Numerical Simulation Of Flow Around Vibrating 2-D Roofs

Membrane structures, which are lightweight and flexible, are widely used as space structures. It is because of such features that the wind load is dominant to membrane structures. Under the load of the wind, they will be subject to large deformation which will affect the flow field. This phenomenon is so-called'fluid-structure interaction'(FSI). There are seldom studies on FSI which is caused by membrane structures and the wind. In the numerical simulation of FSI, it is particularly difficult to solve problems of FSI, because the fluid domain (CFD), the structural domain (CSD) and the exchange of data between them are involved. In this paper, in order to study the influence of the vibration of the roof with or without enclosed walls to the structure and the flow field, the problem of fluid-structure interaction was transformed to that of the moving boundary. Since any form of the vibration of the roof can be seen as composition of simple harmonic motion, in this paper, taking roofs with and without enclosed walls as examples, the effects of several factors, such as vibration amplitude, frequency of the vibration and vibration waveform were studied to tentatively investigate the aerodynamic characteristics of the roof and the characteristics of the wind field and some preliminary conclusions were obtained.Firstly, in this paper, the basic methods of CFD numerical simulation and dynamic mesh were introduced. Then the applicability of turbulence model and dynamic mesh updating scheme was discussed. In order to contrast various turbulence models and to select the most appropriate turbulence model, a numerical simulation of flow around a square cylinder was carried out. The results showed that large eddy simulation (LES) approach could give results in accordance with the test. Another numerical example of a transversely oscillating circular cylinder was practiced to vertify the feasibility of the moving mesh updating method. The results showed that with local remeshing method the conclusions were consistent with some relative literature.Secondly, according to the above research results, with appropriate turbulence model and dynamic mesh updating method, a numerical example of a vibrating roof with enclosed walls was simulated. In the uniform flow, the effects of several factors, such as vibration amplitude, frequency of the vibration and vibration waveform were studied to tentatively investigate the aerodynamic characteristics of the roof. The results showed that the roof was unfavorable when large vibration amplitude, fast frequency of the vibration or complex vibration waveform was obtained.Lastly, a numerical example of a vibration roof without enclosed walls was simulated. In the uniform flow, the effects of several factors, such as vibration waveform, frequency of the vibration and vibration amplitude were studied to investigate the aerodynamic characteristics of the roof. The results showed that the roof was unfavorable when large vibration amplitude, fast frequency of the vibration or simple vibration waveform was obtained.