A rack and system for cooling computing devices such as in a data center is disclosed. In one embodiment, the rack supports a plurality of computing devices and comprises a plurality of planar annular sector or trapezoidal shelves, each having one or more positions for holding computing devices. A number of vertical supports may hold the shelves in a vertically spaced arrangement, and an air barrier may be affixed to the rack. The air barrier may have openings for the computing devices to permit exhaust air to flow through the air barrier into a hot aisle. The rack maybe configured to be connected to other similar racks to form a vertical annular hyperboloid or a vertical hyperbolic annular paraboloid, and the computing devices may be installed to discharge exhaust at an angle relative to a centerline of the vertical annular hyperboloid or a vertical hyperbolic annular paraboloid to improve airflow.