英语翻译If the initial position of a particle falls on the cente

英语翻译
If the initial position of a particle falls on the centerline of
the channel,the particle always stays on the centerline and
the velocity at stenosis throat is much larger than that in the
flat tube as shown in Fig.4.The case is more complex when
the particle is positioned away from the centerline initially.
The snapshots of the positions and orientations of the particle
are displayed in Fig.5 for the initial position of the particle
2d above the centerline.Near the protuberance the particle
moves to the centerline of the tube.However,the particle
never arrives at the centerline.After passing the stenosis,the
particle migrates to the same direction of the initial position,
i.e.,the particle migrates up since the initial position of the
particle is above the centerline.This is consistent with the
Segre´-Silberberg effect @7# observed in flat pipe flow that
neutrally buoyant cylinders migrate laterally away from both
the wall and the centerline and reach a certain lateral equilibrium
position.Figure 6 shows the velocity and angular
velocity of the particle with respect to t and x.The x component
of the velocity at stenosis throat is about five times of
that in the flat tube.The y component of the velocity changes
its direction from upstream to downstream of the stenosis.
The angular velocity at the throat is not so smooth as that of
the x or y component of the velocity.This results from that
the particle sometimes touches the upper protuberance near
the stenosis throat like a skier.When the particle touches the
upper protuberance,there is friction on the surface between
the upper protuberance and the particle.Although the friction
is very small,it gives a relatively large torque since it acts on
the surface of the particle and is perpendicular to the connection
line between the contact point and the center of the
particle.Figure 7 shows the streamline in the tube.

500财富,如果粒子的初始位置落在中心线通道,粒子始终保持中心线在狭窄喉咙的速度是远大于在扁管,如图.4.案件更加复杂粒子的位置从最初的中心线.粒子的位置和方向的快照显示图.5个粒子的初始位置2D中心线以上.近突起...