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Ahuja, Jyoti
- MHD Effects for a Rotating Nanofluid Layer for LTNE Model
Authors
1 Energy Research Centre, Panjab University, Chandigarh-160014, IN
2 Dr. S.S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh-160014, IN
Source
International Journal of Technology, Vol 6, No 2 (2016), Pagination: 209-214Abstract
Rayleigh-Benard convection of a rotating nanofluid layer under local thermal non-equilibrium model in the presence of magnetic field is investigated. The impact of external applied forces rotation and magnetic field are exhibited by introducing Coriolis force term and Lorentz force term in the momentum equations along with the Maxwell's equations. For considering the impact of local thermal non-equilibrium between the fluid and particle phases; a two-temperature model has been considered. The problem is analysed by making use of the normal mode technique and one term approximation of Galerkin type weighted residual method. Due to thermal non-equilibrium three additional parameters Nield number, modified thermal capacity ratio, modified thermal diffusivity ratio and due to the presence of rotation and magnetic field Taylor number and Chandrasekhar number are introduced. The impact of these parameters on thermal Rayleigh number has been found analytically as well as numerically and presented graphically.
- MHD Stability of a Nanofluid Layer Using Darcy Model:Introduction of Oscillatory Motions for Bottom Heavy Configuration
Authors
1 Energy Research Centre, Panjab University, Chandigarh-160014, IN
2 Dr. S.S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh-160014, IN
3 Department of Mathematics and Statistics, Himachal Pradesh University, Summer Hill, Shimla-171005, IN
Source
International Journal of Technology, Vol 6, No 2 (2016), Pagination: 233-238Abstract
The impact of vertical magnetic field on the thermal instability of a horizontal porous nanofluid layer using Darcy model is considered for free-free boundaries. Brownian motion and thermophoretic forces are introduced due to the presence of nanoparticles and Lorentz's force term is added in the momentum equation along with the Maxwell's equations due to magnetic field. Normal mode technique and single term Galerkin approximation is employed to investigate the instability and derive the eigen value problem. It is found that the mode of instability is through oscillatory motions for bottom heavy suspension of nanoparticles. The reason for the existence of oscillatory motions is due to the occurrence of two opposite buoyancy forces i.e. density variation due to heating and density gradient of nanoparticles at the bottom of the layer. The thermal Rayleigh number increases with the increase of Chandrasekhar number and decreases with the increase of porosity. The effect of Lewis number, modified diffusivity ratio, concentration Rayleigh number and heat capacity ratio on the onset of thermal convection has been investigated analytically and presented graphically.- Hall Effect on Thermal Convection of a Nanofluid Layer Saturating a Porous Medium
Authors
1 University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh-160014, IN
2 Energy Research Centre, Panjab University, Chandigarh-160014, IN
Source
International Journal of Technology, Vol 4, No 1 (2014), Pagination: 1-6Abstract
The present paper investigates the stability analysis of an electrically conducting horizontal layer of nanofluid in the presence of Hall currents saturating a porous medium for bottom heavy distribution of nanoparticles. Hall currents are the effects whereby a conductor carrying an electric current perpendicular to an applied magnetic field develops a voltage gradient which is transverse to both the current and the magnetic field. The nanofluid layer incorporates the effect of Brownian motion and the rmophoresis while Darcy's law is used for the porous medium. The analysis is carried out in the framework of linear stability theory, normal mode technique and Galerkin type weighted residuals method. The present formulation of the problem leads to oscillatory mode of instability whereas for top heavy arrangement of nanoparticles the instability is invariably through stationary convection. The reason for the oscillatory mode of convection is the competition between the density gradient caused by bottom heavy nanoparticle distribution with the density variation caused by heating from the bottom. Further, it is found that the effect of magnetic field is to postpone the onset of instability while that of Hall currents and porosity is to hasten the onset of thermal convection.