Constructal Theory: From Engineering to Physics, and How Flow Systems Develop Shape and Structure

Reis, A. Heitor

doi:10.1115/1.2204075

Cited by 240 publications

(107 citation statements)

References 86 publications

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“…2). This prediction is in accord with the constructal law [1][2][3][4] and also in accord with observations. In this way, the constructal law accounts for the origin of the spontaneous hierarchy among celestial bodies.…”

Section: Discussionsupporting

confidence: 78%

“…To the animate and inanimate examples (animal locomotion, river basins, turbulence) that were unified as a phenomenon of free-morphing flow design for greater access over time, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] we are now adding examples that belonged traditionally to solid mechanics. For example, the natural occurrence of hexagonal basalt columns is attributed to a principle of maximum energy release.…”

Section: Introductionmentioning

confidence: 99%

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The physics origin of the hierarchy of bodies in space

Bejan

Wagstaff

2016

Journal of Applied Physics

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The physical origin of torque and of the rotational second law Am. J. Phys. 83, 121 (2015); 10.1119/1.4896574Rotating frame analysis of rigid body dynamics in space phasor variables Am. J. Phys. 81, 518 (2013) Here we show that bodies of the same size suspended uniformly in space constitute a system (a "suspension") in a state of uniform volumetric tension because of mass-to-mass forces of attraction. The system "snaps" hierarchically, and evolves faster to a state of reduced tension when the bodies coalesce spontaneously nonuniformly, i.e., hierarchically, into few large and many small bodies suspended in the same space. Hierarchy, not uniformity, is the design that emerges, and it is in accord with the constructal law. The implications of this principle of physics in natural organization and evolution are discussed. V C 2016 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4941986] INTRODUCTIONRecent progress on the physics basis of evolutionary organization in nature 1,2 continues to bring together phenomena that were previously considered unrelated. To the animate and inanimate examples (animal locomotion, river basins, turbulence) that were unified as a phenomenon of free-morphing flow design for greater access over time, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] we are now adding examples that belonged traditionally to solid mechanics. For example, the natural occurrence of hexagonal basalt columns is attributed to a principle of maximum energy release. 19 The occurrence of cracks in solids is based on the same principle. [20][21][22] Soil cracking under the drying wind was explained as a phenomenon of evolutionary design that enhances mass flow and accelerates drying. 23 The aggregation of dust particles into clusters and dendrites was shown to be the result of the same tendency, to relieve electrostatic forces of attraction faster, through the evolutionary design of configuration. 24 Here we add to this growing list of evolutionary phenomena the natural occurrence of multi-size hierarchy of bodies suspended in space. The hierarchy of sizes is researched intensely and described regularly in planetary science and astrophysics. [25][26][27][28][29][30][31] Hierarchy emerges in two ways, through accretion (coalescence) and fragmentation resulting from collisions. Viewed from thermodynamics, 32 the system of bodies in space is in a state of internal tension because of gravitational attraction between neighboring bodies. This system "snaps" freely by flowing internally and changing its configuration. Bodies coalesce into larger bodies, and their collision (with fragmentation) dissipates the tension and resulting kinetic energy, en route to reduced body-body attraction throughout the system. This phenomenon has been studied in celestial mechanics under several scenarios, [25][26][27] and is recognized as the basis for the formation process of planets and the asteroid belt.Sizes increase over all scales through accretion. 31 Yet, the natural phenomenon is not only the growth of the body size...

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Section: Discussionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

The physics origin of the hierarchy of bodies in space

Bejan

Wagstaff

2016

Journal of Applied Physics

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“…It also aims to describe the evolution steps in natural process, and attribute the design processes to the dominion of physics [54]. Designs have the universal tendency to evolve in a certain direction in time [55].…”

Section: Constructal Lawmentioning

confidence: 99%

A response to industrial maturity and energetic issues: a possible solution based on constructal law

Trancossi

2015

Eur. Transp. Res. Rev.

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Purpose Transport vehicle industry is suffering a diffused technological maturity. Energy efficiency is increasing with a certain velocity. But many factors in car development are playing against. Method A critical literature review about technological maturity symptoms and industrial grade design methods is presented for the current research paper. In particular Multidisciplinary Design Optimization and Modular System Design has been considered. A technical and scientific discussion, is performed focusing on the technological effect they are generating. Results A possible answer comes from the MAAT 7th framework Program which defined a novel design method initially conceived for airships. It has been defined CDE, Constructal Design for Efficiency. It is specifically based on Constructal law and second Principle of Thermodynamics and aims to produce an original methodological synthesis of Modular Design principles and Multidisciplinary Optimization harmonizing them by thermodynamic principles. The result of this process allows tuning CDE on the road through an effective generalization of the preliminary CDE concept. The schematization of the necessary design process of a vehicle has presented and discussed.

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“…In such a tree the same pressure drop occurs at level of branching (see Reis, 2006). In this way, by using Eqs.…”

Section: Microcirculation and Starling Forcesmentioning

confidence: 99%

Heart rate, arterial distensibility, and optimal performance of the arterial tree

Silva

Reis

2014

Journal of Biomechanics

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a b s t r a c tIn this study we explore the ability of a previously developed model of pulsatile flow for explaining the observed reduction of arterial distensibility with heart rate. The parameters relevant for the analysis are arterial wall distensibility together with permeability and reflection coefficients of the end capillaries. A non-specific artery and the ensemble of tissues supplied by that artery were considered in the model. The blood current within that artery was equalized to the sum of all micro currents in the tissues supplied by that artery. A formula emerged that relates changes in arterial distensibility with heart rate, and also with some particular aspects of microcirculation. Then, that formula was tested with data of distensibilities of the radial and carotid arteries observed at the heart rates of 63, 90, and 110 b.p.m. The formula correctly predicted the trend of decreased distensibility with heart rate for both arteries. Moreover, due to the fact that the carotid artery supplies the brain, and because the Blood-Brain barrier is highly restrictive to colloids in the blood, for the carotid artery the formula predicted a less marked decrease in distensibility than in the case of the radial artery feeding muscle tissue, which has a greater permeability to colloids, a trend that was confirmed by data. It was found that reduction of arterial distensibility with heart rate was greater in arteries that supply end capillaries with high permeability and low reflection coefficients.

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Constructal Theory: From Engineering to Physics, and How Flow Systems Develop Shape and Structure

Abstract: Constructal theory and its applications to various fields ranging from engineering to

Cited by 240 publications

References 86 publications

The physics origin of the hierarchy of bodies in space

The physics origin of the hierarchy of bodies in space

A response to industrial maturity and energetic issues: a possible solution based on constructal law

Heart rate, arterial distensibility, and optimal performance of the arterial tree

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