THUNDERR (Fig 01) originated from two previous EU projects that created a wide wind monitoring network producing an extensive amount of transient wind speed records associated to thunderstorms, pursuing three main Objectives.
Objective I aims at formulating a novel model of thunderstorm outflows by means of thunderstorm detection (WP1), analysis (WP2) and representation (WP3).
WP 1. The existing monitoring network (Task A, Fig 02) was enhanced by an innovative LiDAR scanner (Fig 08) to measure the wind speed up to 14 km. Sub-datasets were created (Task B) to separate different events (Fig 03). Links between thunderstorm records and weather scenarios were identified (Fig 09).
WP 2. A comparison of thunderstorm records, wind tunnel tests (Fig 04), CFD simulations and weather scenarios led to formulate a comprehensive representation of downbursts. Signal records (Task C) were decomposed into samples whose statistical properties were analyzed. A directional decomposition strategy captures outflow shifts (Fig 10). The evolution of the wind speed profile (Fig 11) was carried out using LiDAR profilers. Extensive wind tunnel tests (Task D) at WindEEE Dome (Fig. 12) reproduced thunderstorm outflows. URANS and LES simulations (Fig 13) (Task E) were validated by full-scale and laboratory tests. A link between wind engineering and atmospheric sciences (Task F) was pursued, reconstructing the weather scenario associated to measured thunderstorms. A damage survey after an intense storm traced damage and losses involved (Task G).
WP 3. Thunderstorm modelling (Task H) combines turbulence models, field measures, wind-tunnel tests and CFD simulations. It takes into account stationary downdraft, translation speed and background flow (Fig 14). Extreme wind speed statistics (Task J) confirms that thunderstorms are the main events for return periods above 10 years (Fig 15). A simulator able to reproduce the non-stationary non-Gaussian flow with given parameters have been developed (Task K).
Objective II aims at formulating simple and physically realistic methods to evaluate actions on structures by means of structural analysis (WP4) and impact on constructions (WP5).
WP 4. The monitoring systems of three slender structures have been completed (Task L) (Fig 16). Dynamic analyses (Task M) pursue the creation of a triad of methods to determine the transient response based on real data: response spectrum (Fig 17), time domain simulations, and evolutionary power spectrum. The unique wind loading is separated into two loading conditions for cyclones and thunderstorms (Task N). Transient aerodynamics and possible aeroelastic effects has been analysed (Fig 19).
WP 5. The proposed techniques have being applied to structure test cases (Task O).
Objective III aims at supporting involvement of the scientific community collecting an open-website catalogue of thunderstorm outflows (WP 6) and organizing an International Advanced School (WP 7).
Notwithstanding the sudden and premature passing of the P.I. the research team of the project completed the main objectives of the project, furnishing unprecedented dataset of thunderstorm records open to worldwide scientists, developing original and coherent models of the thunderstorm downburst, proposing cutting edge procedure for evaluating the structural loading and response together with benchmark case history on full scale monitored structures.
