In this article, the eff ect of surface roughness size and shape on the Poiseuille fl ow of Ar–Cu nanofl uid in a square copper

nanochannel is investigated. To do this, hemispherical, cubic, semi-cylindrical roughness, shapes extended along the nanochannel

length and width, and square protrusions extended along the nanochannel length and width are studied. The simulations

are carried out using the molecular dynamics method and LAMMPS software. The results show that the roughness

causes a change in the velocity and structure of nanofl uid atoms in the nanochannel. For example, the hemispherical roughness

with a height of 7.5Å causes 24% decrease in the nanofl uid velocity. Also, the results show that the eff ect of diff erent

shapes and sizes of roughness on the nanofl uid behavior is diff erent. For example, at the same height of roughness ( 7.5Å ),

the velocity diff erence created by diff erent roughness shapes is around 0.208

Å

ps

, which is around 13% of the nanofl uid velocity

in the smooth state. Additionally, it is found that the roughness makes the nanofl uid velocity profi le fl atter in the central part

of the nanochannel. Also, the results reveal that the shape and height of the roughness have an eff ect on the aggregation time

of nanoparticles and on how they move in the nanofl uid. Specifi cally, increasing the height of the roughness and decreasing

the velocity of the nanofl uid, decreases the accumulation time of nanoparticles.

Molecular dynamics simulation · Nanofl uid behavior · Nanoparticles aggregation · Surface roughness · Square nanochannel

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