Comparison Between Thermal Conductivity Models on Heat Transfer in Power-Law Non-Newtonian Fluids

Abstract

This paper endeavors to complete a numerical research on forced convection steady heat transfer in power-law non-Newtonian fluids in a circle duct. Incompressible, laminar fluids are to be studied with a uniform wall temperature. A hydrodynamic entrance length is neglected which allows establishing a fully developed flow. The energy equation is solved by using a LU decomposition coupled with control volume technique based on finite difference method. Four thermal conductivity models are adopted in this paper, that is, constant thermal conductivity model, linear thermal conductivity varying with temperature, thermal conductivity varying as a function of velocity gradient, and thermal conductivity varying as a function of temperature gradient. The results are compared with each other and the physical characteristics for values of parameters are also discussed in details. It is shown that the heat transfer behaviors are strongly depending on the power-law index in all models. Comparisons of temperature and local Nusselt number between models are made. It reveals the increasing values of thermal conductivity parameter result in increasing the local Nusselt number when the thermal conductivity is a linear one. Furthermore, there is obvious difference in the local Nusselt number between the constant model and the power-law velocity-dependent model, but Nusselt number varies little from the constant model to the power-law temperature-dependent model.

Marangoni mixed convection flow with Joule heating and nonlinear radiation

“…Marangoni convection radiative flow and heat transfer in pseudoplastic nanofluids by a temperature gradient has been reported by Lin et al 13 Lin et al 14 examined MHD thin film flow and heat transfer of power law fluid by an unsteady stretching surface. Li et al 15 numerical analyzed forced convection steady flow with heat transfer in power-law non-Newtonian fluids through a circle duct.…”

MHD pseudo-plastic nanofluid unsteady flow and heat transfer in a finite thin film over stretching surface with internal heat generation

“…The nanofluid is assumed incompressible and the flow is laminar, the base fluid and the nanoparticles are in thermal equilibrium and that no slippage occurs between them. Under these assumptions, the governing conservation equations of mass, momentum and energy in unsteady state can be expressed as [13][14][15][16][17][18][19][20][21][22][41][42][43][44][45][46][47][48][49][50][51][52] @u @x þ @v @y…”

“…The effects of power law viscosity on a temperature field are taken into account with a modified Fourier's law proposed by assuming that the temperature field is similar to the velocity field [41][42][43][44][45][46][47][48][49][50][51][52]. External magnetic field and internal heating effects are considered.…”

Marangoni abnormal convection heat transfer of power-law fluid driven by temperature gradient in porous medium with heat generation

“…Zheng et al [10,11] proposed a new heat transfer model by assuming that the temperature field is similar to the velocity field, the effects of power-law viscosity on heat conductivity are analyzed. In addition, Li et al [12][13][14] numerically simulated the phenomenon of flow, heat transfer and diffusion of the power-law fluid in the circular tube. Lin et al [15][16][17][18] studied the heat and mass transfer of steady laminar Marangoni convection driven by surface tension gradient using numerical method.…”