Abstract: Adding of solid particles or bubbles to the carrier liquid can modify the laminar-turbulent transition. Fine particles enhance the effective viscosity of the slurry and this may by expected to delay the transition to turbulence. The paper presents experimental data of slurry flow of fine particles with the mean particle diameter of 10 [mu]m in horizontal circular pipe. Rheological measurements allow assuming that the slurry can be approximated by the Bingham model. By using the different approach towards calculation of the Reynolds number, the measured and predicted velocity profiles of Bingham slurry were compared to see quantitative difference in interpretation of the laminar-turbulent transition. For the slurry flow of fine particles it was shown that the laminar-turbulent transition exists for higher Reynolds number than we expect. In case of the laminar flow the velocity profiles possess sheared and unsheared part, while in the turbulent flow the unsheared part does not exist. The results of the research are presented as figures and conclusions.
B I B L I O G R A F I A[1] SHOOK C.A. AND ROCO M.C.: Slurry Flow: Principles and Practice, Butterworth-Heinemann, Boston 1991.
[2] NOURI J.M., WHITELAW J.H., YIANNESKIS M.: Particle motion and turbulence in dense two-phase flows, Int. J. Multiphase Flow, 13(1987), 729-739.
[3] NOURI J.M. AND WHITELAW J.H.: Particle velocity characteristics of dilute to moderately dense suspension flows in stirred reactors, Int. J. Multiphase Flow, 18(1992), No. 1, 21-33.
[4] MAVROS P.: Flow visualisation in stirred vessels. A review of experimental techniques, Chem. Eng. Res. Dev., 79(2001), 113-127.
[5] PULLUM L. AND GRAHAM L.J.W.: The use of magnetic Resonance imaging (MRI) to probe complex hybrid suspension flows, 10th Int. Conf. on Transport and Sedimentation of Solid Particles, Sc. Papers of the agricultural Academy of Wrocław, Wrocław, Poland, 1(2000), No. 382, 421-434.
[6] CHHABRA R. AND RCHARDSON J.F.: Non-Newtonian Flow in the Process Industries, Butterworth-Heinemann, Oxford, 1999.
[7] MATAS J.P., MORRIS J.F., GUAZZELLI E.: transition to turbulence in particulate pipe flow, Phys. Rev. Lett., 90(2003), 014501.
[8] SUNDARESAN S., EATON J., KOCH D.L., OTTINO J.M.: Appendix 2: Report of Study Group on Disperse Flow, Int. J. Multiphase Flow, 29(2003), 1069-1087.
[9] MICHAELS A.S. AND BOLGER J.C.: Settling Rates and Sediment Volumes of Flocculated Kaolin Suspensions, J. Industrial & Engineering Chemistry Fundamentals, 1(1962), No. 1, 24-33.
[10] MICHAELS A.S. AND BOLGER J.C.: The plastic flow behavior of flocculated kaolin suspensions, J. Industrial & Engineering Chemistry Fundamentals, 1(1962), No. 3, 153-162.
[11] THOMAS D.G.: Transport characteristics of suspensions VII: Relation of hindered-settling floc characteristics to rheological properties, AIChE, 9(1963), No. 3, 310-316.
[12] WILSON K.C. AND THOMAS A.D.: A new analysis of the turbulent flow of non-Newtonian fluids, Int. J. of Chem. Eng., 63(198), 539-546.
[13] SQUIRES K.D. AND EATON J.K.: Preferential concentration of particles by turbulence, Phys. Fluids, A3(1991), 1169-1178.
[14] RYAN N.W. AND JOHNSON M.M.: Transition from laminar to turbulent flow in pipes. AIChE J., 5(1959), 433-435.
[15] HANKS R.W.: Course notes. Hydraulic design for flow complex fluids, Richard W. Hanks Associates, Inc. Orem, Utah, USA, 1981.
[16] SLATTER P.T. AND WASP E.J.: The laminar/turbulent transition on large pipes, 10th Int. Con. Transport and Sedimentation of Solid Particles, Wroclaw 2000, Sc. Papers of the Agricultural Academy of Wrocław, 1(2000), No. 382, 389-399.
[17] BARTOSIK A.: Experiments on turbulent flow of fine dispersive hydro-mixture, 14th Nat. Conf. Fluid Mechanics, Polish Academy of Sciences, Lodz, Poland, 2000, Sc. Papers of Lodz University of Technology, Cieplne Maszyny Przepływowe - Turbomachinery, Łódź, 2000, No. 851, 289-296.
[18] BARTOSIK A.: Velocity distribution measurements in Bingham slurry flow, 10th Int. Conf. Transport and Sedimentation of Solid Particles, Wrocław, September 2000, Sc. Papers of the Agricultural Academy of Wrocław, Poland, 292000), No. 382, 571-579.
[19] AHMED A., ALEXANDROU A.N.: Processing of semisolid materials using a shear-thickening Bingham fluid model, [in:] Proc. of the ASME Fluids Engineering Division Summer Meeting, FED, New York, 179(1994), 83.
[20] BINGHAM E.C.: Fluidity and Plasticity, McGraw-Hill, New York 1922.
[21] WILSON C.C.: Computational rheology for pipeline an annular flow, Butterworth-Heinemann, Boston 2001.
[22] HAO Z. AND ZHENGHAI R.: Discussion on law of resistance of hyperconcentration flow in open channels, Scientia Sinica, 25(1982), Ser. A, 12. 
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