A statistical mechanics method is proposed for calculation of potential ofmean force (PMF). In the case of solvophobic or solvophilic macroparticles immersed in solvent bathof soft sphere or Lennard-Jones particles, p...A statistical mechanics method is proposed for calculation of potential ofmean force (PMF). In the case of solvophobic or solvophilic macroparticles immersed in solvent bathof soft sphere or Lennard-Jones particles, prediction accuracy for the PMF and MF from the simplestimplementation of the proposed method, where hypernetted chain approximation is adopted forcorrelation of the macroparticle-macroparticle at infinitely dilute limit, is comparable to that ofa recent more sophisticated approach based on mixture Ornstein—Zernike integral equation / bridgefunction from fundamental measure functional. Adaptation of the present method for general complexQuids is discussed, and method for improving the accuracy is suggested. Differences and relativemerits of the present recipe compared with that based on potential distribution theory is discussed.展开更多
The Lagrangian DDM （discrete droplet model） is state-of-the-art for CFD （computational fluid dynamics） simulations of mixture formation and combustion in industrial engines. A commonly known drawback of the DDM ap...The Lagrangian DDM （discrete droplet model） is state-of-the-art for CFD （computational fluid dynamics） simulations of mixture formation and combustion in industrial engines. A commonly known drawback of the DDM approach is the attenuated validity in the dense spray, where the bulk liquid disintegrates into droplets. There the assumption of single droplets surrounded by a homogenous gas field is not reasonable. In this region, the Eulerian-Eulerian multi-phase approach performs better because instead of parcels the spray is represented by the volume fractions of one bulk liquid and several droplet size class phases. A further drawback of the DDM approach is that increasing the spatial resolution of the computational grid leads to a reduced statistical convergence, since the number of spray parcels per computational cell becomes smaller. It is desirable to combine the benefits of both spray approaches in coupled CFD simulations. Therefore, the dense spray region is simulated separately with the Eulerian spray approach on a highly resolved mesh covering only the region close to the nozzle orifice. The entire engine domain with combustion and emission models is simulated with the Eulerian-Lagrangian spray approach for the dilute spray region. The two simulations are coupled through exchange of boundary conditions and model source terms. An on-line coupling interface manages the data transfer between the two simulation clients, i.e., Eulerian spray and engine client. The aim of this work is to extend the coupled spray approach in terms of exchanging combustion related heat and species sources, and consequently creating the link between Eulerian spray and combustion models. The results show mixture formation and combustion in real-case engine simulations, and demonstrate the feasibility of spray model combination in engineering applications.展开更多
The electrohydrodynamic stability of a self-gravitating streaming compound jet has been investigated for all modes of perturbation. The jets are immersed in a dielectric motionless tenuous medium pervaded by varying e...The electrohydrodynamic stability of a self-gravitating streaming compound jet has been investigated for all modes of perturbation. The jets are immersed in a dielectric motionless tenuous medium pervaded by varying electric field. A second-order integrodifferential equation of Mathieu type has been derived and some reported works are recovered as limiting cases from it.展开更多
文摘A statistical mechanics method is proposed for calculation of potential ofmean force (PMF). In the case of solvophobic or solvophilic macroparticles immersed in solvent bathof soft sphere or Lennard-Jones particles, prediction accuracy for the PMF and MF from the simplestimplementation of the proposed method, where hypernetted chain approximation is adopted forcorrelation of the macroparticle-macroparticle at infinitely dilute limit, is comparable to that ofa recent more sophisticated approach based on mixture Ornstein—Zernike integral equation / bridgefunction from fundamental measure functional. Adaptation of the present method for general complexQuids is discussed, and method for improving the accuracy is suggested. Differences and relativemerits of the present recipe compared with that based on potential distribution theory is discussed.
文摘The Lagrangian DDM （discrete droplet model） is state-of-the-art for CFD （computational fluid dynamics） simulations of mixture formation and combustion in industrial engines. A commonly known drawback of the DDM approach is the attenuated validity in the dense spray, where the bulk liquid disintegrates into droplets. There the assumption of single droplets surrounded by a homogenous gas field is not reasonable. In this region, the Eulerian-Eulerian multi-phase approach performs better because instead of parcels the spray is represented by the volume fractions of one bulk liquid and several droplet size class phases. A further drawback of the DDM approach is that increasing the spatial resolution of the computational grid leads to a reduced statistical convergence, since the number of spray parcels per computational cell becomes smaller. It is desirable to combine the benefits of both spray approaches in coupled CFD simulations. Therefore, the dense spray region is simulated separately with the Eulerian spray approach on a highly resolved mesh covering only the region close to the nozzle orifice. The entire engine domain with combustion and emission models is simulated with the Eulerian-Lagrangian spray approach for the dilute spray region. The two simulations are coupled through exchange of boundary conditions and model source terms. An on-line coupling interface manages the data transfer between the two simulation clients, i.e., Eulerian spray and engine client. The aim of this work is to extend the coupled spray approach in terms of exchanging combustion related heat and species sources, and consequently creating the link between Eulerian spray and combustion models. The results show mixture formation and combustion in real-case engine simulations, and demonstrate the feasibility of spray model combination in engineering applications.
文摘The electrohydrodynamic stability of a self-gravitating streaming compound jet has been investigated for all modes of perturbation. The jets are immersed in a dielectric motionless tenuous medium pervaded by varying electric field. A second-order integrodifferential equation of Mathieu type has been derived and some reported works are recovered as limiting cases from it.
