Influence of hybrid nano-structures on thermal performance of shear rate dependent viscosity fluid over a heated rotatin
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Influence of hybrid nano‑structures on thermal performance of shear rate dependent viscosity fluid over a heated rotating cone with Hall and ion slip currents M. Nawaz1 · S. Batool1 · Yasser Elmasry2 Received: 26 March 2020 / Accepted: 14 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The fluid of shear rate dependent viscosity has totally different rheology and exhibits dynamics which play a key role in heat transfer rate and friction experienced by surface over which this type of fluid is considered in this study as this type of fluids are extensively used in thermal processes. The governing laws and constitutive equations for hyperbolic tangent fluid and thermo-physical relation correlation for hybridity of nano-structures are simultaneously solved via finite element method (FEM). The predictions are recorded, and outcomes are explained. It is found from outcomes that suspension of hybrid nanostructures is the most approximate technique for the enhancement of thermal performance of coolant (hyperbolic tangent fluid). The process of diffusion of wall momentum into fluid speeds down as viscosity decreases as a function of shear rate. It is predicted from simulations that mono nanofluid is less shear thinning than hybrid nanofluid. Hence, if it is desired to reduce shear thinning phenomenon, enhance the thermal performance and suspension of hybrid nano-structures are recommended. The results are validated by comparing them with already published benchmarks. The parameters are varied, and simulations are recorded in term of numerical values and graphical data. The rotation of micro-structures has shown significant reduction in angular velocity of mono and hybrid nanofluids. Angular field has depicted an increasing trend when vortex viscosity parameter is varied through increasing values. Temperature decreases as a result of an increase in thermal relaxation time. Hence, thermal memory effects play a significant role in controlling the thermal boundary layer thickness. Keywords Shear rate dependent viscosity · Heat flux · Suspension of hybrid structures · Thermal performance · Hall and ion slip currents List of symbols x, z Space coordinates (m) g1 Gravitational force (N) T Temperature field (K) Uw Wall velocity (ms−1) Tw , T∞ Wall and ambient temperature (K) Cf , Cg Skin friction coefficients B0 Magnetic field (A kg−2) k Thermal conductivity (Wm−1) hs Heat source parameter L Characteristic length (m) * M. Nawaz [email protected] 1
Department of Applied Mathematics and Statistics, Institute of Space Technology, P.O. Box 2750, Islamabad 44000, Pakistan
Department of Mathematics, College of Sciences, King Khalid University, Abha 61413, Saudi Arabia
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u, v, w Velocity components (ms−1) f, g Velocity components (𝜌c)p Specific heat capacity (J kg−1 K) M 2 Magnetic field parameter Pr Prandtl number Ff Porous medium coefficient (N) Qh Heat sink coefficient FD Inertia coefficient We Weissenberg number Qw Heat flux (Wm−2) Subscripts f Base fluid nf Nanofluid Ec Eckert
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