Abstract

Laminar two-dimensional natural convection boundary-layer flow of non-Newtonian fluids along a horizontal circular cylinder with uniform surface heat flux has been studied using a modified power-law viscosity model. In this model, there are no unrealistic limits of zero or infinite viscosity; consequently, no irremovable singularities are introduced into boundary-layer formulation for such fluids. Therefore, the boundary-layer equations can be solved numerically by using marching order implicit finite difference method with double sweep technique. Numerical results are presented for the case of shear thinning as well as shear thickening fluids in terms of the fluid velocity and temperature distributions, shear stresses, and rate of heat transfer in terms of the local skin friction coefficient and local Nusselt number, respectively.

Highlights

  • Natural convection laminar flow of non-Newtonian powerlaw fluids from a horizontal circular cylinder with uniform heat flux presents an important role in numerous engineering applications that are related to pseudoplastic fluids

  • The pseudoplastic fluid is characterized by a constant viscosity at very low shear rates, a viscosity which decreases with shear rate at intermediate shear rates and an apparently constant viscosity at very high shear rate

  • The boundary-layer formulation along with an isothermal horizontal circular cylinder is described and numerically solved for non-Newtonian fluid in Bhowmick et al [20] for the case of shear-thinning as well as shear thickening fluids. The behavior of both shear-thinning and shear thickening fluids on the natural convection laminar flow with uniform heat flux along a horizontal circular cylinder is studied by choosing the power-law index as (n = 0.6, 0.8, 1.0, 1.2, 1.4) to fully demonstrate the performance of various non-Newtonian fluids

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Summary

Introduction

Natural convection laminar flow of non-Newtonian powerlaw fluids from a horizontal circular cylinder with uniform heat flux presents an important role in numerous engineering applications that are related to pseudoplastic fluids. The boundary-layer formulation on a flat plate is described and numerically solved for non-Newtonian fluid in Yao and Molla [16, 17], and the associated heat transfer for two different. The boundary-layer formulation along with an isothermal horizontal circular cylinder is described and numerically solved for non-Newtonian fluid in Bhowmick et al [20] for the case of shear-thinning as well as shear thickening fluids In this investigation, the behavior of both shear-thinning and shear thickening fluids on the natural convection laminar flow with uniform heat flux along a horizontal circular cylinder is studied by choosing the power-law index as (n = 0.6, 0.8, 1.0, 1.2, 1.4) to fully demonstrate the performance of various non-Newtonian fluids. The results of our parametric study in the paper can provide the necessary database that a simple interpolation can be used to find approximate heat transfer rates and wall shear stresses for any non-Newtonian fluid from our tables

Formulation of the Problem
Result and Discussion
Conclusions

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