Evolution of vortex structures in round jet was simulated with a three-dimensional discrete vortex filament method. The motion of the particles was described by a Lagrangian equation and the counteraction of particles...Evolution of vortex structures in round jet was simulated with a three-dimensional discrete vortex filament method. The motion of the particles was described by a Lagrangian equation and the counteraction of particles on the flow was taken into account by using a modified velocity model. It is indicated that in two-phase jet flow the introduced particles restrain the crosswise dispersion of jet shear layer and mergence of vortex structures. With the increase of St number, the influence of flow on particles motion is decreased, but the counteraction of particles on the flow is increased. The difference of flow field obtained with two models, one-way coupling model and two-way coupling model, is greater than that of particles trajectories.展开更多
Kelvin-Helmhotz roll up of the 3-D time-developing mixing was simulated numerically. The dye lines or fluid interfaces were presented by computing a passive scalar at high Peclet number. The hydric bubbles were also s...Kelvin-Helmhotz roll up of the 3-D time-developing mixing was simulated numerically. The dye lines or fluid interfaces were presented by computing a passive scalar at high Peclet number. The hydric bubbles were also simulated numerically. To help understanding the visualization results, the behaviour of coherent structures were analyzed. A comparison between vortical structure and passive scalar contours indicates that the wrapping by the vortices largely dominates the evolution of passive scalar.展开更多
The motion of cylindrical particles in a wedge-shaped flow was studied. The velocity distribution of wedge-shaped flow was simulated and then the Euler-Lagrange model was used to calculate the motion of cylindrical pa...The motion of cylindrical particles in a wedge-shaped flow was studied. The velocity distribution of wedge-shaped flow was simulated and then the Euler-Lagrange model was used to calculate the motion of cylindrical particles. The evolution of particle location, velocity and orientation with time was examined. The trajectories of the particles with different particle Stokes number, rate of flow and initial particle orientation were drawn. The results indicate that the Stokes number and initial orientation are important parameters which mainly affect the particle motion.展开更多
The stability of flow with suspended solid particles has been examined by analyzing the expanded Ors-Sommerfeld equation.A series of numerical simulations varying particle size, particle loading, particle density and ...The stability of flow with suspended solid particles has been examined by analyzing the expanded Ors-Sommerfeld equation.A series of numerical simulations varying particle size, particle loading, particle density and ratio of particle velocity to fluid velocity have been conducted. The results show that smaller particles and lighter particles will make instability easier. Increasing ratio of particle velocity to fluid velocity is found to be a destabilizing mechanism. The instability is enhanced as the particle loading increases.展开更多
文摘Evolution of vortex structures in round jet was simulated with a three-dimensional discrete vortex filament method. The motion of the particles was described by a Lagrangian equation and the counteraction of particles on the flow was taken into account by using a modified velocity model. It is indicated that in two-phase jet flow the introduced particles restrain the crosswise dispersion of jet shear layer and mergence of vortex structures. With the increase of St number, the influence of flow on particles motion is decreased, but the counteraction of particles on the flow is increased. The difference of flow field obtained with two models, one-way coupling model and two-way coupling model, is greater than that of particles trajectories.
基金This work is supported by the National Natural Science Foundation of China as well as ZhejlangProvince Natural Science Special Fund for Youth Seientists Cultivation.
文摘Kelvin-Helmhotz roll up of the 3-D time-developing mixing was simulated numerically. The dye lines or fluid interfaces were presented by computing a passive scalar at high Peclet number. The hydric bubbles were also simulated numerically. To help understanding the visualization results, the behaviour of coherent structures were analyzed. A comparison between vortical structure and passive scalar contours indicates that the wrapping by the vortices largely dominates the evolution of passive scalar.
基金This work was supported by the Trans- Century Training Programme Foundation for theTalents by the State Education Commission o
文摘The motion of cylindrical particles in a wedge-shaped flow was studied. The velocity distribution of wedge-shaped flow was simulated and then the Euler-Lagrange model was used to calculate the motion of cylindrical particles. The evolution of particle location, velocity and orientation with time was examined. The trajectories of the particles with different particle Stokes number, rate of flow and initial particle orientation were drawn. The results indicate that the Stokes number and initial orientation are important parameters which mainly affect the particle motion.
文摘The stability of flow with suspended solid particles has been examined by analyzing the expanded Ors-Sommerfeld equation.A series of numerical simulations varying particle size, particle loading, particle density and ratio of particle velocity to fluid velocity have been conducted. The results show that smaller particles and lighter particles will make instability easier. Increasing ratio of particle velocity to fluid velocity is found to be a destabilizing mechanism. The instability is enhanced as the particle loading increases.
