Unveiling the thermal-induced molecular dynamics in fluids: A graph-based heat flow analysis

Abstract

This paper is the first report of delineating the potential of the graph features in unveiling the complex molecular dynamics in fluids by analyzing the thermal lens signal during the transient heat flow. For this, the thermal lens signals of the three fluids (acetone, ethylene glycol, and coconut oil) of different viscosities are subjected to the complex network analysis after curve fitting the signal. The dynamics is further investigated by segmenting the signal into two. When the rapid change of enthalpy appears as clusters in the graph, the quasi-steady state appears as uncorrelated nodes. The increased enthalpy in the second region accounts for the low refractive index, random molecular dynamics, and uncorrelated nodes. The transition time demarcating the two regions is found to increase with the viscosity of the fluid. The role of viscosity on the features of the graph is also clearly brought out. This study unveils the potential of graph-based features in the heat flow analysis and their suitability for applications in thermal engineering.