Aerodynamics of the Valhalla
The unique shape of the Valhalla was designed to implement some of the aerodynamics used in motor racing, for the design of tents. The roof of a tensile structure is pretty much dome shaped when you remove the conics of the king poles. When the wind acts on a tension structure roof, the windward side receives high pressures and the leeward side exhibits low pressures, offset by the fact that the wind can be 'sticky' and adheres to the roof in what we call 'boundary layer attraction'.
"However, in most flows over surfaces, including those internal and external to the surfaces, viscosity effects are confined to a thin flow region known as the boundary layer. Viscous effects are always significant when fluids flow over solid surfaces or when wakes form behind bodies. The boundary layer is a fundamental concept in aerodynamics and fluid dynamics, as it substantially influences a body’s overall aerodynamic characteristics, including its lift and drag". - Embry Riddle Aeronautical University.
The Bernoulli's principle, which asserts that an increase in the speed of a fluid (air is a fluid in this context) occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy, is the major principle on which the wing is operated.
On the Valhalla the leeward side of the structure has the A frames which form aerodynamic 'duck tails' which disrupt the low pressure vortex created by the wind pressure leaving the surface of the roof. The result is reduced wind load on the structure which has been observed in practice.
While the Valhalla is almost certainly not the first tented structure to use these aerodynamic principles to define a roof shape, it is definitely the largest ever to be built using those theories as first principles. It is to Gearhouse's, and Roger Elton's eternal credit that they allowed Rudi Enos to use these unproven (then) features on a £2,000,000 tensile roof. The structure has repaid that many, many times over the years.
Sketch of the wind flow around a hemisphere placed on the ground - John M. Noble - Army Research Laboratory - Adelphi, United States
On the Valhalla, the windward side has large parts of the roof sweeping down to reduce the direct force on the 8 metre high side walls, while the conics for the king poles break up the air flow going over the roof to reduce the 'boundary layer attraction' that attempts to lift the roof.