There are many examples of flows around flexible surfaces in which there is a strong interaction between the surface shape and the flow. Examples include the flow around sails, parawings, inflated lenticular wings, air supported structures and water-inflated membrane dams. The present paper has presented a method for solving compliant-surface problems in which there is a strong interdependence of the surface shape and the flow. To the authors' knowledge, this represents the first implicit CFD predictions for this class of problem. Predictions have been reported for two problems, for which measurements have been provided by Newman et al.: flow ober a sail, and flow around an inflated building. The present predictions show that reasonably accurate 2D predictions of the fluid flow and of the tension within the material are possible. The extension of the method to 3D is also possible, but non-trivial. The factor that arose from this study, that the authors had not fully anticipated, is the additional demands placed on the turbulence model. For flows involving fixed surfaces, or surfaces with a prescribed motion, inaccuracies in the turbulence model result in incorrect surface stresses, separation points, and size of recirculation zones. When the surface is compliant, these modelling errors feed back to change the surface shape, which affects the mean flow, and which leads to flow structures that may depart even further from those observed. The compliant surface is therefore another mechanism, and a powerful one, by which turbulent transport feeds back to alter the mean flow.
Prediction of compliant-surface flows
Vorhersage von Strömungen um flexible Oberflächen
1996
8 Seiten, 11 Bilder, 12 Quellen
Conference paper
English
Oberfläche , Flexibilität , Umströmung , Vorhersage , Membran , Bewegungsgleichung , Form (Gestalt) , Wechselwirkung , Strömungsmechanik , Theorie , Messung , Gebäude , Aufblasen , Turbulenz , Modell , Oberflächenspannung , Rückkopplung
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