Abstract
Single and double impinging jets heat transfer of non-Newtonian power law nanofluid on a partly curved surface under the inclined magnetic field effects is analyzed with finite element method. The numerical work is performed for various values of Reynolds number (Re, between 100 and 300), Hartmann number (Ha, between 0 and 10), magnetic field inclination (γ, between 0 and 90), curved wall aspect ratio (AR, between 01. and 1.2), power law index (n, between 0.8 and 1.2), nanoparticle volume fraction (ϕ, between 0 and 0.04) and particle size in nm (dp, between 20 and 80). The amount of rise in average Nusselt (Nu) number with Re number depends upon the power law index while the discrepancy between the Newtonian fluid case becomes higher with higher values of power law indices. As compared to case with n = 1, discrepancy in the average Nu number are obtained as −38% and 71.5% for cases with n = 0.8 and n = 1.2. The magnetic field strength and inclination can be used to control the size and number or vortices. As magnetic field is imposed at the higher strength, the average Nu reduces by about 26.6% and 7.5% for single and double jets with n greater than 1 while it increases by about 4.78% and 12.58% with n less than 1. The inclination of magnetic field also plays an important role on the amount of enhancement in the average Nu number for different n values. The aspect ratio of the curved wall affects the flow field slightly while the average Nu variation becomes 5%. Average Nu number increases with higher solid particle volume fraction and with smaller particle size. At the highest particle size, it is increased by about 14%. There is 7% variation in the average Nu number when cases with lowest and highest particle size are compared. Finally, convective heat transfer performance modeling with four inputs and one output is successfully obtained by using Adaptive Neuro-Fuzzy Interface System (ANFIS) which provides fast and accurate prediction results.
Highlights
The numerical analysis is performed for different values of Reynolds number (Re) number (100 ≤ Re ≤ 300), Hartmann number (0 ≤ Ha ≤ 10), inclination of magnetic field (MF) (0 ≤ γ ≤ 90), aspect ratio of the curved surface (0.1 ≤ AR ≤ 1.20), power law index (0.8 ≤ n ≤ 1.2), nanoparticle volume fraction (0 ≤ φ ≤ 0.04) and particle size in nm (20 ≤ dp ≤ 80)
Convective heat transfer (HT) with impinging jets of non-Newtonian power law fluid of NF is analyzed under the impacts of MF for a partly curved surface
Nu is attained when compared to Newtonian NF as the power law index becomes higher while the amount of rise in the HT depends upon the Re number
Summary
Even though NFs technology has been used in many impinging jet HT applications and even in some few studies MF effects were considered, non-Newtonian power law fluid effects considering nanoparticles for jet impinging curved target surface including impacts of MF has never been considered in the literature. HT exist in diverse thermal engineering field, the outcomes of the present work will be helpful in the initial design and optimization of convective HT with impinging jet of non-Newtonian power law fluid with MF effects. The results will be presented in terms of flow and thermal patterns visualizations, Nu number variations considering various values of Re number, MF strength and inclination, power law index of non-Newtonian fluid, solid volume fraction/size of the particles and curvature ratio of the impinging wall. In the second part of the modeling, convective HT performance estimation by using adaptive neuro-fuzzy interface system (ANFIS) will be performed for various input parameters
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