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Mechanics in Engineering ›› 2004, Vol. 26 ›› Issue (2): 0-0.doi: 10.6052/1000-0879-2003-027

• Education Study •    

DESCRIPTION OF VISCOELASTIC PROPERTIES FOR A BOGER FLUID BY USING KBKZ-TYPE CONSTITUTIVE EQUATIONS

  

  • Received:2003-01-21 Revised:2003-07-01 Online:2004-04-10 Published:2004-04-10

Abstract: Four KBKZ integral-type constitutive equations, including Wagner model, PSM model, 2e model and 3r model proposed by the authors, were used in the paper to describe the viscoelastic characteristics of a Boger fluid. The least square approximation was adopted to fit $G'$ and $G''$ to obtain the relaxation spectrum of the fluid, and the nonlinear programming method was employed to fit $N_{1}$ to obtain the parameter values in the damping function of the four models. The results show that the four models can characterize the rheological properties of the Boger fluid precisely. Either Wagner model or PSM model is a good choice for characterizing the viscoelastic properties of Boger fluid, due to its simplicity.

Key words: Boger fluid, viscoelastic properties, integral-type KBKZ