Thermosolutal natural convection energy transfer in magnetically influenced casson fluid flow in hexagonal enclosure with fillets

Current disquisition is aimed to adumbrate thermosolutal convective diffusion transport in Casson fluid filled in hexagonal enclosure under effectiveness of inclined magnetic field. Partially iso-concentration and iso-temperature distributions at base wall of enclosure is provided along with incorporation of fillets at corners of flow domain. Governing formulation in 2D are expressed in a velocity-pressure, energy and concentration bal-ance equations. Numerical computations are executed by employing COMSOL Multiphysics software based on finite element scheme. Domain discretization in manifested by performing hybrid meshing in view of 2D ele-ments. Linear and quadric interpolating polynomials for pressure and other associated distributions are capi-talized. Non-linearized discretization system is handled by non-linear solver renowned as PARADISO. Results and code validation is assured by performing comparison and grid convergence test respectively. The impact of flow concerning variables by considering wide ranges like Casson parameter (0.1 <= beta <= 10), Rayleigh number (10(4) <= Ra <= 10(7)), Hartmann number (20 <= Ha <= 80) and Lewis number (0.1 <= Le <= 10) on velocity, isothermal and isoconcentration fields are visualized through graphs and tables. Visualization about kinetic energy along with heat and mass transfer rates are disclosed through graphs and tables.Funding The work of U.F.-G. was supported by the Government of the Basque Country for the ELKARTEK21/10KK-2021/00014 and ELKARTEK22/85 research programs, respectively

Enhancement of the Hydrodynamic Characteristics in Shell-and-Tube Heat Exchangers by Using W-Baffle Vortex Generators

Improving the hydrodynamic characteristics of STHECs (Shell-and-Tube Heat Exchanger Channels) by using BVGs (Baffle-type Vortex Generators) is among the common passive methods due to their proved efficiency. In this computational investigation, the&nbsp;same method is used to enhance the hydrodynamic behavior of STHECs, by inserting W-shaped Baffle-type Vortex Generators. The&nbsp;numerical model represented by the computational FVM (Finite Volume Method) is used to simulate and analyzed the considered physical model. The fluid used is air, its thermal physical properties are constant, turbulent, incompressible, and its temperature is 300&nbsp;K at&nbsp;the inlet section of the STHEC. The flow velocity ( Uin ) and atmospheric pressure ( Patm ) are considered as boundary conditions at&nbsp;the entrance (x&nbsp;= 0) and exit (x = L) of the channel, respectively. The results showed that the friction coefficients were related to&nbsp;the pressure, velocity, and Reynolds number values. High values of Re yielded an acceleration of the fluid, resulting thus in increased pressure on&nbsp;the solid walls and augmented friction values

Computation of thermo-solutal convection with Soret-Dufour cross diffusion in a vertical duct containing carbon/metallic nanofluids

Duct flows constitute an important category of modern thermal engineering. Optimizing efficiency has become a significant objective in the 21st century in, for example, heating ventilation and air-conditioning (HVAC), coolant or heat transfer fluid flows in a nuclear power reactor, heat exchanger design etc, and this has been achieved by either new materials (improved thermal insulation properties) constituting the duct walls, novel geometric designs or improved working fluids. Nanotechnology has infiltrated into duct design in parallel with many other fields of mechanical, medical and energy engineering. Motivated by the excellent potential of nanofluids, a subset of materials engineered at the nanoscale, in the present work, a new mathematical model is developed for natural convection in a rectangular vertical duct containing nanofluid. The left and right walls of the duct are maintained at constant and unequal temperatures, while the front and rear walls of the duct are insulated. Thermo-solutal (double-diffusive) natural convection of aqueous nanofluid containing various metallic nanoparticles (e. g. copper, titanium oxide) or carbon-based nanoparticles (e. g. diamond, silicon oxide) is simulated. The Tiwari-Das nanoscale volume fraction model is used in addition to the Brinkman and Maxwell models for defining the properties of the nanofluid. The partial differential conservation equations for mass, momentum and energy are non-dimensionalized via appropriate transformations and the resulting boundary value problem is solved with a second-order accurate implicit finite difference technique employing Southwell-Over-Relaxation (SOR). Mesh independence tests are conducted. Extensive visualization of the solutions for velocity, temperature, nanoparticle concentration (volume fraction) are presented for five different nanoparticles (silicon oxide, diamond, copper, titanium oxide and silver), thermal Grashof number, nanoparticle species (solutal) Grashof number, volume fraction of nanoparticles (i.e. percentage doping), Dufour number, Soret number, Prandtl number, Schmidt number and duct aspect ratio. It is observed that the heat transfer rate (Nusselt number) at both the walls is maximized for diamond nanoparticles and minimized for silicon oxide nanoparticles. Further the heat transfer rate for clear fluid is lower when compared with nanofluid, confirming that nanoparticles achieve the desired thermal enhancement at the boundaries also. The mass transfer at both walls (Sherwood number) however is not significantly influenced by any particular type of nanoparticle, thermal and concentration Grashof number and is depleted with higher values of Dufour, Prandtl, Soret and Schmidt numbers in addition to aspect ratio. However, Sherwood numbers at both the left and right duct walls are substantially boosted with greater solid volume fraction of nanoparticles

Numerical simulation of lid driven flow in a curved corrugated porous cavity filled with CuO-water in the presence of heat generation/absorption

In this article, numerical simulation is performed for mixed convection lid-driven flow of CuO-water nanofluid enclosed in a curved corrugated. Cylindrical obstacles having three different constraints: (adiabatic, cold, and heated) at its surface are considered. Internal heat generation/absorption and uniform heat is provided at the vertical wall of the cavity. The bottom wall is insulated, and the curve surfaces are maintained with cold temperature. Mathematically equations are developed from physical problems and solved through Galerkin weighted residual method of FEM formulation. The effect of various Reynold number (), Darcy number (), solid volume fraction of nanoparticles (), heat generation/absorption coefficient () and various cylindrical obstacle on velocity, Nusselt number, molecular movements and the flow structure has been studied. Nusselt number increases for high Darcy number due to the convection in lid cavity. For high Reynold number generally Nusselt numbers decrease or remain the same at the wall with an increase of nanoparticles in porous medium. There significant effect of heat sink coefficient on temperature profile and Nusselt number decreases with increasing of Q

Exact solutions on unsteady convective flow of viscous, casson, second grade and maxwell nanofluids

The heat and mass transfer flow of Newtonian and non-Newtonian nanofluids caused by convection has much practical significance, such as in industries, chemicals, cosmetics, pharmaceuticals and engineering. In this thesis, the unsteady convection flows of Newtonian, non-Newtonian and non-Newtonian hybrid nanofluids such as Casson hybrid, second grade and Maxwell nanofluids in a vertical channel or past a vertical plate will be studied. Carbon nanotubes (CNTs), graphene, cobalt, copper and alumina nanoparticles are used for the enhancement of heat transfer rate of fluids in this research work. Nanofluids have a range of applications in automobiles as coolants, microelectronics, microchips in computer, fuel cells and biomedicine. The problem of free and mixed convection flow of nanofluids is studied in a porous as well as non-porous media, with or without magnetohydrodynamics (MHD) influence. Other conditions like oscillating vertical plate, radiation effect and heat generation have been considered. The idea of Caputo time fractional derivative is used in some problems which is a novel topic nowadays. The advantage of fractional derivative is that the range of derivative increases in this case and the derivative of variable are used for a range of numbers. Appropriate non-dimensional variables are used to reduce the dimensional governing equations along with imposed initial and boundary conditions into dimensionless forms. The exact solutions for velocity, temperature and concentration are acquired via Laplace Transform technique and, in some places, regular perturbation technique along with inverse Laplace transform i.e. Zakian technique. The corresponding expressions for skin friction, Nusselt number and Sherwood’s number have been calculated. The outcomes acquired are plotted via computational software MathCAD-15 using the specific thermophysical properties of nanoparticles and base fluids. The graphical outcomes have been discussed to delineate the impact of various embedded parameters such as radiation parameter, Peclet number, Grashof number, fractional parameter and volume fraction of nanoparticles. Throughout the objectives, velocity of the nanofluid is found to be increasing with increasing thermal/solutal Grashof number, radiation parameter while decreasing with volume fraction of nanoparticles. Temperature profile increases with radiation parameter, heat generation and volume fraction. Thermal conductivity and Nusselt number of the nanofluids exhibit significant increment with increasing volume fraction

Workshops Proceedings

The idea behind the Workshops Proceedings document is to collect in an eBook the information of all the Nanouptake Working Group (WG) Workshops before April 2019 where the participants have been presenting their last research work in nanofluids

Unsteady magnetohydrodynamics (MHD) flow of hybrid ferrofluid due to a rotating disk

The flow of fluids over the boundaries of a rotating disc has many practical uses, including boundary-layer control and separation. Therefore, the aim of this study is to discuss the impact of unsteady magnetohydrodynamics (MHD) hybrid ferrofluid flow over a stretching/shrinking rotating disk. The time-dependent mathematical model is transformed into a set of ordinary differential equations (ODE’s) by using similarity variables. The bvp4c method in the MATLAB platform is utilised in order to solve the present model. Since the occurrence of more than one solution is presentable, an analysis of solution stabilities is conducted. Both solutions were surprisingly found to be stable. Meanwhile, the skin friction coefficient, heat transfer rate—in cooperation with velocity—and temperature profile distributions are examined for the progressing parameters. The findings reveal that the unsteadiness parameter causes the boundary layer thickness of the velocity and temperature distribution profile to decrease. A higher value of magnetic and mass flux parameter lowers the skin friction coefficient. In contrast, the addition of the unsteadiness parameter yields a supportive effect on the heat transfer rate. An increment of the magnetic parameter up to 30% reduces the skin friction coefficient by 15.98% and enhances the heat transfer rate approximately up to 1.88%, significantly. In contrast, the heat transfer is rapidly enhanced by improving the mass flux parameter by almost 20%

Unsteady magnetohydrodynamics (mhd) flow of hybrid ferrofluid due to a rotating disk

The flow of fluids over the boundaries of a rotating disc has many practical uses, including boundary-layer control and separation. Therefore, the aim of this study is to discuss the impact of unsteady magnetohydrodynamics (MHD) hybrid ferrofluid flow over a stretching/shrinking rotating disk. The time-dependent mathematical model is transformed into a set of ordinary differential equations (ODE's) by using similarity variables. The bvp4c method in the MATLAB platform is utilised in order to solve the present model. Since the occurrence of more than one solution is presentable, an analysis of solution stabilities is conducted. Both solutions were surprisingly found to be stable. Meanwhile, the skin friction coefficient, heat transfer rate—in cooperation with velocity— and temperature profile distributions are examined for the progressing parameters. The findings reveal that the unsteadiness parameter causes the boundary layer thickness of the velocity and temperature distribution profile to decrease. A higher value of magnetic and mass flux parameter lowers the skin friction coefficient. In contrast, the addition of the unsteadiness parameter yields a supportive effect on the heat transfer rate. An increment of the magnetic parameter up to 30% reduces the skin friction coefficient by 15.98% and enhances the heat transfer rate approximately up to 1.88%, significantly. In contrast, the heat transfer is rapidly enhanced by improving the mass flux parameter by almost 20%

Computational Fluid Dynamics 2020

This book presents a collection of works published in a recent Special Issue (SI) entitled “Computational Fluid Dynamics”. These works address the development and validation of existent numerical solvers for fluid flow problems and their related applications. They present complex nonlinear, non-Newtonian fluid flow problems that are (in some cases) coupled with heat transfer, phase change, nanofluidic, and magnetohydrodynamics (MHD) phenomena. The applications are wide and range from aerodynamic drag and pressure waves to geometrical blade modification on aerodynamics characteristics of high-pressure gas turbines, hydromagnetic flow arising in porous regions, optimal design of isothermal sloshing vessels to evaluation of (hybrid) nanofluid properties, their control using MHD, and their effect on different modes of heat transfer. Recent advances in numerical, theoretical, and experimental methodologies, as well as new physics, new methodological developments, and their limitations are presented within the current book. Among others, in the presented works, special attention is paid to validating and improving the accuracy of the presented methodologies. This book brings together a collection of inter/multidisciplinary works on many engineering applications in a coherent manner