Browsing by Author "Emami, Nafiseh"

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Citation Count: 0
The effect of initial pressure and atomic concentration of iron nanoparticles on thermal behavior of sodium sulfate/magnesium chloride hexahydrate nanostructure by molecular dynamics simulation
(Elsevier, 2024) Huang, Yijin; Salahshour, Soheıl; Kaur, Mandeep; Basem, Ali; Khaddour, Mohammad H.; Al-Bahrani, Mohammed; Emami, Nafiseh
Thermal energy storage (TES) is one of the uses of phase change material (PCM). The primary factor contributing to this capability is the elevated latent heat of melting present in these materials. The current study investigates the effect of initial pressure (IP) (ranging from 1 to 5 bar), and atomic ratio (AR) of Iron nanoparticles (NPs) (Fe = 1, 2, 3, and 5 %) on the thermal behavior (TB) and phase transition process of sodium sulfate/Magnesium chloride hexahydrate (Na 2 SO 4 /MgCl 2 & sdot; 6H 2 O) nanostructures as PCMs using molecular dynamics (MD) simulation. The simulated PCM was positioned inside a spherical atomic channel composed of iron. The TB of simulated nanostructures was examined by reporting changes in viscosity (Vis), thermal conductivity (TC), and phase transition time (PTT). The results reveal that by increasing IP from 1 to 5 bar, the PTT reaches from 3.50 to 3.61 ns, and the TC decreases from 1.03 to 0.94 W/m.K. The results show that adding 3 % of Fe NPs was the optimal ratio to improve the TB of the Na 2 SO 4 /MgCl 2 & sdot; 6H 2 O-Fe NP. By raising the ratio of Fe NPs from 1 to 3 %, Vis slightly decreased from 4.31 to 4.22 mPa.s. In comparison, adding more Fe NPs with 5 % ratio raised the Vis to 4.30 mPa.s. According to the results, increasing the IP decreased the distance among the particles. So, the attraction among particles increased, leading to greater adhesion and Vis. By increasing the IP, the distance among atoms decreases, and the space between NPs and atoms in the simulation box decreases. Consequently, NP movement and fluctuations decrease, and collisions decrease. The results of this simulation will be effective in heating - cooling and ventilation systems, automotive industries, textile industries, and so on.
Citation Count: 0
Effects of variable electric field on crack growth of aluminum nanoplate: A molecular dynamics approach
(Pergamon-elsevier Science Ltd, 2024) Salahshour, Soheıl; Hammoodi, Karrar A.; Fadhil, Dalal Abbas; Hanoon, Zahraa A.; Nayyef, Dhuha Radhi; Salahshour, Soheil; Emami, Nafiseh
Studying cracks in aluminum (Al) nanosheets is crucial because it enhances our understanding of their mechanical properties and failure mechanisms, which are vital for applications in lightweight structures, electronics, and nanotechnology. In this study, different levels of an external electric field (EF) (1, 2, 3, and 5 V/& Aring;) were used to see how they affected the growth of nanocracks in Al nanoplates. This investigation was carried out utilizing molecular dynamics simulation and LAMMPS software. Increasing EFA to 2 V/& Aring; increased to maximum (Max) stress from 230.567 to 242.032 GPa. Furthermore, increasing the voltage to 5 V/& Aring; reduced Max stress to 230.567 GPa. Max (Vel) occurred in the presence of 2 V/& Aring; which reached 14.2192 & Aring;/ps. The increase in atomic Vel in Al nanoplates can be attributed to enhanced atomic collisions and energy transfer among atoms as the EFA increases to 5 V/& Aring;, the Vel declined to 11.9908 & Aring;/ps. On the other hand, the outputs predicted the atomic evolution of designed Al nanoplates can manipulate the EF value changes. Numerically, by changing the EF parameter from 1 to 5 V/& Aring;, the nano-crack length value varied from 27.87 to 30.16 & Aring;. Physically, this structural evolution occurred through changes in interaction energy (mean attraction energy) within various regions of Al nanoplates. In industrial cases, this nano-crack length manipulation by EF amplitude parameter can be used to prepare atomic nanoplates with different resistances to the crack growth process.
Citation Count: 0
Examination of the mechanical properties of porous carbon matrix by considering the Nanovoids: A computational study using molecular dynamics simulation
(Pergamon-elsevier Science Ltd, 2025) Sun, Shuai; Ali, Ali B. M.; Babadoust, Shahram; Al-Zahiwat, Murtadha M.; Kumar, Raman; Chaudhary, Rahul Raj; Emami, Nafiseh
This study explored the effect of nanovoid size on the mechanical properties of polymer-carbon matrices through detailed molecular dynamics simulations. The investigation focused on spherical nanovoids with radii of 5, 7, 10, 12, and 15 & Aring;, evaluating their effects on critical mechanical properties, such as Young's modulus and ultimate strength. The Tersoff potential was employed to accurately model the atomic and mechanical behavior of the polymer-carbon matrix, considering the presence of these nanovoids. The simulation results indicate that the potential energy and total energy stabilized at-132,279.23 eV and- 131,522.4 eV, respectively, confirming the physical stability of simulated samples. On the other hand, the findings reveal that for a nanovoid radius of 5 & Aring;, the ultimate strength and Young's modulus were 36.41 GPa and 424.93 GPa, respectively. As the radius of nanovoids increased from 5 & Aring; to 15 & Aring;, both ultimate strength and Young's modulus exhibited a decreasing trend, with values dropping from 36.41 GPa and 424.93 GPa to 31.18 GPa and 364.39 GPa, respectively. Moreover, larger nanovoids contributed to increased flexibility and a higher critical strain in the polymer-carbon matrix. This systematic analysis of nanovoid size effects provided a new perspective on void engineering within composites. By enhancing the theoretical understanding of how void dimensions affected material properties, the study offered significant insights for optimizing the mechanical performance of advanced materials and advancing the field of structural engineering.
Citation Count: 0
Numerical study of changes in the mechanical and thermal property of porous silicon sample with increasing initial temperature: A molecular dynamics approach
(Pergamon-elsevier Science Ltd, 2024) Liu, Shupeng; Ali, Ali B. M.; Hussein, Muntadher Abed; Kumar, Anjan; Abduvalieva, Dilsora; Abdul-Redha, Hadeel Kareem; Emami, Nafiseh
The mechanical and thermal properties of porous silicon samples were examined in this investigation in relation to their initial temperature (Temp). The molecular dynamics (MD) numerical simulation method was employed to analyze the results, and LAMMPS software was used to model the porous sample. The simulations conducted in the present study predicted the physical equilibrium of porous silicon samples that were modeled. The research results indicate that the ultimate strength and Young's modulus of porous structures decreased from 26.559 and 52.484 GPa to 25.830 and 52.304 GPa as the Temp increased from 300 to 500 K. The results indicate that the toughness decreased from 10.788 eV/& Aring;3 to 10.195 eV/& Aring;3 as the initial Temp increased to 500 K. Additionally, MSD and diffusion coefficient of porous silicon sample increased from 3.88 nm2 and 27.86 nm2/ns to 8.67 nm2 and 75.56 nm2/ns when the Temp increased from 300 K to 500 K. As the Temp increases to 500 K, the COM increases from 0.236 to 0.41 & Aring;. The total energy of system decreases to -29,259.648 eV when the initial Temp of the porous silicon sample increases to 500 K. Changes in the atomic-scale dynamics and the structural properties of porous silicon network were responsible for this tendency. This study's novelty lies in its focus on the unknown relationship between Temp and porous silicon performance. The results of this study indicate that the Temp had a significant effect on the mechanical and thermal properties of porous silicon samples. These findings are necessary to advance the practical use of porous silicon in various technological fields, especially in Tempsensitive applications, where understanding its behavior under different thermal conditions is very important.