技術論文とプレゼンテーション

Fractal-like branching channel networks, inspired by the branching transport systems found in nature, like tree branches, offer a route to more compact and thermally efficient heat exchangers. However, their macro-scale design space is large and tightly constrained. The bifurcation angles, hydraulic-diameter ratios, length ratios and the number of branching levels interact strongly, and many parameter combinations produce geometrically invalid networks. Building and simulating each candidate design by hand is impractical, which has limited systematic exploration of these geometries. A fully parametric workflow was developed using LiveLink for MATLAB to automate the generation, meshing and simulation of diverging–converging fractal-like branching heat exchangers in COMSOL Multiphysics. A recursive MATLAB algorithm constructs a single-inlet, single-outlet branching channel network and a tight-fitting shell from a small set of physically meaningful inputs (trunk branch dimensions, branching level ( r = 0-6), and per-level bifurcation angle, hydraulic-diameter ratio and length ratio). Geometric feasibility rules are enforced prior to each simulation, checking junction coverage and connectivity of branches, branch overlap and self-intersection, monotonic bifurcation-angle ordering (θ3 < θ2 < θ1) for a valid converging closure, and shell enclosure around the network of tubes (hshell > hchannel), so infeasible designs are rejected automatically. Each valid layout is extruded to a 3D geometry in COMSOL automatically, where conjugate heat transfer couples the channel-side and shell-side fluids across the solid wall by solving the incompressible Navier–Stokes and energy equations for laminar and turbulent counter-current operation. All these assignments designed to be automatically for the parametric design. The workflow was demonstrated across variable network dimensions, such as on a representative three-level network (0.5 m² heat-transfer area, 40 mm channel height, diameter and length ratios of 0.75, within a fitted shell). Also, the design was compared against the benchmark by S.A.Marzouk et al from a heat transfer performance point of view. A six-level mesh-independence study spanning 69,781 to 7.46 million elements confirmed numerical convergence, with R² > 0.98 for heat-transfer rate, effectiveness and pressure drop. The simulations reproduced the expected physics: channel velocity fell from trunk (0th level branch) to terminal branches as the total cross-sectional area increased, the channel-side fluid cooled by 11 K while the shell-side fluid warmed by 5 K, and low-velocity thermal "dead zones" formed between branches, directly revealing geometry-driven performance bottlenecks. Because geometry creation, meshing and solving are fully scripted, hundreds of feasible configurations can be evaluated without rebuilding the model manually. LiveLink for MATLAB converts a complex, constraint-heavy fractal design problem into an automated, repeatable COMSOL Multiphysics pipeline. The framework generalises to other branching-network heat exchangers and provides a robust simulation backbone for systematic thermal-hydraulic optimisation.