Nonlinear waves in a fluid-filled thin viscoelastic tube

Abstract

In the present paper the propagation property of nonlinear waves in a thin viscoelastic tube filled with incompressible inviscid fluid is studied. The tube is considered to be made of an incompressible isotropic viscoelastic material described by Kelvin-Voigt model. Using the mass conservation and the momentum theorem of the fluid and radial dynamic equilibrium of an element of the tube wall, a set of nonlinear partial differential equations governing the propagation of nonlinear pressure wave in the solid-liquid coupled system is obtained. In the long-wave approximation the nonlinear far-field equations can be derived employing the reductive perturbation technique (RPT). Selecting the exponent α of the perturbation parameter in Gardner-Morikawa transformation according to the order of viscous coefficient η, three kinds of evolution equations with soliton solution, i.e. Korteweg-de Vries (KdV)-Burgers, KdV and Burgers equations are deduced. By means of the method of traveling-wave solution and numerical calculation, the propagation properties of solitary waves corresponding with these evolution equations are analysed in detail. Finally, as a example of practical application, the propagation of pressure pulses in large blood vessels is discussed.

Decomposição de pulsos fotopletismográfico para redução da incerteza do Tempo de Trânsito

“…Esse resultado indica que PDA a partir da função secante hiperbólica prevê que o PTT em pulsos subsequentes são similares, como esperado, já com a função gaussiana, os pulsos subsequentes têm alta flutuação nos valores de PTT de um pulso para outro. Nossa hipótese é que a função secante hiperbólica é mais adequada, pois, além de ter maior estabilidade é solução física para ondas em fluidos (27).…”

“…Dentre as funções já testadas na literatura, somente a função Rayleigh representa uma onda física, porém é a solução para uma onda propagante na superfície de águas rasas comparadas com o comprimento da onda. Aqui, propomos estudar a função secante hiperbólica (sech), que é uma solução física para pulsos propagantes e sólitons em tubos viscoelásticos preenchidos por fluido (27).…”

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