Talk:Constructal theory

Could someone with a more in-depth understanding of the domains at work here include some more detailed examples? The current text gives the flavor of what I envision this to be, but I still don't really understand it. Skorgu 22:40, 9 February 2006 (UTC)

It's easiest to see with a car or an animal. Let's take a ford car. When ford design a car, they don't always know how heavy/strong the car needs to be to survive in the real world that their customers drive in. So they build it. And in some cases they make mistakes, and bits break more often than they should, so they redesign them. So they have a car that works. However it doesn't stop there (not always), often Ford want to make the car lighter since then it accelerates faster, and by using less materials in making the car, they can make it cheaper, which increases their profit. So they have been known to take a car apart after a hundred thousand miles and find out which bits haven't worn at all, and deliberately make them more cheaply.

So, the end result is an imperfect car, a car that more or less falls apart simultaneously. So, the car is equally imperfect; and this is an optimum design for a car.

In some cases you are able to describe this mathematically; and that allows you to know things about a situation without actually designing the car (or equivalent), or actually tells you stuff about what an optimum car design/shape is that lets you design it.

Hope this helps.WolfKeeper 02:37, 16 February 2006 (UTC)

I have read about constructal theory a few years ago and this is what I have understood to be its main principle: you first optimize the smallest components of a system, then you optimize their arrangement into the system. Thus, for a living organism, the cells must be optimized firstly, then their arrangement into tissues and then the tissues' arrangement in the whole body. The result would be a thoroughly optimized organism. Ferred 10:01, 28 July 2007 (UTC)

Actually, that would be the method of applying constructal theory in engineering. The principle appears in the text: allowing currents to flow easier from source to sink. The diffrerent patterns obtained depend on the geometry of the source and the sink (point, linear, surface, volume sources and sinks) and from the dual nature of the medium between them: there may be a "porous" medium with very little flow or there may be a "channel" with very high flow. In nature, "channels" appear in the "porous" medium due to the tendency of flow to occur with less resistance. Ferred 10:56, 17 August 2007 (UTC)

Is the table under "Principles" is plagiarized from http://www.constructal.org/en/theory/presentation.html (or the other way around?) 24.110.186.216 (talk) 14:48, 28 December 2009 (UTC)

related pages?

this sounds similiar to Stuart_Kauffman's and others in the field of Complex_systems ideas about the role of Self-organization in evolution and biology, and Ilya_Prigogine's ideas on Dissipative_structures in Non-equilibrium_thermodynamics. Kevin Baas^talk 17:16, 12 January 2011 (UTC)

The biology parts (relationship of animal size to metabolism) also have a direct relationship to work that came out of the Santa Fe institute by Geoffrey West http://biology.unm.edu/jhbrown/Documents/Publications/West&Brown2004PT.pdf

Don't believe it

Wikipedia is an encyclopedia. As such it is purely descriptive. Thanks to wikipedia I now know what constructal theory claims to be. However my problem is that I just don't believe this principle is valid. It doesn't seem to work even in fluid dynamics which the language suggests should be the field it most directly applies to.

Consider a simple case of a fluid flowing through a pipe. Constructal theory would suggest that the fluid should organise its flow in a fashion to optimize throughput. OK - the water flows through the pipe. But now start increasing the pressure difference across the pipe. The flow rate will increase for a while, but at a certain pressure the flow rate will suddenly and drastically decline. This point is called the onset of turbulence. Once turbulence ensues the flow pattern becomes chaotic and the pipe is able to sustain only a much reduced rate of flow. This change happens spontaneously and seems to violate the constructal law.

Or consider meanders in river systems. If the objective is to maximise flow then a nice straight channel would seem to be the ticket. But straight channels are unstable and a river will instead carve out a pattern of meanders which are highly inefficient in terms of maximising throughput.

So is this a problem for Wikipedia? Not necessarily. An encyclopedia isn't an arbiter of correctness, for example the Flat Earth theory has a page. However perhaps my understanding of the law obtained by reading the main page is deficient, in which case a better explanation might be required. If my understanding is correct then in my opinion the constructal law is absolute twaddle. Hawthorn (talk) —Preceding undated comment added 02:01, 28 March 2012 (UTC).

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I think that point of view is crucial when considering this so-called law. In the statement of such a problem, it seems that the fluid dynamics should be defined in such a way that maximizes the flow of the fluid through the pipe. However, this implies that such dynamics could be defined from an isolated case and configuration: in other situations, the turbulence phenomenon could be different, or simply not exist. The definition of fluid turbulence should not depend on the configuration over which it is applied (although, speaking about fluid dynamics involves making the assertion that the medium is continuous, but let's assume that this problem verifies this hypothesis). Bejan states that turbulence appears through the maximization of the momentum flow. This is quite different.

Following the idea on the maximization of the pipe throughput, it could be argued that this sudden drop in flow after the onset of turbulence results from the assumption of the fluid's inability to change its environment. The fluid does not control its flow configuration through this pipe enough to avoid this throughput drop. From there, the constructal law does not state anything about any response from the fluid, because the hypothesis of flow configuration control is not verified. If, however, the fluid could modify the pipe section or any other property granting it a better flow, then (in principle) the constructal law should hold. It could be noted though that the presence or absence of turbulence should not be something over which the flow has any kind of control, at least directly.

This is how I understand it. However this is a theory and seems (to the best of my knowledge) to be only verified (but not proven mathematically). I agree that constructal theory might yet remain to be refuted in the future. Stating it as a 'law' is anyway very controversial for many reasons, and its foundations are quite vague. Bserenity, January 31, 2019, 01:04 (UTC+2)

Proposed merger from Page1

I suggest that this page and the Maximum power principle page are merged into a larger page on the topic.

On the suggestion to merge the Constructal Law and the maximum power “principle”

To merge the Wikipedia’s entry on Constructal Law with the entry on “Maximum Power” would be inappropriate because the Constructal Law is a law of physics, while “Maximum Power” is not a principle:

1. “Maximum Power” was discredited on irrefutable thermodynamics grounds by the well known MIT thermodynamics professor Elias Gyftopoulos . There is no evidence of “maximum power” design anywhere.
2. The maximization of power output per unit of fuel or food consumed is entirely different concept. It is an optimality statement known in biology and engineering as Entropy Generation Minimization (EGM), (e.g.,).

EGM is one of more than 10 statements of optimality (static, end design, destiny), which, at best, have local (ad hoc) applicability, and which contradict other ad hoc statements such as maximum entropy production. The growing literature shows that the evolutionary design phenomenon summarized as the Constructal Law accounts for all the ad hoc and contradictory statements that are in use, for example, minimum flow resistance versus maximum flow resistance. This why the Constructal Law is a law of physics, the law of evolutionary design in nature. For a review of this unification, see: Mre env (talk) 01:49, 7 March 2013 (UTC)