鲨鱼皮实际上会增加阻力
文章来源:未知 文章作者:enread 发布时间:2016-03-16 06:15 字体: [ ]  进入论坛
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On an intuitive level, you'd expect a shark's skin to reduce drag. After all, the purpose of sharkskin-inspired riblets -- the micro-grooved structures found in aircraft wings, wind turbine blades and Olympic-class swimsuits -- is to do just that. Sharkskin's ability to reduce hydrodynamic drag, however, has been academically contested for the past 30 years. To clarify this phenomenon, researchers at Stony1 Brook2 University and the University of Minnesota recently conducted simulations on the ability of the small, tooth-like denticles that make up sharkskin to modify hydrodynamic flow with an unprecedented3 level of resolution. Far from easing the glide4 through the water, they found, the structures can actually increase drag by up to 50 percent. 
 
Fotis Sotiropoulos -- whose previous work focused on developing computational tools to study the evolutionary5 impact of hydrodynamic factors on fish body shapes and swimming styles -- and his Ph.D. student Aaron Boomsma discuss their work exploring the hydrodynamics of sharkskin this week in Physics of Fluids, from AIP Publishing. 
 
"The work on sharkskin was a natural progression, especially after observing the commonalities between sharkskin and riblet films," said Sotiropoulos, dean of the College of Engineering and Applied6 Sciences at Stony Brook University and primary investigator7 of the project. "Our interest was piqued8 by the thought that sharkskin was capable of providing a hydrodynamic advantage to sharks." 
 
Sotiropoulos and his colleagues used experimental data about the three-dimensional geometry of shortfin mako shark denticles provided by George Lauder, a professor of organismic and evolutionary biology at Harvard University, to create computational beds of sharkskin denticles in aligned9 and staggered configurations10. They then applied numerical simulations based on immersed boundary concepts to study the details of turbulent water flow through and over the stationary11 denticle beds. 
 
"Our simulations show conclusively12, that for the tested configurations, sharkskin actually increases drag -- as high as fifty percent," Sotiropoulos said.


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1 stony qu1wX     
adj.石头的,多石头的,冷酷的,无情的
参考例句:
  • The ground is too dry and stony.这块地太干,而且布满了石头。
  • He listened to her story with a stony expression.他带着冷漠的表情听她讲经历。
2 brook PSIyg     
n.小河,溪;v.忍受,容让
参考例句:
  • In our room we could hear the murmur of a distant brook.在我们房间能听到远处小溪汩汩的流水声。
  • The brook trickled through the valley.小溪涓涓流过峡谷。
3 unprecedented 7gSyJ     
adj.无前例的,新奇的
参考例句:
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
4 glide 2gExT     
n./v.溜,滑行;(时间)消逝
参考例句:
  • We stood in silence watching the snake glide effortlessly.我们噤若寒蝉地站着,眼看那条蛇逍遥自在地游来游去。
  • So graceful was the ballerina that she just seemed to glide.那芭蕾舞女演员翩跹起舞,宛如滑翔。
5 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
6 applied Tz2zXA     
adj.应用的;v.应用,适用
参考例句:
  • She plans to take a course in applied linguistics.她打算学习应用语言学课程。
  • This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。
7 investigator zRQzo     
n.研究者,调查者,审查者
参考例句:
  • He was a special investigator for the FBI.他是联邦调查局的特别调查员。
  • The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。
8 piqued abe832d656a307cf9abb18f337accd25     
v.伤害…的自尊心( pique的过去式和过去分词 );激起(好奇心)
参考例句:
  • Their curiosity piqued, they stopped writing. 他们的好奇心被挑起,停下了手中的笔。 来自辞典例句
  • This phenomenon piqued Dr Morris' interest. 这一现象激起了莫里斯医生的兴趣。 来自辞典例句
9 aligned 165f93b99f87c219277d70d866425da6     
adj.对齐的,均衡的
参考例句:
  • Make sure the shelf is aligned with the top of the cupboard.务必使搁架与橱柜顶端对齐。
10 configurations 86f23519571eb918e8812e1979d55409     
n.[化学]结构( configuration的名词复数 );构造;(计算机的)配置;构形(原子在分子中的相对空间位置)
参考例句:
  • Such configurations, obtained theoretically by calculation, are called models of a star. 通过理论计算得到的恒星结构称为恒星模型。 来自辞典例句
  • The other two configurations have overriding advantages for special applications. 其它两种接法对特殊应用具有突出的优点。 来自辞典例句
11 stationary CuAwc     
adj.固定的,静止不动的
参考例句:
  • A stationary object is easy to be aimed at.一个静止不动的物体是容易瞄准的。
  • Wait until the bus is stationary before you get off.你要等公共汽车停稳了再下车。
12 conclusively NvVzwY     
adv.令人信服地,确凿地
参考例句:
  • All this proves conclusively that she couldn't have known the truth. 这一切无可置疑地证明她不可能知道真相。 来自《简明英汉词典》
  • From the facts,he was able to determine conclusively that the death was not a suicide. 根据这些事实他断定这起死亡事件并非自杀。 来自《简明英汉词典》
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