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Modelos de esteira oscilante
A dinâmica de uma estrutura esbelta sujeita a um escoamento transverso
È um problema que se enquadra no contexto das Vibrações Induzidas por Vórtices (VIV). A sua abordagem recorre geralmente a modelos semi-empÌricos tais como, os modelos de esteira oscilante, cujas soluções permitem descrever a dinâmica referida. São compostos por duas equações diferenciais acopladas:
uma equação diferencial ão linear de 2ª ordem que descreve a esteira oscilante, normalmente a equação de Van de Pol, acoplada a uma equação diferencial linear de 2 a ordem que descreve o comportamento da estrutura esbelta. Neste trabalho, várias formulações para os modelos de esteira oscilante são apresentadas e discutidas. Um estudo numérico das respostas vibratórias da esteira e da estrutura para o acoplamento em aceleração, em velocidade e em deslocamento, separadamente e também para uma combinação dos
três acoplamentos, È apresentado, para esta última formulação, recorre-se ainda a dados experimentais e técnica de Simulação do Recozimento, para calibração dos parâmetros desconhecidos. O desempenho de cada formulação é apresentado e discutido.
Wake oscillator mo dels The dynamics of a slender structure sub jected to a transverse áow is a complex problem that Öts in the context of Vortex-Induced Vibrations (VIV). The understanding of such dynamics is of great interest in the design and maintenance of numerous systems with great economic impact in areas of civil engineering and maritime structures among many others. The study of these phenomena generally involves the use of semi-empirical mo dels such as the wake oscillator mo dels whose solutions can describ e this dynamics. Wake oscillator mo dels consist of two coupled di§erential equations: a second-order nonlinear di§erential equation (typically the Van der Pol equation) describing the wake, coupled with a second order linear di§erential equation describing the b ehaviour of the slender structure. In this work, di§erent formulations for the wake oscillator mo dels are presented and discussed. Based on numerical simulations, the vibratory resp onse of b oth wake and structure, is analyzed. One approach consists in study each coupling - acceleration, velo city and displacement - separately. In the other approach, a combination of these three couplings is presented. In order to deal with the unknown parameters that emerge from this last approach, the Simulated Annealing metho d was implemented, based on exp erimental data. Each formulation p erformance for the wake oscillator mo dels is presented and discussed
Wake oscillator mo dels The dynamics of a slender structure sub jected to a transverse áow is a complex problem that Öts in the context of Vortex-Induced Vibrations (VIV). The understanding of such dynamics is of great interest in the design and maintenance of numerous systems with great economic impact in areas of civil engineering and maritime structures among many others. The study of these phenomena generally involves the use of semi-empirical mo dels such as the wake oscillator mo dels whose solutions can describ e this dynamics. Wake oscillator mo dels consist of two coupled di§erential equations: a second-order nonlinear di§erential equation (typically the Van der Pol equation) describing the wake, coupled with a second order linear di§erential equation describing the b ehaviour of the slender structure. In this work, di§erent formulations for the wake oscillator mo dels are presented and discussed. Based on numerical simulations, the vibratory resp onse of b oth wake and structure, is analyzed. One approach consists in study each coupling - acceleration, velo city and displacement - separately. In the other approach, a combination of these three couplings is presented. In order to deal with the unknown parameters that emerge from this last approach, the Simulated Annealing metho d was implemented, based on exp erimental data. Each formulation p erformance for the wake oscillator mo dels is presented and discussed
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Vibrações induzidas por vórtices (VIV) modelos de esteira oscilante