Growth and form of a self-constructing tube network

Area of Science:

• Fluid dynamics
• Materials science
• Chemical reactions

Background:

• Fluid jets typically have limited propagation distance.
• Chemical reactions at interfaces can create flexible membranes.
• Such membranes can enable the formation of complex fluid structures.

Purpose of the Study:

• To describe the tube networks formed by injecting aluminum chloride (AlCl3) into sodium hydroxide (NaOH).
• To analyze the morphology, growth, and branching characteristics of these structures.
• To develop a model explaining the observed phenomena.

Main Methods:

• Quick injection of AlCl3 solution into NaOH solution.
• Observation and characterization of the resulting tubular structures.
• Development of a theoretical model for structure formation.

Main Results:

• Formation of straight tubular stems with 2-5 symmetric branches.
• Structures exhibit high aspect ratios (propagation distance to stem width up to 50).
• Growth occurs via membrane stretching; spontaneous branching and junction splitting observed.
• Model explains branching symmetry and flow rate insensitivity.

Conclusions:

• Chemical reaction-induced membrane formation facilitates the creation of extensive, branching tube networks.
• The observed structures and their growth dynamics are governed by membrane mechanics and reaction kinetics.
• A model successfully predicts key features of the branching and growth, including symmetry and flow rate independence.