Purely tangential flow of a PTT- viscoelastic fluid within a concentric annulus

  M Mirzazadeh, M P Escudier, F Rashidi, S.H Hashemabadi




  An analytical solution is presented for the steady state, purely tangential flow of a viscoelastic fluid obeying the Phan-Thien-Tanner (PTT) constitutive equation in a concentric annulus with relative cylinder rotation. The influence on the velocity distribution and fRe of the Weissenberg number, aspect ratio and an elongational parameter are investigated for two combinations of inner and outer cylinder rotation . The results show that the differences between the radial location of the minimum velocity and of the critical angular velocity compared with their Newtonian counterparts increase when the fluid elasticity increases. T he results also show that decreases with increasing Weissenberg number, radius ratio and the elongational parameter in the case of inner cylinder rotation. In contrast, increases with increasing radius ratio when the outer cylinder is rotating while the inner cylinder is at rest.

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