Takahiro Ikeda | Searcharxiv

arXiv2026

Dimensional Crossover of Thermal Transport in Nanoconfined Liquids Driven by the Interplay of Quasi-One-Dimensional Structure and Wall Dissipation

Heat transport in nanoconfined liquids can deviate from ordinary Fourier behavior because confinement alters liquid structure and interfacial dissipation. Although such changes may lead to quasi-one-dimensional transport or overdamped sound relaxation, the conditions under which length-dependent transport persists remain unclear. Here we use molecular dynamics simulations of monatomic liquid argon confined in carbon nanotubes with systematically varied radii and lengths. We find a radius-controlled crossover: length-dependent axial thermal conductivity persists over long tube lengths in single-file and single-shell states, but is strongly truncated or nearly saturated once mixed-shell or multilayer packing develops. This crossover is accompanied by the loss of clear acoustic-like axial modes and enhanced wall--liquid friction. Thus, tube radius controls whether length-dependent heat transport persists or is truncated by coupling confined-liquid structure to wall-induced dissipation.

cond-mat.soft↗

arXiv2024

Structure and dynamics of amphiphilic patchy cubes in a nanoslit under shear

Patchy nanocubes are intriguing materials with simple shapes and space-filling and multidirectional bonding properties. Previous studies have revealed various mesoscopic structures such as colloidal crystals in the solid regime and rod-like or fractal-like aggregates in the liquid regime of the phase diagram. Recent studies have also shown that mesoscopic structural properties, such as average cluster size $\left\langle M \right\rangle$ and orientational order, in amphiphilic nanocube suspensions are associated with macroscopic viscosity changes, mainly owing to differences in cluster shape among patch arrangements. Although many studies have been conducted on the self-assembled structures of nanocubes in bulk, little is known about their self-assembly in nanoscale spaces or structural changes under shear. In this study, we investigated mixtures of one- and two-patch amphiphilic nanocubes confined in two flat parallel plates at rest and under shear using molecular dynamics simulations coupled with multiparticle collision dynamics. We considered two different patch arrangements for the two-patch particles and two different slit widths $H$ to determine the degree of confinement in constant-volume fractions in the liquid regime of the phase diagram. We revealed two unique cluster morphologies that have not been previously observed under bulk conditions. At rest, the size of the rod-like aggregates increased with decreasing $H$, whereas that of the fractal-like aggregates remained constant. Under weak shear with strong confinement, the rod-like aggregates maintained a larger $\left\langle M \right\rangle$ than the fractal-like aggregates, which were more rigid and maintained a larger $\left\langle M \right\rangle$ than the rod-like aggregates under bulk conditions.

cond-mat.soft↗