The effects of nanoparticle percentages and an external variable magnetic field on the atomic and thermal behaviors in an oscillating heat pipe via molecular dynamics simulation

Abstract

• An OHP is a two-phase heat transfer device with a high effective thermal conductivity. • Using the MD simulation method, this work investigates the atomic and thermal behaviors of nanofluid in an OHP. • A variable external magnetic field is applied to the simulated studied structure. • As the amplitude increases (1 T to 5 T), the HF increases to the maximum value. • The presence of an external field improves the thermal performance in an OHP. In today’s world, heat transfer is a phenomenon that occurs in many important industrial processes. Due to its heat transfer properties and ability to enhance thermal conductivity, nanofluid is a contender for an oscillating heat pipe (OHP). This paper studies the atomic and thermal properties of Fe 3 O 4 /water nanofluid in an OHP with copper (Cu) walls using molecular dynamics (MD) simulations. Thus, the effects of different percentages of Fe 3 O 4 nanoparticles on the density, velocity, temperature profiles, and heat flux (HF) are investigated after 20 ns. The results show as the nanoparticles percentages increase from 1% to 4%, HF value increases from 1561 W/m 2 to 1602 W/m 2, and maximum velocity decreases from 0.044 to 0.038 (Å /ps). The effects of a magnetic field on the density, temperature, velocity and heat transfer profiles were investigated. As the magnetic field amplitude increases (1 T to 5 T), HF increases to the maximum value (1603 W/m 2 ). Besides, as the applied magnetic field increases from 1 T to 5 T, the maximum velocity and temperature increase from 0.048 (Å /ps) and 451 K to 0.068 (Å /ps) and 492 K, respectively, but the maximum density decreases from 0.021 to 0.017 (atom/ Å 3 ). The presence of an external field enhances the thermal performance of the nanofluid in an OHP, hence increasing its use in electronic systems. This study enhances OHPs' thermal behaviour and heat transmission in nanofluids, making them more suitable for medical and industrial applications.