# Dynamics of shadow system of a singular Gierer-Meinhardt system on an evolving domain

## TL;DR

This paper investigates the complex dynamics of a shadow system derived from a singular Gierer-Meinhardt model on an evolving domain, focusing on blow-up phenomena, pattern formation, and stability analysis, supported by numerical simulations.

## Contribution

It introduces a reduced non-local equation for the shadow system on an evolving domain and analyzes its blow-up behavior and pattern stability, extending understanding of reaction-diffusion systems.

## Key findings

- Identification of diffusion-driven blow-up in the non-local equation.
- Observation of Turing instability near stationary solutions.
- Numerical confirmation of theoretical results and comparison with stationary domain cases.

## Abstract

The main purpose of the current paper is to contribute towards the comprehension of the dynamics of the shadow system of a singular Gierer-Meinhardt model on an isotropically evolving domain. In the case where the inhibitor's response to the activator's growth is rather weak, then the shadow system of the Gierer-Meinhardt model is reduced to a single though non-local equation whose dynamics is thoroughly investigated throughout the manuscript. The main focus is on the derivation of blow-up results for this non-local equation, which can be interpreted as instability patterns of the shadow system. In particular, a {\it diffusion-driven instability (DDI)}, or {\it Turing instability}, in the neighbourhood of a constant stationary solution, which then is destabilised via diffusion-driven blow-up, is observed. The latter indicates the formation of some unstable patterns, whilst some stability results of global-in-time solutions towards non-constant steady states guarantee the occurrence of some stable patterns. Most of the derived results are confirmed numerically and also compared with the ones in the case of a stationary domain.