Biological Growth in Bodies with Incoherent Interfaces

TL;DR

This paper develops a comprehensive thermodynamic model for biological growth considering incoherent interfaces, nutrient transport, and stress, with applications to tree ring formation and wound healing.

Contribution

It introduces a novel theory accounting for incoherent interfaces in biomechanical growth, integrating nutrient dynamics and stress analysis.

Findings

Model successfully describes growth phenomena in trees and animals.

Incoherent interfaces significantly influence internal stress and growth patterns.

Theoretical predictions align with observed biological growth processes.

Abstract

A general theory of thermodynamically consistent biomechanical--biochemical growth in a body, considering mass addition in the bulk and at an incoherent interface, is developed. The incoherency arises due to incompatibility of growth and elastic distortion tensors at the interface. The incoherent interface therefore acts as an additional source of internal stress besides allowing for rich growth kinematics. All the biochemicals in the model are essentially represented by nutrient concentration fields, in the bulk and at the interface. A nutrient balance law is postulated which, combined with mechanical balances and kinetic laws, yields an initial-boundary-value problem coupling the evolution of bulk and interfacial growth, on one hand, and the evolution of growth and nutrient concentration on the other. The problem is solved, and discussed in detail, for two distinct examples: annual ring formation during tree growth and healing of cutaneous wounds in animals.