Browsing by Author "Keivani, Babak"

Now showing 1 - 3 of 3

Citation Count: 1
The computational study of silicon doping and atomic defect influences on the CNT's nano-pumping process: Molecular dynamics approach
(Pergamon-elsevier Science Ltd, 2024) Hao, Yazhuo; Salahshour, Soheıl; Bagheritabar, Mohsen; Jasim, Dheyaa J.; Keivani, Babak; Kareem, Anaheed Hussein; Esmaeili, Shadi
Today, nanotubes are used in biological systems due to their low toxicity and unique functionalization capability. Carbon nanotubes (CNTs) are considered one of the best carriers in drug delivery systems. In this study, the effect of silicon (Si) doping and atomic defects on the CNT's nano-pumping process has been investigated by molecular dynamics (MD) simulation, and the changes in kinetic energy, potential energy, entropy, stress, and nanopumping time are investigated. The results show that increasing Si doping increases CNT's C20 molecule exit time. Numerically, as the Si doping increases from 0.05% to 4%, the exit time of the C20 molecule increases from 8.07 to 9.16 ps. Also, an increase in Si doping leads to a decrease in kinetic energy and lattice stress and an increase in the potential energy and entropy of the system. So, the nanostructure with 1% doping performs better (optimal performance) than other samples. The effect of atomic defect with 0.5%, 1% and 1.5% on CNT's surface is investigated. The results show that the kinetic energy of samples decreases by increasing atomic defect from 0.5% to 1.5%. Also, the results show that the kinetic energy of the sample with a 0.5% atomic defect is higher than its defect-free state. The numerical results show that potential energy and entropy increase with the increasing the atomic defect. This increase can lead to an increase in the time it takes for the nanoparticle to exit the nanotube and disrupt the nano-pumping process.
Citation Count: 0
Investigating the effect of the number of layers of the atomic channel wall on Brownian displacement, thermophoresis, and thermal behavior of graphene/water nanofluid by molecular dynamics simulation
(Elsevier, 2024) Guo, Xinwei; Salahshour, Soheıl; Alizadeh, Asad; Keivani, Babak; Nasajpour-Esfahani, Navid; Salahshour, Soheil; Sabetvand, Rozbeh
Nanofluids (NFs) are nanoscale colloidal suspensions containing dense nanomaterials. They are two-phase systems with solid in liquid phase. Due to their high thermal conductivity, nano -particles increase the thermal conductivity (TC) of base fluids, one of the basic heat transfer parameters, when distributed in the base fluids. The present research investigates the thermal behavior, Brownian motion, and thermophoresis of water/graphene NF affected by different numbers of atomic wall layers (4, 5, 6 and 7) by molecular dynamics (MD) simulation. This investigation reports changes in heat flux (HF), TC, average Brownian displacement, and ther-mophoresis displacement. By raising the number of atomic wall layers from 4 to 7, the average Brownian displacement and thermophoresis displacement increase from 3.06 angstrom and 23.88 angstrom to 3.62 and 25.05 angstrom, respectively. Increasing the number of layers due to the decrease in temper-ature increases the temperature difference between the hot and cold points along the channel. It increases the Brownian motion and the maximum temperature. Additionally, by raising the atomic layers of the channel wall, the values of HF and TC increase from 39.54 W/m2 and 0.36 W/mK to 41.18 W/m2 and 0.42 W/mK after 10 ns, respectively. The temperature rose from 1415 to 1538 K. These results are useful in different industries, especially for improving the thermal properties of different NFs.
Citation Count: 1
Thermal performance of forced convection of water- NEPCM nanofluid over a semi-cylinder heat source
(Elsevier, 2024) Wang, Xiaoming; Salahshour, Soheıl; Keivani, Babak; Jasim, Dheyaa J.; Sultan, Abbas J.; Hamedi, Sajad; Toghraie, Davood
1) Background: Phase change materials (PCMs) have been used statically, which has caused the use of these materials to face challenges. Encapsulating PCMs and combining them with the base fluid can significantly solve the problem of using PCMs in BTM systems. In the present study, based on computational fluid dynamics, forced convection heat transfer of nano -encapsulated phase change materials (NEPCM) in a BTM system are simulated. The main aim of the present research is to reduce the temperature at the surface of the hot cylinder. 2) Methods: In this research, we simulated lithium battery thermal management systems in both steady and transient states. The effects of using NEPCM particles to water were investigated. Modeling is implemented using the finite volume method and the PIMPLE and SIMPLE algorithms in OpenFoam. Furthermore, the effects of battery heat flux, Reynolds number, and the presence of nanoparticles (NPs) were analyzed. We intend to evaluate the optimal state of the system by studying the mentioned parameters. 3) Significant Findings: Our study shows that adding 3.5% NEPCM to water can reduce the length of the vortex by 22% and in unsteady -state simulation, it is observed that the presence of NEPCM particles in water reduces battery temperature up to 0.66 K.