Magnetohydrodynamic double-diffusive natural convection for nanofluid within a trapezoidal enclosure

2019

Heliyon

Self Cite

A numerical investigation of entropy generation, heat and mass transfer is performed on steady double diffusive natural convection of water-based Al2O3 nanofluid within a wavy-walled cavity with a center heater under the influence of an uniform vertical magnetic field. The top horizontal wavy wall, left and right vertical walls of the enclosure are kept at low temperature and concentration of Tc and cc whereas central part of the bottom horizontal wall is maintained at high temperature and concentration of Th and ch and the remaining part is kept adiabatic where temperature and concentration gradient are taken as zero. The Bi-CGStab method and Tri-diagonal algorithm are used to solve the governing equations. The study has been performed for several relevant parameters such as Rayleigh number (103≤Ra≤105), Hartmann number (0≤Ha≤60), buoyancy ratio number (badbreakafter−2≤N≤2), volume fraction of nanoparticles (0.0≤ϕ≤0.2) and different undulation number of the upper wavy wall (n). The Prandtl number and Lewis number are kept fixed at Prgoodbreakafter=6.2 and Legoodbreakafter=2. The effect of these parameters are revealed in terms of streamlines, isotherms, isoconcentrations, entropy generation, average Nusselt number and Sherwood number. Results indicate that heat and mass transfer rate augment as Rayleigh number and volume fraction of nanoparticles increase and are found to drop with the increase in Hartmann number and buoyancy ratio.

“…Substituting from eq. (19) and writing in (20), we get the following biharmonic equation in stream function-velocity formulation…”

Section: Methodsmentioning

confidence: 99%

“…Rahman et al [19] investigated MHD double-diffusive mixed convection in a horizontal channel with an open cavity. Mahapatra et al [20] presented numerical study of double-diffusive natural convection in a trapezoidal enclosure filled with nanofluid under the influence of magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of MHD double diffusive natural convection and entropy generation in a wavy enclosure filled with nanofluid with discrete heating

Parveen

2019

Heliyon

Self Cite

“…(23) - (25) are:

where the co-efficient matrices

and

are of order mn and the number of components in the vectors ψ , θ , S and f is mn for a grid size m × n. The governing Eqs. (6) - (10) are non-linear and the use of non-uniform grid leads to non-symmetric matrices which motivates us to use biconjugate gradient stabilized method (BiCGStab) (see, [33] ) that constitutes inner iterations. The Eqs.…”

Section: Co-ordinate Transformation and Numerical Proceduresmentioning

confidence: 99%

Entropy generation in nanofluid flow due to double diffusive MHD mixed convection

Mondal

Parveen

2021

Heliyon

Self Cite

Lid driven trapezoidal enclosure Low aspect ratio Double diffusive nanofluid flow This work is concerned with the numerical study of laminar, steady MHD mixed convection flow, and entropy generation analysis of 2 3-water nanofluid flowing in a lid-driven trapezoidal enclosure. The aspect ratio of the cavity is taken very small. The cavity is differentially heated to study the fluid flow, heat, and mass transfer rate. The adiabatic upper wall of the enclosure is allowed to move with a constant velocity along the positive-direction. The second-order finite difference approximation is employed to discretize the governing partial differential equations, and a stream-function velocity formulation is used to solve the coupled non-linear partial differential equations numerically. The simulated results are plotted graphically through streamlines, isotherms, entropy generation, Nusselt number, and Sherwood number. The computations indicate that the average Nusselt number and average Sherwood number are decreasing functions of Hartmann number, aspect ratio, and nanoparticle volume fraction. Significant changes in streamlines, temperature and concentration contours for high Richardson number are observed.

“…( 15)-( 19) are solved numerically using finite-difference approximation http://www.journals.vu.lt/nonlinear-analysis method. Using second-order approximations of different derivatives of stream function, temperature, concentration, heat function and mass function (see [20]), the discretizations of Eqs. ( 15)-( 19) can be written in matrix form as…”

Section: Coordinate Transformation and Numerical Proceduresmentioning

confidence: 99%

Minimization of entropy generation due to MHD double diffusive mixed convection in a lid driven trapezoidal cavity with various aspect ratios

Mondal

2020

NAMC

Entropy generation minimization has significant importance in fluid flow, heat and mass transfer in an enclosure to get the maximum efficiency of a system and to reduce the loss of energy. In the present study, the analysis of mixed convection fluid flow, heat and mass transfer with heat line and mass line concept and entropy generation due to the effects of fluid flow, heat flow, mass flow and magnetic field in a trapezoidal enclosure with linearly heated and diffusive left wall, uniformly heated and diffusive lower wall, cold and nondiffusive right wall, adiabatic and zero diffusion gradient top wall have been reported. Parametric studies for the wide range of Prandtl number (Pr = 0.7 for air cooling system and Pr = 1000 for the engines filled with olive or engine oils), Rayleigh number (Ra = 103–105), aspect ratio (A = 0.5–1.5) and inclination angle of the cavity (ϕ = 45°–90°) have been performed, which help to construct the perfect shape of cavity in many engineering and physical applications so that the entropy is minimum to get the maximum efficiency of any system. The finite-difference approximation has been used to find out the numerical solutions. Biconjugate Gradient Stabilized (BiCGStab) method is used to solve the discretized nonhomogeneous system of linear equations.