### Abstract

The unsteady flows of Burgers’ fluid with fractional derivatives model, through a circular cylinder, is studied by means of the Laplace and finite Hankel transforms. The motion is produced by the cylinder that at the initial moment begins to rotate around its axis with an angular velocity Ω*t*, and to slide along the same axis with linear velocity *Ut*. The solutions that have been obtained, presented in series form in terms of the generalized *G* _{ a,b,c }(•, *t*) functions, satisfy all imposed initial and boundary conditions. Moreover, the corresponding solutions for fractionalized Oldroyd-B, Maxwell and second grade fluids appear as special cases of the present results. Furthermore, the solutions for ordinary Burgers’, Oldroyd-B, Maxwell, second grade and Newtonian performing the same motion, are also obtained as special cases of general solutions by substituting fractional parameters α = β = 1. Finally, the influence of the pertinent parameters on the fluid motion, as well as a comparison among models, is shown by graphical illustrations.

Received 19 December 2011
Accepted 11 February 2012
Published online 07 March 2012

Acknowledgments:
The authors would like to express their sincere gratitude to the referees for their careful assessment and fruitful remarks and suggestions regarding the initial version of the manuscript.

The author Muhammad Jamil highly thankful and grateful to the Abdus Salam School of Mathematical Sciences, GC University, Lahore, Pakistan; Department of Mathematics, NED University of Engineering & Technology, Karachi-75270, Pakistan and also Higher Education Commission of Pakistan for generous support and facilitating this research work.

The author Najeeb Alam Khan is highly thankful and grateful to the Dean of Faculty of Sciences, University of Karachi, Karachi-75270, Pakistan for supporting and facilitating this research work.

Article outline:

I. INTRODUCTION
II. DEVELOPMENT OF THE GOVERNING EQUATIONS
III. HELICAL FLOWS OF FRACTIONALIZED BURGERS’ FLUID
A. Calculation of the velocity field
B. Calculation of shear stresses
IV. THE SPECIAL CASES
A. Helical flows of ordinary Burgers’ fluid
B. Helical flows of fractionalized Oldroyd-B fluid
C. Helical flows of ordinary Oldroyd-B fluid
D. Helical flows of fractionalized Maxwell fluid
E. Helical flows of ordinary Maxwell fluid
F. Helical flows of fractionalized second grade fluid
G. Helical flows of ordinary second grade fluid
H. Helical flows of Newtonian fluid
V. NUMERICAL RESULTS AND CONCLUSIONS

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