Wind Gusts
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Recent papers in Wind Gusts
South Biscay coastally trapped disturbances known as gales (galernas, enbatak, galarrenak, bruilartak) are adverse phenomena that send along the Cantabrian and Basque Coast a narrow jet of sudden and violent gusts of wind that do not... more
South Biscay coastally trapped disturbances known as gales (galernas, enbatak, galarrenak, bruilartak) are adverse phenomena that send along the Cantabrian and Basque Coast a narrow jet of sudden and violent gusts of wind that do not follow a hydrostatic balance parameterization, being faster, stronger and of a Western-North-Westerly component, and accelerate as they rush Eastward enduring their speed and intensity. These gales run the coast line from West to East strengthening in Eastern Cantabrian Seashore line from May to October. Well known by the death people and disasters induced 7 , Gales are dangerous for the difficultness in predicting them: both the direction of the violent gusts and their displacement along the coast line are ageostrophic, that is, perpendicular to the mesoescalar pressure gradient. In this paper the pure ageostrophic gale happened on the noon of 2013 July 31st is analysed; more than for its strength-the wind gusts only raised to 40 km h-1-it is important for the scholastic behaviour of atmospheric and oceanographic variable as for the absolute independence from any other phenomenon whatsoever (i.e. Cold Front)
The paper addresses the simulation of turbulent wind gusts hitting rigid and flexible structures. The purpose is to show that such kind of complex fluid-structure interaction (FSI) problems can be simulated by high-fidelity numerical... more
The paper addresses the simulation of turbulent wind gusts hitting rigid and flexible structures. The purpose is to show that such kind of complex fluid-structure interaction (FSI) problems can be simulated by high-fidelity numerical techniques with reasonable computational effort. The main ingredients required for this objective are an efficient method to inject wind gusts within the computational domain by the application of a recently developed source-term formulation, an equally effective method to prescribe the incoming turbulent flow and last but not least a reliable FSI simulation methodology to predict coupled problems based on a partitioned solution approach combining an LES fluid solver with a FEM/IGA solver for the structure. The present application is concerned with a rigid and a membranous hemisphere installed in a turbulent boundary layer and impacted by wind gusts of different strength. The methodology suggested allows to inject the gusts in close vicinity of the object of interest, which is typically well resolved. Therefore, the launch and transport of the wind gust can be realized without visible numerical dissipation and without large computational effort. The effect of the gusts on the flow field, the resulting forces on the structure and the corresponding deformations in case of the flexible structure are analyzed in detail. A comparison between the rigid and the flexible case makes it possible to work out the direct reaction of the deformations on the force histories during the impact. Furthermore, in case of the flexible structure the temporal relationships between local or global force developments and the local deformations are evaluated. Such predictions pinpoint the areas of high stresses and strains, where the material is susceptible to failure.
The objective of the present paper is to revisit two well-known wind gust injection methods in a consistent manner and to assess their performance based on different application cases. These are the field velocity method (FVM) and the... more
The objective of the present paper is to revisit two well-known wind gust injection methods in a consistent manner and to assess their performance based on different application cases. These are the field velocity method (FVM) and the split velocity method (SVM). For this purpose, both methods are consistently derived pointing out the link to the Arbitrary Lagrangian Eulerian formulation and the geometric conservation law. Furthermore, the differences between FVM and SVM are worked out and the advantages and disadvantages are compared. Based on a well-known test case considering a vertical gust hitting a plate and a newly developed case taking additionally a horizontal gust into account, the methods are evaluated and the deviations resulting from the disregard of the feedback effect in FVM are assessed. The results show that the deviations between the predictions by FVM and SVM are more pronounced for the horizontal gust justifying the introduction of this new test case. The main reason is that the additional source term in SVM responsible for the feedback effect of the surrounding flow on the gust itself nearly vanishes for the vertical gust, whereas it has a significant impact on the flow field and the resulting drag and lift coefficients for the horizontal gust. Furthermore, the correct formulation of the viscous stress tensor relying on the total velocity as done in case of SVM plays an important role, but is found to be negligible for the chosen Reynolds number of the present test cases. The study reveals that SVM is capable of delivering physical results in contradiction to FVM. It paves the way for investigating further complex gust configurations (e.g., inclined gusts) and practical applications towards coupled fluid-structure interaction simulations of engineering structures impacted by wind gusts.
The present paper deals with the modeling of wind gusts within large-eddy simulations (LES). The method relies on a source-term approach and is evaluated based on a simple CFD case and a challenging fluid-structure interaction (FSI) case... more
The present paper deals with the modeling of wind gusts within large-eddy simulations (LES). The method relies on a source-term approach and is evaluated based on a simple CFD case and a challenging fluid-structure interaction (FSI) case of a membranous hemisphere in a turbulent boundary layer.