ISSN: 2574-187X
Authors: Osuga T*
The reason why the measured self-diffusional coefficient, selfDmeas, of the liquid Brownian particle (LBP) tends to be greater than the analytically expected coefficient, selfDanal, was found to be the thermal transfer without the use of the slipping condition (slipping through the liquid molecular gap leads to an extended random walk time step Ï„w, which is observed as the enhanced selfDmeas). Assuming that the diffusive thermal transfer (DTF) causes a converging heat inflow towards the LBP center uniformly from the surroundings with the thermal diffusivity ratio χ (= λ/Cp Ï) and the advective thermal transfer (ATF) carries heat to the LBP front using the arriving flow with the thermal velocity of the LBP, the diffusive-to-advective thermal transfer ratio (DAR), which represents the balance between the DTF and ATF, was calculated to predict the ratio selfDmeas/selfDanal, which represents the selfDmeas enhancement in water, alcohol, and alkane at 25 °C. The partial mass freedom Nprt associated with the atomic group rotations of the LBP is more than eight times the total mass freedom associated with the directional change of the random walk. Furthermore, the viscous dissipation period of Nprt is significantly shorter than Ï„w. Therefore, the LBP preferred the energy supply to Nprt rather than the directional change according to the equipartition theorem, leading to the Ï„w extension. The tendency of selfDmeas to significantly exceed selfDanal in most liquid molecules was found to be due to the Ï„w extension because selfDmeas∠τw.
Keywords: Stokes Einstein equation; Stokes Einstein Sutherland equation; Dielectric relaxation; Equipartition law of energy; Stokes’ law; Spherical thermal conduction; Van der Waals constant
