks with their skin being covered by a matrix of tiny, hard and tooth-like features termed as the dermal denticles [6, 8]. The scales are very useful during swimming due to their orientation in curved and grooved shapes that make the skin have a rough texture. Sharp scales on fast swimming sharks have been indicated by researchers to move at angles exceeding 50o [1]. This orientation has been premised by various engineers and researchers to give sharks the characteristic effective flow in the preferred direction. Scientists and engineers have been fascinated and attracted by the shark skin concept with the main aim of identifying realisation of saving fuel use in the aviation industry. A good example is Airbus industry that has embraced the construction of aircraft based on the concept of the groovy skin of a shark to reduce and drag effect [9]. This is mainly based on the fact that, just like the sharks reduces energy consumption in their swimming, utilising the shark skin effect in the aviation sector will result in the utilisation of less energy. The global aviation industry is of late dominated with finding technologies that would result into efficient aircrafts using less fuel and contribute towards reducing energy consumption and global warming [9]. Various works of literature have evaluated the shark skin effect resulting to increased industrial and manufacturing sector exploiting the concept in respect to swimming and flying stud tests. It has been argued by Cutkosky and Kim [4] that, by utilising the directional super-adhesive surfaces among legs of robots would result into a robot that can climb walls in the same manner as a gecko. The production of swimsuits was modified, but there have been great controversies on the advantage and effectiveness of the swimsuits in enhancing speed. According to Sanders et al. [8], improvement of new swimsuits was minimal and was not coming from the reduction of friction concept. Successful application of riblets in water involves the production boats and ships hulls where the drag reduction concept has been applied. The concept of riblets use in a ship was imperative not only in the reduction of drag and increase speed, but also resulted to less energy usage while crossing the sea [10]. Oeffner and Lauder [10] indicates that by utilizing the concept of shark skin effect, accurate determination of self-propelled swimming speed for both rigid and dynamic membrane like surfaces have been studies to establish the effect of riblet on locomotion. By studying the sharks, artificial modification of surfaces has been effectively evaluated with the like of silicone riblets on the surface of swimsuits to enhance swimming speed. Nevertheless, Oeffner and Lauder [10] found no consistent increase in the swimming speed in respect to the same skin without the denticles. Wen et al. [1] indicates the need for increased analysis of the concept of shark skin effect due to lack of conclusive findings on the aspect. The researchers indicate that the ability to fabricate synthetic shark skin enhances various ways of possible manipulations that can be utilized to examine the hydrodynamics results of diverse skin denticle shapes as evidenced by various species of shark skins. Cheng et al. [3] on the other hand evaluate the use of coating technology to come up with a bio-replica of the shark skin effect utilizing the UV curable paint. The study established increased efficiency with 12% higher and anti-fouling being proved in respect to drug reduction. The Scanning Electronic Microscope (SEM) The scanning electron microscope (SEM) is crucial in high resolution imaging, and utilises a focused beam of electrons instead of light to scan over a specific surface and give an image for detailed analysis [11]. The electrons within the beam interact with the sample under analysis giving out a number of signals that are utilised to acquire information pertaining to the surface topography and composition of the sample. According to a study carried in 2011 [12] the SEM instrument can be utilised to analyse biological samples and acquire three-dimensional images. This technique is very crucial in analysing image volumes utilising the isotropic voxels. The SEM as an instrument produces a beam of electrons instead of light to create an image [13]. The beam of electors is produced at the top of the microscope via an electronic gun which directs to follow a vertical route via the microscope contained within a vacuum. Then, the beam travels via electromagnetic fields and lenses lined up in the path for focussing the beam towards the exact position of the sample [12]. Upon the beam of electron hitting the sample under analysis, emission of electrons and X-rays occurs from the sample. All the components at this stage; X-rays, dispersed electrons and secondary electrons are then collected by detectors and converted into signals which are later sent to the screen for illumination to give a final image [13]. Experiments involving SEM requires special arrangements due to the fact that vacuum conditions are required together with electrons to give out an image [12]. The sample must be water free and covered with a conductive layer through the introduction of a sputter coater which can be achieved by utilising an electric field and argon gas [11]. The final image involves signals that reveal crucial details incorporating the external morphology, chemical composition and crystalline structure as well as the orientation of the materials that make up the sample [14]. Reference List 1. Wen, L., Weaver, J. and Lauder, G., 2014. Biometric Shark Skin: Design, Fabrication and Hydrodynamic function. The Journal of experimental Biology 217 (2014) 1656-1666. 2. Dean, B. and Bhushan, B., Shark-Skin Surfaces for Fluid-Drag Reduction in Turbulent Flow: A review. Philosophical Transactions of the Society A 368 (2010) 4775-4806. 3. Chen, H., Zhang, X., Ma, L., Che, D., Zhang, D. and Sudarshan, T. Investigation on Large-Area Fabrication of Vivid Shark Skin with Superior Surface Functions. Applied Surface Science 316 (2014) 124-131. 4. Cutkosky, M.R. and Kim, S., Design and Fabrication of Multi-Material structures for Bioinspired Robots. Phil. Trans. R. Scoc. A 367 (2009) 1799-1813. 5. Lang, A., Bradshaw, M., Smith, J., Wheelus, J., Motta, P., Habegger, M. and Hueter, R., Movable Shark Scales act as a Passive Dynamic Micro-Roughness to Control Flow Separation. Bioinspiration and Biomimetics 9 (2014) 3. 6. Lang, A., Motta, P., Hueter, R., Habegger, M. and Afroz, F., 2011. Sharp Skin Separation Control Mechanisms. Marine Tech. Soc. J. Vol. 45, no. 4, pp. 208-215. 7. Houghton, E.L. and Carpenter, P.W., 2003. Aerodynamics for Engineering Students. Elsevier Butterworth Heinemann. 8. Sanders, R., Rushall, B., Toussaint, H., Stager, J. and Takagi, H., Bodysuit Yourself: But First Think About It. Swimming Science Journal 1 (2001). 9. Balmer, E. Aviation Industry Dons ‘Shark Skins’ to Save Fuel. Phys Org (2013) . 10. Oeffner, J. and Lauder, G.V. The Hydrodynamic Function of Shark Skin and Two Biomimetic Applications. The Journal of experimental Biology 215 (2012) 785-795. 11. Bogner, A., Jouneau, P.H., Thollet, G., Basset, D. and Gauthier, C., A History of Scanning Electron Microscopy developments: towards “wet-STEM” Imaging. Micron. 38 (2006.) 390-401. 12. Knott, G., Rosset, S. and Cantoni, M., Focused Ion Beam Milling and Scanning Electron Microscope of Brain Tissue. J Vis Exp. 53 (2011) 2588. 13. Purdue University, Scanning Electron Microscope. Radiological and Environmental Management, Purdue University (2014) . 14. Swapp, S. Scanning Electron Microscopy (SEM): What is Scanning Electron Microscopy (SEM) Geochemical Instrumentation and Analysis (2015) Accessed . Read More