Adrian Bejan's Blog, page 5

Discrete Svelteness: Evaluating flow structures in generative constructal design

In this work, Matei C. Ignuta-Ciuncanu and Ricardo F. Martinez-Botas introduce discrete svelteness, a novel tool for modeling self-organization in generative design within the framework of constructal theory. The study shows how morphological freedom granted by generative methods improves efficiency in key flow problems originally addressed by constructal design: area-to-point, circle-to-point, and vascular (canopy-to-canopy) architectures.

In addition to enabling detailed, pointwise evaluation of geometric efficiency, discrete svelteness reveals how evolved flow configurations adapt locally to their environment—something traditional global metrics often overlook. By analyzing the spatial and statistical patterns of these structures, including power-law and skewed distributions, the study highlights how complexity, branching, and diversity emerge as signatures of efficient design.

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Special Issue in BioSystems

We are pleased to announce that selected papers from the Constructal Law Conference 2025 will be published in a Special Issue of BioSystems (Elsevier), which encourages theoretical, computational, and experimental articles that link biology, evolutionary concepts, and the information sciences. This Special Issue, titled "Constructal Law: Design in Nature and Society," is organized in collaboration with the International Academy of Information Studies (IAIS) and will feature research that applies Constructal Law to the analysis and design of flow systems across disciplines.

CONSTRUCTAL LAW CONFERENCE 2025

🗓️ 5-7 November 2025 Florida International University, Miami FL, USA

Deadlines for Constructal Law Conference 2025

Abstract Submission: May 15, 2025

Abstract Acceptance: May 31, 2025

Extended Abstract Submission: August 31, 2025

More details on the Special Issue

More details on the Constructal Law Conference 2025

Adrian Bejan | The power to predict, from Design in Nature

In this lecture, Adrian Bejan discusses the concept of design choices and architectures in nature, emphasizing that while designs may seem limitless, they are bounded by a realm of possible configurations. He introduces the idea that specific perfect designs exist, such as the round tube and regular hexagon, which represent ideal forms. Bejan explains how understanding these concepts allows one to predict future opportunities and innovate effectively, giving individuals a unique advantage in design.

Bejan explains that design choices, or architectures, are constrained by a specific realm of possible designs, indicating that not all designs are feasible. This space includes both perfect designs and those that are closer to perfection, which are easier to create.

He identifies certain perfect forms, such as the round tube and the regular hexagon, that serve as benchmarks. These perfect shapes represent the pinnacle of efficiency and effectiveness in design.

Bejan discusses how a population of 'good enough' designs exists near the ideal, which are often easier to invent and implement. These designs provide practical opportunities for innovation.

The ability to identify and anticipate opportunities within the design space gives students an edge. Bejan emphasizes that understanding these patterns allows one to predict outcomes before they occur, differentiating it from traditional methods of observation and explanation.

Adrian Bejan I The power to predict, from Design in Nature

In this lecture, Adrian Bejan discusses the concept of design choices and architectures in nature, emphasizing that while designs may seem limitless, they are bounded by a realm of possible configurations. He introduces the idea that specific perfect designs exist, such as the round tube and regular hexagon, which represent ideal forms. Bejan explains how understanding these concepts allows one to predict future opportunities and innovate effectively, giving individuals a unique advantage in design.

Bejan explains that design choices, or architectures, are constrained by a specific realm of possible designs, indicating that not all designs are feasible. This space includes both perfect designs and those that are closer to perfection, which are easier to create.

He identifies certain perfect forms, such as the round tube and the regular hexagon, that serve as benchmarks. These perfect shapes represent the pinnacle of efficiency and effectiveness in design.

Bejan discusses how a population of 'good enough' designs exists near the ideal, which are often easier to invent and implement. These designs provide practical opportunities for innovation.

The ability to identify and anticipate opportunities within the design space gives students an edge. Bejan emphasizes that understanding these patterns allows one to predict outcomes before they occur, differentiating it from traditional methods of observation and explanation.

Adrian Bejan | Lagrange & undetermined coefficients, from Design in Nature

In this lecture, Adrian Bejan discusses the relationship between pressure drop and mass flow rate in slender tubes, specifically focusing on minimizing flow resistance in laminar flow. He elaborates on Lagrange's method of undetermined coefficients to optimize the design of tubing configurations, dividing the analysis into manageable segments and yielding important ratios that define effective flow systems. The video also includes key historical references to mathematicians and their contributions to calculus, illustrating their work's relevance to modern fluid dynamics applications.

The objective of this discussion is to minimize flow resistance in laminar flow. Bejan describes how to factor out the mass flow rate from the pressure drop equations, focusing on minimizing the combined resistance terms from two tube configurations.

Bejan introduces Lagrange's method of undetermined coefficients as a simplification technique for solving optimization problems. He explains that by treating the lengths of tubes as known, the problem can be reduced to minimizing a function concerning tube diameters.

The lecture progresses to derive critical ratios for diameters (D1/D2) that minimize flow resistance using calculus, specifically discussing the results from the derivative calculations and their implications for tube design.

Throughout the lecture, Bejan references historical mathematicians like Lagrange and Euler, noting their contributions to calculus and their impact on modern engineering principles. This context emphasizes the collaboration and evolution of mathematical thinking.

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Umit Gunes, Ph.D.
Assoc. Prof., Yildiz Technical University
umitgunes.com

Adrian Bejan I Lagrange & undetermined coefficients, from Design in Nature

In this lecture, Adrian Bejan discusses the relationship between pressure drop and mass flow rate in slender tubes, specifically focusing on minimizing flow resistance in laminar flow. He elaborates on Lagrange's method of undetermined coefficients to optimize the design of tubing configurations, dividing the analysis into manageable segments and yielding important ratios that define effective flow systems. The video also includes key historical references to mathematicians and their contributions to calculus, illustrating their work's relevance to modern fluid dynamics applications.

The objective of this discussion is to minimize flow resistance in laminar flow. Bejan describes how to factor out the mass flow rate from the pressure drop equations, focusing on minimizing the combined resistance terms from two tube configurations.

Bejan introduces Lagrange's method of undetermined coefficients as a simplification technique for solving optimization problems. He explains that by treating the lengths of tubes as known, the problem can be reduced to minimizing a function concerning tube diameters.

The lecture progresses to derive critical ratios for diameters (D1/D2) that minimize flow resistance using calculus, specifically discussing the results from the derivative calculations and their implications for tube design.

Throughout the lecture, Bejan references historical mathematicians like Lagrange and Euler, noting their contributions to calculus and their impact on modern engineering principles. This context emphasizes the collaboration and evolution of mathematical thinking.

---
Umit Gunes, Ph.D.
Assoc. Prof., Yildiz Technical University
umitgunes.com

Experimental and numerical analysis of a novel constructal design for canopy-to-canopy liquid cooling systems

The cooling capacity of canopy-to-canopy flat plates with the coolant inlet and outlet on the same side of the plate was analyzed in detail, both experimentally and numerically. A novel constructal design was proposed to derive the diameter of each branch of canopy-to-canopy configurations. Thanks to the predicted diameter ratios, the new design results in a reduction of the coolant pumping power of 60 % to achieve the same maximum temperature as a traditional configuration with equal diameters in all branches. Four canopy-to-canopy configurations with a number of branches ranging from 2 to 5 were designed based on this innovative constructal approach to optimize the cooling capacity of flat plate systems, keeping the same fluid volume for all of them. The resulting designs were tested experimentally and modelled for steady state and transient cooling operations. A higher number of branches improved the steady state cooling performance under continuous heating, as the 5-branches configuration yielded the lowest maximum and mean temperatures while maintaining similar temperature homogeneity in both experimental measurements and numerical simulations. The maximum deviation between experimental and numerical results was 1.4 ◦C for both maximum and average temperatures, allowing the validation of the numerical models. For the transient cooling process, the flat plates experienced a progressively faster temperature reduction over time as the number of branches in the design increases, accelerating the cooling process by 14.7 % when increasing the number of branches from 2 to 5. The results show that the 5-branches canopy-to-canopy configuration has an excellent cooling capacity with a limited pressure drop to circulate the coolant.

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Adrian Bejan | How to make a drawing , from Design in Nature

Adrian Bejan discusses flow architectures, focusing on the transition from connecting points to connecting points with an infinity of locations, represented by tree-like structures in nature. He emphasizes the importance of understanding flow direction, the growth patterns in nature, and how to create drawings to visualize these concepts.

The direction of flow, whether inbound or outbound, is not crucial to the design challenge; the focus is on understanding and predicting flow architectures.

Observed flow architectures are often dendritic, seen in vascular design, and serve as a key example in discussing flow designs.

Creating a drawing requires understanding both external and internal size constraints and the aspect ratios that define the dynamic of flow architectures in nature.

Due to constraints on variable lengths and diameters, flow architectural design has two degrees of freedom, highlighting the balance between structure and design freedom.

The pressure drop across flow systems is crucial for understanding the dynamics of flow in various architectures. It illustrates the relationship between flow paths and their efficiencies.

Depending on its flow direction, the same flow architecture can be described in two ways: as bifurcating branches or tributaries feeding into a larger channel.

---
Umit Gunes, Ph.D.
Assoc. Prof., Yildiz Technical University
umitgunes.com

Adrian Bejan I How to make a drawing , from Design in Nature

Adrian Bejan discusses flow architectures, focusing on the transition from connecting points to connecting points with an infinity of locations, represented by tree-like structures in nature. He emphasizes the importance of understanding flow direction, the growth patterns in nature, and how to create drawings to visualize these concepts.

The direction of flow, whether inbound or outbound, is not crucial to the design challenge; the focus is on understanding and predicting flow architectures.

Observed flow architectures are often dendritic, seen in vascular design, and serve as a key example in discussing flow designs.

Creating a drawing requires understanding both external and internal size constraints and the aspect ratios that define the dynamic of flow architectures in nature.

Due to constraints on variable lengths and diameters, flow architectural design has two degrees of freedom, highlighting the balance between structure and design freedom.

The pressure drop across flow systems is crucial for understanding the dynamics of flow in various architectures. It illustrates the relationship between flow paths and their efficiencies.

Depending on its flow direction, the same flow architecture can be described in two ways: as bifurcating branches or tributaries feeding into a larger channel.

---
Umit Gunes, Ph.D.
Assoc. Prof., Yildiz Technical University
umitgunes.com

Adrian Bejan I Diversity, Bismarck & Civilization, from Design in Nature

In this video, Adrian Bejan discusses the concept of design in nature, exploring the configurations of systems that can move and evolve. He emphasizes the importance of diversity and innovation, linking it to historical references such as Bismarck's perspective on politics and how it reflects the desire to improve systems. He advocates for understanding designs' essence, evolution, and impact on civilization.

Design in Nature

Bejan introduces the concept of design in nature as the configurations of things that move, explaining that this concept covers everything in existence and correlates with evolution and design improvement.

Importance of Diversity

He discusses how variations in designs lead to diversity and presents this diversity as vital for progress, emphasizing that the essence of successful designs lies in their ability to adapt and improve.

Bismarck and Political Art

Referencing Otto von Bismarck, Bejan connects the concept of engineering designs to politics, suggesting that just as Bismarck worked to unify Germany, engineers strive to innovate and refine their designs for better functionality.

Politics as Civilization

Bejan challenges negative perceptions of politics by linking it to civilization, stating that politics historically represented the management and improvement of communities, akin to engineering.

Evolutionary Design

He highlights the role of engineers as constant innovators who seek to improve things. Bejan describes this as 'evolutionary design'—a relentless pursuit of improvement in system configurations.

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Umit Gunes, Ph.D.
Assoc. Prof., Yildiz Technical University
umitgunes.com