On the performance of heat absorption/generation and thermal stratification in mixed convective flow of an Oldroyd-B fluid

Ramping Wall Boundary Analysis of Buoyant-Driven Convection Magnetohydrodynamics (MHD) Flow of B–H2O and Al2O3–H2O Nanofluid Past Vertical Edge in a Porous Zone

An analysis is explored to study ramping wall velocity, temperature and concentration as well as isothermal case of a nanofluid flow, suspended boron and aluminium oxide nanoparticles in the seawater at 20°celcius influenced by magnetic and gravitational forces in a semi-infinite flow region using integral transform method. Thermal radiation and heat injection/suction are also investigated. Rosseland’s approximation is used for radiative heat flow in the energy equation, whereas Bousinessq’s approach is used in the momentum equation. Fluid temperature, species concentration, and transport are solved using Heaviside, exponential and complementary error functions; friction drag, heat and mass transfer rates are solved using Gaussian error functions. Temperature, transport and species concentration are graphically exhibited while the numerical calculations have been carried out for friction drag, rate of heat transmission and Sherwood number are performed for both the ramped wall and isothermal cases, and the effects of emerging parameters are tabulated and discussed. Higher radiation parameters lead to an increase in fluid temperature. The velocity boundary layer is lowered by the magnetic field and porous media parameters. The Nusselt number drops as Prandtl number, radiation parameter and volume fraction grows for both ramping and isothermal situations, whereas increases when time and heat source parameter increases.

Radiative MHD unsteady Casson fluid flow with heat source/sink through a vertical channel suspended in porous medium subject to generalized boundary conditions

Unsteady, incompressible flow of Casson fluid between two infinitely long upward heated walls nested in a porous medium is analyzed in this work. The mass diffusion and heat transfer phenomena are also studied in the presence of thermal radiation, magnetic field, and heat source/sink. The generalized boundary conditions in terms of continuous time-dependent functions are considered for mass, energy, and momentum fields. Fick’s law, Fourier’s law, and momentum conservation principle are adopted to formulate the mathematical equations. Analytic solution for the concentration equation is established first by adding certain unit-less quantities and then by using the Laplace method of transformation. Semi-analytic solutions are calculated by means of Stehfest’s numerical Laplace inversion algorithm for energy and velocity equations. To demonstrate the verification of those solutions, a tabular comparison is drawn. Graphical illustrations along with physical descriptions are provided to discuss the essential contribution of thermo-physical parameters in heat and mass transfer and flow of the Casson fluid. The numerical computations of Sherwood number, Nusselt number, and skin friction for various inputs of related parameters are organized in tables to investigate mass transfer rate, heat transfer rate, and shear stress respectively. It is observed that porosity of the medium and buoyancy force tend to accelerate the flow. The heat and mass transfer rates are appreciated by Prandtl and Schmidt numbers respectively. Furthermore, radiation parameter and Grashof number significantly minimize the shear stress.

Analytical evaluation of Oldroyd-B nanoliquid under thermo-solutal Robin conditions and stratifications

Chilling systems are important in the improved technological thermal mechanisms which are considered continuously in passive along with active heat-transference improvement procedures. Engineers recommended several approaches to upsurge heat transference of thermal structures. The pulsating flow, corrugated tube, magnetic field aspect and nanoliquids are the heat-transference improvement procedures delved continuously. In present research work, we addressed the heat-transference characteristics of non-Newtonian (Oldroyd-B) liquid towards heated stratified surface. Thermally radiative laminar flow is modeled. In addition, we accounted Buongiorno's nanoliquid model which includes Brownian along with thermophoretic diffusions. Modeling is further based on heat source, magnetohydrodynamics, dual stratification, thermal radiation and convective conditions. Mathematical system is simplified through boundary-layer idea. Similarity variables are reported with the aim to simplify complex mathematical system. Homotopy algorithm yields convergent results of non-dimensional expressions. Our study unveils diminution of thermal along with solutal fields when stratification factors are increased.

Entropy optimized dissipative CNTs based flow with probable error and statistical declaration

BACKGROUND

CNTs are categorized subject to their structures i.e., SWCNTs (single wall nanotubes), DWCNTs (double wall nanotubes) and MWCNTs (multi-wall nanotubes). The various structures have distinct characteristics that make the nanotubes suitable for various physical applications. It is due their unique electrical, mechanical and thermal attributes CNTs present thrilling opportunities for mechanical engineering, industrial, scientific research and commercial applications. There is fruitful potential for carbon nanotubes in the composites business and industry. Today, CNTs find utilization in frequent various products, and analyst continue to explore new applications. Currently applications comprise wind turbines, bicycle components, scanning probe microscopes, flat panel displays, marine paints, sensing devices, electronics, batteries with longer lifetime and electrical circuitry etc. Such applications in mind, entropy optimized dissipative CNTs based flow of nanomaterial by a stretched surface. Flow is caused due to stretching phenomenon and studied in 3D coordinates. Both types of CNTs are studied i.e., SWCNTs and MWCNTs. CNTs are considered for nanoparticles and water for continuous phase fluid. Special consideration is given to the analysis of statistical declaration and probable error for skin friction and Nusselt number. Furthermore, entropy rate is calculated. Entropy rate is discussed in the presence of four main irreversibilities i.e., heat transfer, Joule heating, porosity and dissipation.

METHOD

Homotopy technique is utilized to develop the convergence series solutions.

RESULTS

Impacts of sundry variables subject to both SWCNTs (single) and MWCNTs (multi) are graphically discussed. Statistical analysis and probable error for surface drag force and Nusselt number are numerically calculated subject to various flow variables. Numerical results for such engineering quantities are displayed through tables. In addition, comparative analysis for SWCNTs and MWCNTs are presented for the velocity, concentration and thermal fields.

CONCLUSIONS

Results for entropy rate is calculated in the presence of various sundry variable through implementation of second law of thermodynamics. It is examined from the results that velocity decreases for both CNTs via higher magnetic, inertia coefficient and porosity parameters. Secondary velocity i.e., velocity in g-direction boosts up versus rotation parameter while it declines for larger slip parameter for both CNTs. thermal field intensifies for both CNTs via larger heat generation/absorption parameter. Concentration which shows the mass transfer of species increases subject to higher homogeneous parameter and Schmidt number in case of both CNTs. Entropy rate in more for larger magnetic, Reynolds number and slip parameter. Bejan number boosts up for higher Reynold number and slip parameter while it declines for magnetic parameter.

Unsteady Radiative Natural Convective MHD Nanofluid Flow Past a Porous Moving Vertical Plate with Heat Source/Sink

In this research article, we investigated a comprehensive analysis of time-dependent free convection electrically and thermally conducted water-based nanofluid flow containing Copper and Titanium oxide (Cu and TiO 2 ) past a moving porous vertical plate. A uniform transverse magnetic field is imposed perpendicular to the flow direction. Thermal radiation and heat sink terms are included in the energy equation. The governing equations of this flow consist of partial differential equations along with some initial and boundary conditions. The solution method of these flow interpreting equations comprised of two parts. Firstly, principal equations of flow are symmetrically transformed to a set of nonlinear coupled dimensionless partial differential equations using convenient dimensionless parameters. Secondly, the Laplace transformation technique is applied to those non-dimensional equations to get the close form exact solutions. The control of momentum and heat profile with respect to different associated parameters is analyzed thoroughly with the help of graphs. Fluid accelerates with increasing Grashof number (Gr) and porosity parameter (K), while increasing values of heat sink parameter (Q) and Prandtl number (Pr) drop the thermal profile. Moreover, velocity and thermal profile comparison for Cu and TiO 2 -based nanofluids is graphed.