Role of Environmental Wind Shear and Helicity in Simulated Tornadoes

底部的旋转筛网和圆柱形室顶部的排气扇的组合使用可以通过角动量守恒产生类似龙卷风的涡流。然而，雷暴环境中垂直风切变的存在会诱发水平涡度，而水平涡度在对流上升气流倾斜时又会诱发垂直涡度。通过用三层有机玻璃导叶取代旋转屏幕，从而模拟与风暴相关的垂直转向风，俄克拉荷马大学的漩涡室现在能够通过涡度倾斜而不是涡度拉伸来模拟漩涡。该项目将允许在涡流室中进行广泛的测量，从而检查环境风切变和螺旋度（涡度矢量和速度矢量的点积）在模拟龙卷风中的作用。

A combined use of a rotating screen at the bottom and an exhaust fan at the top of a cylindrical chamber can produce tornado-like vortices through the conservation of angular momentum. However, the existence of vertical wind shear in a thunderstorm environment can induce horizontal vorticity which in turn induces vertical vorticity when tilted by convective updrafts. By replacing the rotating screen with three tiers of plexiglass guide vanes, thereby simulating the storm-relative, vertically veering winds, the vortex chamber at the University of Oklahoma is now capable of simulating vortices by vorticity tilting instead of vorticity stretching. This project will allow extensive measurements to be made in the vortex chamber and thereby examine the role of environmental wind shear and helicity (the dot product of the vorticity vector and velocity vector) in the simulated tornadoes.