Half a croissant, on a plate, with a sign in front of it saying '50c'
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Evolutionary Streamlining Arrangements

matter accumulates in turbulent areas
  [vote for,

The theory of evolution, developed by Charles Darwin, and the phrase coined by Herbert Spencer, “survival of the fittest”, are not only applicable to biology, but also to devices created by humankind. Means of transport, engines that propel them, and power generating machinery are very good examples, they have come a long way from their beginnings. Hydro- and aerodynamically streamlining played an important part in their evolution.

One can observe that matter accumulates in turbulent areas of objects; and turbulence-causing features on objects erode, if exposed to a flow of erosive fluid. A streamlining arrangement may employ these phenomena and facilitate the streamlining of fluid-dynamically challenged objects by exposing them to flowing fluids, and allowing, and/or causing the fluids, and/or matter, which may be suspended and/or dissolved in the fluids, to accumulate and/or adhere to the objects, and/or erode matter from the objects. Adherence and/or erosion of matter may be caused by physical and/or chemical means. The link lower down leads to more details and examples.

Special characteristics of such arrangements may include, that they allow the streamlining of internal features of objects, for example inlet and outlet ports of a cylinder head and its manifolds, and that they allow an object to be dynamic during a streamlining process, for example a fan or propeller may be rotating.

Arrangements like these may be of use in the design, development, and manufacture, of fluid-dynamically challenged objects such as cars, aircrafts, ships, propellers, fans, turbine blades, turbine housings, impellers, nozzles, fluid intake and exhaust systems, and other objects, which benefit from a streamline shape. They may also help to better understand the nature of real-life, three-dimensional turbulence, which still is largely unexplained.

(English is my second language, please be tolerant in regard of spelling and grammatical errors. Corrections and suggestions are welcome.)

fh, Jun 17 2004

Streamlining Arrangement http://www.oocities...gement/sa_ppat.html
some more details [fh, Oct 04 2004, last modified Jan 01 2014]


       Your standard of English is well above that of many contributors to this site. This idea might be better implemented in computer software however, as a sort of active or adaptive wind tunnel test. The downside to a software version would be, as you say, the requirement for a good understanding of turbulence first.   

       <edit> fh's link suggests exactly this. Bun.
david_scothern, Jun 17 2004

       Your English is far better than mine, and it's my first language. My second language is Queen's English, which I still manage to speak with an American accent.   

       I think I like this and/or will give you a croissant.
shapu, Jun 17 2004

       The idea sounds reasonable, but it seems to be based on the premise that objects will naturally take an ideal shape when exposed to the right medium. This premise may be correct in some situations but not in others.   

       Take for instance a raindrop. The common misconception is that they are tear-drop shapped as they fall, since this is the ideal aerodynamic shape. In reality, they form very unaerodynamic shapes as they fall.   

       Nature has no incentive to create shapes that we consider to be efficient. Consider a river rock. It gets rounded off at all the sharp corners. But it seems to me that nature may be optimising the surface area rather than the coeficient of drag. How do you tell the water that "You know... low surface area is nice, but today I'd like you to focus on optimizing the coefficient of drag." Actually you can probably affect that somewhat by using different abrassives, adhesives, etc as you describe, but I'm not sure there would be any combination that would get the result that you're looking for.   

       This could definitely be an interesting area of study, though it seems quite likely that it has already been studied way beyond the depth of our discussion here.
scad mientist, Jun 17 2004

       [Xclamp] I am sorry for taking so long to respond to your post.   

       Some high performance combustion engines do have variable intake and/or exhaust systems. I would believe that vascular systems in young creatures are also variable, i.e. the area of the cross-section may be flexible and adaptable, however, as aging takes its toll that feature may fade.   

       Could it be that the non-streamlining adherence and erosion in vascular systems you are referring to, is caused by turbulence? When a flow of fluid changes direction, velocities change within the flow of fluid. The differences in velocities may be responsible for change of pressures and the turbulence I am referring to. I did consider that with figure 4d in the more detailed description provided with the link. Looking at it, one may notice that the middle section of the duct is narrower than the entry and exit sections. The middle section may have an elliptical cross section.   

       As to the difference of the computer modelling done now to design a component's shape, is that a computer program is only as good as it’s creator and operator, whereas the methods described herein, with the exception of the Computing Method, apply the laws of fluid dynamics directly. The question “… and how are material and finish of the machined component accounted for in your model?” I do not understand, can you please elaborate on it?
fh, Jun 18 2004

       Perfectly aerodynamic car shapes would probably not be useable, you need to add various parts to the vehicle such as wing mirrors, the wheels need to be accesible there are variuos limitations on how close to perfectly aerodynamic you can get.
engineer1, Jun 18 2004

       [fh] sorry i accidentally deleted my annotation while trying to edit it for grammar! thanks for responding.   

       as you say, there is probably no single ideal design, only one that is ideal under a rigorously controlled set of parameters, which in short was the point of my line of questioning.   

       as for the vascular system, you are right that turbulence is responsible for non-streamlining erosion of the vasculature, particularly at the junction of an arterial branch, in fact figure 4d is precisely the shape of the renal artery as it takes off from the aorta after years of turbulence caused from hypertension, with a narrow lumen followed by an elliptical bend leading into the terminal segment. non-streamlining adherence (atherosclerosis) is thought to be the result of changes in viscosity and velocity of the blood as it flows through the system, which results in accumulation of particles in surface defects (see below*).   

       as for the material and finish of the machined component, i was assuming that different materials (such as plastic vs. metal) may have an effect on the flow of fluid or air across them either thru increased or decreased drag. by this i mean that *even small defects in the material or finish not visible to the eye may be sufficient over time to cause non-streamlining adherences. imagine even small pits in the finish that accumulate particles over time much in the same way a large crystalline structure might form over a single crystal given time.   

       also imagine the surface of a golf ball whose aerodynamic properties are enhanced not by changing its shape but by adding dimples to change the flow of air over its surface, which i suppose technically changes its shape, but in a different way than your method would.   

       these are just thoughts, again i think your idea is very good.   

       thanks again for reading.
xclamp, Jun 18 2004

       [Xclamp] the statement “An object to be streamlined may be exposed to an accumulating process, and an eroding process, simultaneously, or alternately” in the detailed description may be an answer for your question in regard of “the material and finish of the machined component”.
fh, Jun 18 2004

       So the idea is to make everything as energy efficient as possible?
phoenix, Jun 18 2004

       I read that the russians used analog computing to architect electrical grids; they literally created a physical fluid model of their electrical system, changed it around to adjust it, then did the physical part of building the changes
beanangel, Jan 16 2008


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