_applied sciences_  
_Article_  
Study of Temperature Effect on Cascade Characteristics of  
Nanofluidic Energy Absorption System  
[PERSON] 1,2,*\(\copyright\), [PERSON] 1,2, [PERSON] 1,2, [PERSON] 1,2, [PERSON] 1,2\(\copyright\) and [PERSON] 1,2,*  
Footnote 64: foot compression test with NEAS composed of ZSM-5 zeolite/\(\beta\) zeolite and deionized water [34]. In addition, there is a limited amount of literature available on the investigation of cascade nanofluidic systems. The cascade NEAS has multiple platforms on the pressure-volume curve, corresponding to multiple pressure thresholds. Thus, it can absorb energy on different levels simultaneously in one system and greatly expand the scope of NEAS. For example, it can be engineered as a lightweight material for the vehicle body or a collision avoidance system in modern automobiles, which can absorb vibrations to enhance ride comfort while also absorbing impact to ensure safety. However, NEAS composed of nanoporous media with different pore size does not necessarily exhibit cascade energy storage characteristics due to the existence of viscous dissipation between liquid-solid phases. It is crucial to determine the critical pore size difference of establishing the NEAS cascade energy storage characteristic, which is indispensable in designing and implementing such a system.  
Of all the external effected influences, temperature plays a key role in determining the motion of molecules. The liquid viscosity [35; 36] and hydrophobicity [37; 38] at the nanoscale are both influenced by temperature, which was utilized for nanofluids forced convection heat transfer [39; 40; 41] in recent research. The alteration of system temperature will undoubtedly impact the formation of cascade NEAS, and it is widely believed that temperature is one of the most influential factors in manipulating fluid dynamics. Over the past decade, there were great achievements in transporting water through narrow CNTs in experiments and computer simulations [38; 42; 43]. However, the temperature-dependent transport behavior of liquid infiltrate through nano channels with multiple pore sizes remains unexplored.  
Because the pore size distribution of most porous materials use in application is non-uniform [44], it is challenging to experimentally investigate the cascade energy storage properties of nanoporous media. Molecular dynamics simulation provided a novel approach for investigating this field. LAMMPS is a classical molecular dynamics code with a focus on materials modeling. It was used by many scholars to conduct molecular dynamics simulations of liquid transport in nano channels [45]. [PERSON] et al. explored the working mechanism of nano porous energy absorption systems under high-speed impact loading conditions through molecular dynamic simulation., and illuminated the effects of pipe diameter and loading rate [46; 47]. [PERSON] et al. established an improved carbon nanocone model using LAMMPS software, and verified the correctness of using LAMMPS software for numerical simulation [48]. [PERSON] et al. reported molecular dynamics simulations showing spontaneous and continuous filling of a nonpolar carbon nanotube with a one-dimensionally ordered chain of water molecules [49]. [PERSON] et al. conducted research on the temperature-dependent intrusion/adsorption of water molecules into hydrophobic carbon nanotubes and nanoporous carbon [50]. [PERSON] et al. investigated the flow of aqueous solution of sodium chloride driven by the temperature gradient and the performance of voltage generation in CNT [51].  
In the present work, molecular dynamics simulations were conducted on two distinct pore configurations to investigate the impact of temperature-coupled pore size of porous media on characteristics of cascade NEAS. The fitting correlation between critical pore size difference and temperature was obtained, and the microscopic mechanism of temperature effect was illuminated. The research findings expanded the fundamental database of cascade NEAS and offer guidance for its application design.