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There is a strong real-time coupling between seabed topography and wave field, current field and wind field in shallow water area. The existing analysis model cannot directly consider the influence factors of seabed, and it is more difficult to explain the unsteady evolution mechanism of the coupling field between typical seabed topography and wave, shear flow and gradient wind. Based on the secondary development of STAR-CCM+platform, the shallow sea wind-wave-current numerical pool is constructed under four typical seabed landform conditions: seabed plain, seabed slope, trough, and flat landform. The multi-layer particle velocity coupling method is proposed and the multi-layer wind-wave-current coupling model is established. The wind-wave-current decoupling is realized at the initial time. The temporal and spatial evolution laws of wave field, current field, and wind field in different seabed topographies are compared and analyzed. The principal component analysis method is introduced to evaluate the unsteady effect of wind-wave-current in various typical seabed topographies, and the unsteady evaluation index of the whole life cycle of the wind-wave-current-seabed coupling field is established. The results show that the multi-layer wind-wave-current coupling model can more truly reflect the influence of vertical wind speed and uneven velocity distribution on wave field. The seabed topography can lead to a multi-stage time-history distribution of wave field in the evolution process. The flat topography, submarine slope, and trough conditions are divided into wave surface surge, attenuation, and stability stages. The submarine plain conditions are divided into external breaking wave, internal breaking wave, and climbing stage. The evolution of the current field presents a multi-stage spatial distribution, and the seabed leads to the formation of multi-vortex accumulation or multi-vortex coexistence in the current field. The coupling evolution of wind-wave-current-seabed has an amplification effect on the wind profile index, and positive relationship between seabed height and wind profile coefficient. The end-stage unsteady evaluation indices of flat landform, submarine plain, submarine slope, and trough are 0.268, 4.612, 0.672, and 0.926, respectively.

ln order to accurately simulate 3-D wind field of wind turbines, taking the NH1500 wind turbine researched by Nanjing University of Aeronautics and Astronautics as an example, the exponential model for changing height, the undercurrent model for tower shadow effect and the eddy viscosity model for wake effect from upstream wind turbine are used to modify the steady wind. Then based on the modified Von Karman wind speed spectrum model, the incoming wind speed time history is simulated by the harmony superposition method. Finally the 3-D wind field considering the rotational effect and blade-tower interaction effect is obtained with the modified blade element momentum theory. The external interference factors and itself characteristics are fully considered to improve the accuracy of wind field simulation. The results show that the proposed algorithm is of high accuracy, which can be used to simulate 3-D wind field of wind turbines under given wind condition. [ABSTRACT FROM AUTHOR]

Based on grey GM(1,1) model and BP artificial neural network, the grey-neural network joint model is established, which is used to predict the displacement and wind induced coefficients for large cooling towers. Using the joint model, the influence caused by little raw data is overcome. Furthermore the self-adaptability and predicting precision for wind-induced responses of large cooling towers are enhanced. Through comparative analysis of the wind-induced responses of domestic large hyperbolic cooling tower in aero-elastic model wind tunnel test, it can be found that the prediction results of wind-induced responses and wind vibration coefficients are in good agreement with the experimental results, which shows good validity and stability of the model, and then input parameters of refined research on wind induced response are predicted. The proposed method provide a new and effective idea for the refined research on wind effects of large cooling towers. [ABSTRACT FROM AUTHOR]

Aiming at the limitations of total fluctuating wind-induced response with combination of background and resonant components using square root of the sum of squares (SRSS) method, the theoretical combination formulas of fluctuating wind-induced responses and ESWLs were derived based on structural dynamics and random vibration theory. The refined analysis method is firstly presented by consistent coupled formula to compensate the coupling component between background and resonant modes. The proposed procedure avoids the integration process of calculating elastic restoring force and completely considers the modal coupling effects, which can be used to calculate the ESWL for any complex structures. The calculation of wind-induced response of steel grid roof structure of a large museum demonstrates the effectiveness and accuracy of the present approach. Finally the characteristics of windinduced response are obtained. This paper proposes a new way of analyzing characteristics of wind-induced responses and mechanisms of actions. [ABSTRACT FROM AUTHOR]