Molecular dynamics simulation of the transport and structural properties for methanol-octane blends at engine-relevant conditions

R Kashyap and K Saha and KA Subramanian, INTERNATIONAL JOURNAL OF GREEN ENERGY (2025).

DOI: 10.1080/15435075.2025.2475154

In this work, the transport and structural properties of methanol-octane blends are predicted over a range of pressures from 1 bar to 200 bar and temperatures from 303 K to 363 K by using molecular dynamics (MD) simulation. The simulation results were compared and validated against NIST data and experimental data from the literature, demonstrating good agreement in terms of density and viscosity. The results for both M15 (methanol mole fraction: 15% and octane mole fraction: 85%) and M85 (methanol mole fraction: 85% and octane mole fraction:15%) blends showed that density and viscosity increase with the rise in pressure and decrease with the rise in temperature, while diffusivity decreases with pressure and increases with temperature. The radial distribution function (RDF) was calculated to examine the structural changes resulting from variations in pressure and temperature. The analysis revealed that the peak magnitude of RDF decreases with increasing temperature, indicating reduced molecular aggregation. Bond length calculations demonstrated that bond length increases with temperature and decreases with pressure. Energy analysis showed that both potential energy and total energy rose with increasing temperature due to a gain in thermal energy and decreased with increasing pressure due to reduced particle mobility.

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