Effect of Morphology-dependent interfacial structuring on the Thermophysical properties of aqueous Cu-nanofluids: insight from molecular dynamics study

<title>Abstract</title> <p>This study presents an equilibrium molecular dynamics (EMD) investigation of the influence of nanoparticle shape on the thermophysical properties of copper (Cu) nanofluids at 303 K. Nanoparticles with spherical, cubic, and cylindrical geometries are dispersed in a base fluid to examine the effect of particle morphology on thermal transport. Thermal conductivity and viscosity are evaluated using the Green–Kubo formalism based on the heat current and stress autocorrelation functions, respectively, while the specific heat capacity is determined from equilibrium energy fluctuations. Structural and dynamical characteristics are analyzed through radial distribution functions (RDF) and mean square displacement (MSD). The RDF results reveal morphology-dependent interfacial structuring, whereas the MSD analysis indicates enhanced self-diffusion with increasing particle–fluid interfacial area. Cylindrical and cubic nanoparticles exhibit higher thermal conductivity and specific heat capacity than spherical nanoparticles, accompanied by an increase in viscosity resulting from stronger particle–fluid interactions. Furthermore, the interfacial thermal resistance (Kapitza resistance) is quantified to elucidate the influence of nanoparticle geometry on heat transfer across the solid–fluid interface. A reduction in Kapitza resistance is observed for anisotropic nanoparticles, contributing to enhanced thermal conductivity. Overall, these findings provide atomistic insights into the shape-dependent transport behavior of Cu nanofluids and offer valuable guidance for the rational design of high-performance nanofluid systems.</p>