In fluid dynamics, the Stokes stream function is used to describe the streamlines and flow velocity in a three-dimensional incompressible flow with axisymmetry. A surface with a constant value of the Stokes stream function encloses a streamtube, …

When used as a celestial coordinate, the azimuth is the horizontal direction of a star or other astronomical object in the sky. The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5 km radius at sea level) around an observer on Earth's surface, and the reference vector points to true north.

Free-floating test particles reveal the velocity and vorticity pattern. The Rankine vortex is a simple mathematical model of a vortex in a viscous fluid. It is named after its discoverer, William John Macquorn Rankine. The vortices observed in nature are usually modelled with an irrotational (potential or free) vortex.

2024年1月2日 · The radial, meridional and azimuthal components of velocity are therefore \(\dot{r}, \ r \dot{θ}\) and \(r \sin θ \dot{\phi}\) respectively. The acceleration is found by differentiation of Equation \(\ref{3.4.15}\).

恒星的运动在观察方向的速度分量，即径向速度，是一个由行星运动周期所决定的周期信号，其幅度的大小由恒星的质量、行星的质量、恒星与行星的距离、行星轨道平面法线与观测方向的夹角等参数决定。 对于太阳大小的恒星，木星在5个AU距离运动时，恒星径向速度的幅度为12.7m/s；海王星在1个AU距离运动时，恒星径向速度的幅度为1.5m/s；超级地球（5倍的地球质量）在1个AU距离运动时，恒星径向速度的幅度为0.45m/s；而地球在1个AU距离运动时，恒星径向速度的幅 …

With an axial flow, however, it is difficult to find azimuthal velocity even in a concentric annulus filled with a single non-Newtonian fluid because of coupling of velocity components. Without considering a transverse pressure gradient, an analytical solution is possible only for Newtonian fluid in concentric annulus, as expressed by ...

2015年6月9日 · We present azimuthal velocity profiles measured in a Taylor–Couette apparatus, which has been used as a model of stellar and planetary accretion disks. The apparatus has a cylinder radius ratio of ${\it\eta}=0.716$ , an aspect ratio of ${\it\Gamma}=11.74$ , and the plates closing the cylinders in the axial direction are attached to the outer ...

2020年10月21日 · The vorticity in x direction, w_x is calculated with the velocity components v_r and v_theta ( on the plane perpendicular to x) . Similarly for theta component of vorticity, you will use velocity components v_x and v_r and will be on the plane where theta is the normal vector.

Download scientific diagram | Velocity components in azimuthal (azimuthal velocity, left) and equatorial (vertical velocity, right) slices. The contour lines always represent the same...

The azimuthal velocity of each fine scale eddy is normalized by its radius r c and maximum azimuthal velocity, and k θ denotes the wave number in the azimuthal direction. The azimuthal velocity near the center (r < 0.5r c) is dominated by the k θ =2 mode. In this study, phase-average is conducted based on the k θ =2 mode of the azimuthal ...