Abstract

OBJECTIVES To establish analytical expressions for the thickness of laminar sublayer and turbulent boundary layer and friction coefficients of turbulent purely viscous non-Newtonian pipe flows as the function of apparent Reynolds number. METHODS/STATISTICAL ANALYSIS The turbulent boundary layer concepts are adopted to solve the problem of non-Newtonian flow through a pipe. The Blasius approach is considered in solving laminar sublayer and turbulent core regions which are dealt separately. Further, the influence of polymer concentration or power law index on turbulent flow behavior along with friction coefficients is are studied. Further simulation is performed using Ansys Fluent v14.5 to validate the results obtained from the theoretical analysis. FINDINGS The normalized thicknesses of laminar sublayer and turbulent core are predicted theoretically in terms of apparent Reynolds number, Rea, and power law index, n. From the present analysis, it is found that the normalized thickness for laminar sublayer is 12.25. The variation of fluid viscosity at laminar sublayer with respect to the concentration of polymer and Reynolds number are studied. The thicknesses and velocities at laminar sublayer are found from present analysis and the same compared with the Newtonian results. The range of apparent Reynolds number considered for present work is 10000-50000 and concentration range of polymer is 0.5 to 2.0 wt%. The expression of friction coefficients obtained from analysis yielded results which compared with the empirical equations available in literature and found to be in good agreement. The reduction in friction coefficients is are observed with increase in the concentration of polymer. Further drag reduction also validated in comparison with Newtonian fluid flows at given Reynolds number. The present results are also in good agreement with simulation results obtained from AnsysFluent v14.5. APPLICATION / IMPROVEMENTS The present work finds applications in various fields like chemical, pharmaceutical, food industries and in defense.

Authors and Affiliations