The importance of convective gusts

Abstract

AbstractThis paper examines the practical importance of convective gusts for operators of wind‐sensitive systems and for designers of Wind‐sensitive structures. The mechanics of gusts associated with turbulence (driven by momentum) and convective eddies (driven by buoyancy) are discussed‐Statistical analysis of gusts and gust factors is presented. This shows that extreme gust factors are always produced by the convective mechanism whereas extreme gusts can be produced by either mechanism. Severe convective gusts are shown to have important consequences for operators of Wind‐sensitive systems because they defy precise prediction, they can be isolated in their occurrence, they can occur in quite moderate mean winds and they can be associated with sudden changes of wind direction. Extreme convective gusts are of less importance to designers of wind‐sensitive structures. They are shown to have a relatively small influence on the magnitude of the predicted extreme gusts taken as design criteria for such structures. Nevertheless, there is a significant chance that when such extreme gusts occur, they are produced by the convective mechanism. When this occurs, the predicted aerodynamic effect may be underestimated, to some extent, because of inertial forces which change the nature of the flow and may increase the loading.