A lattice Boltzmann method for simulating the viscous flow in large distensible blood vessels is presented by introducing a boundary condition for elastic and moving boundaries. The mass conservation for the boundary condition is tested in detail. The viscous flow in elastic vessels is simulated with a pressure-radius relationship similar to that of the pulmonary blood vessels. The numerical results for steady flow agree with the analytical prediction to very high accuracy, and the simulation results for pulsatile flow are comparable with those of the aortic flows observed experimentally. The model is expected to find many applications for studying blood flows in large distensible arteries, especially in those suffering from atherosclerosis, stenosis, aneurysm, etc.

This paper studies phase diagrams of traffic flow at an unsignalized intersection consisting of two perpendicular one-lane roads, employing parallel update rules and yield dynamics. Based on theoretical analysis and computer simulations, we have presented the phase diagram for the cases of various maximum vehicle velocities, and it is found that the phase diagram has several different topology structures. The flow formulas in all regions in the phase diagram have been derived. The results of theoretical analysis are in good agreement with the simulation ones.

No abstract

Traffic flow at a single crossroad consisting of two perpendicular one-lane roads, treated earlier by Ishibashi and Fukui [J. Phys. Soc. Jpn.70, 2793 (2001); 70, 3747 (2001)], has been studied on the basis of the local occupation probability method. However, in this work, based on the novel theoretical analysis and computer simulations, we have studied this crossroad traffic model again and presented the same phase diagrams of traffic flow in the case of various maximum vehicle velocities. We have also derived the flow formulas in all regions in the phase diagrams, which are in good agreement with computer simulation results. Compared with the previous local occupation probability method, our analytical way is simpler and may be widely used for other traffic bottlenecks research.

In this context, we introduce anticipation headway to modify the Noise-First NaSch model under condition of periodic boundary. The traffic situation with different parameters can be numerical simulated. It was indicated that the Noise-First model with added anticipation headway is more realistic in reflecting traffic flow. Not only start-stop wave and synchronized flow but also the metastable state can be obtained by numerical simulation. The modified model can reproduce nonlinear phenomena which tallies with the real traffic.