Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
MODELLING OF FLUID TRANSIENTS IN VISCOELASTIC COMPLIANT PIPES
Submission Author:
DOUGLAS MONTEIRO ANDRADE , RJ , Brazil
Co-Authors:
DOUGLAS MONTEIRO ANDRADE, Felipe Bastos de Freitas Rachid
Presenter: DOUGLAS MONTEIRO ANDRADE
doi://10.26678/ABCM.COBEM2021.COB2021-0540
Abstract
In industry, daily operations as valve maneuvers generate unsteady pipe flows. The dynamics of such flows is governed by a cyclic passage of a wavefront which is responsible for local pressure surges. These pressure traces subject the compliant pipe to stresses that are greater than those found under steady-state regime. As those fluctuations depend not only on the fluid and the nature of the flow but also on the mechanical response of the material with which the tubes are made, the accurate analysis of these problems is conditioned to the joint description of all these aspects. This paper arises to present a thermodynamic consistent model capable to handle transient flows in viscoelastic compliant pipes. To accomplish this goal, first, a robust model of unsteady friction on the fluid is applied as the basic framework, afterward, the tube viscoelasticity is advanced invoking a constitutive theory with a strong thermodynamic foundation. Such an approach allows the computation of the rates of dissipation on fluid and on the solid distinctly and accurately. The proposed model results in a quasi-linear hyperbolic system of partial differential equations whose solution is approximated by using the method of characteristics. When compared with experimental data, numerical responses of the present model are found to be largely more accurate than the one which disregards the anelastic nature of the tube. This fact is partially explained by the fact of the rates of energy dissipation presented by the fluid and tube to be at the same order of magnitude throughout the transient.
Keywords
unsteady friction, viscoelasticity, Internal Variables, energy dissipation
