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Showing 3 results for Joule Heating
Mohammad Mahdi Afsari, Seyed Ali Mirbozorgi,
Volume 12, Issue 6 (3-2013)
Abstract
Flow analysis in the microchannels has recently accelerated dramatically. In this paper, numerical investigation of Joule heating effects on the electroosmotic flow through a microchannel with the trapezoidal cross-section and constant wall temperature have been presented. The energy equation for the temperature distribution, Navier–Stokes equation for the velocity distribution and a Poisson equation for the electric potential distribution have been solved by using the finite-volume method in a system curvilinear coordinates. Thermophysical properties such as the dynamic viscosity and electric conductivity vary with temperature. Results show that by increasing the Joule number, the temperature, velocity and mass flow rate increase with constant EDL number. Without considering the Joule heating effects, the increments of EDL number causes in the mass flow rate to increase, but with considering the joule heating effects, the increasing of mass flow rate continues until EDL number 15 and after that the flow rate decreases. On the other hand, when the cross-section is reduced by the increasing aspect ratio, the joule number remains constant while the mean temperature decreases.
Mohammad Pourjafargholi, Ghanbarali Sheikhzadeh, Reza Maddahian,
Volume 17, Issue 8 (10-2017)
Abstract
In the present work, numerical simulation of steady, compressible and supersonic airflow in a magneto-hydrodynamic (MHD) generator has been studied. This flow considered to be ideal with low magnetic Reynolds number. A two-dimensional channel with four-pair electrodes and with various geometries and boundary conditions were utilized as a MHD Faraday generator model. The computational model consists of the Navier-Stokes equations coupled with electromagnetic source terms, Maxwell's equations and Ohm's law. Implicit based on density solver is used to solve the Navier-Stokes and the electric potential method is used to solve the Poisson's equation. First, the boundary conditions of constant temperature and constant heat flux were compared. Due to the less Joule heating and generation of higher electrical power, constant heat flux boundary condition was selected to continue working.
F. Karami, M. Sabzpooshani,
Volume 19, Issue 3 (3-2019)
Abstract
The aim of this research is an analytical investigation of heat and mass transfer for the MHD nanofluid flow passed between non-parallel stretchable/shrinkable walls. In order to model nanofluid flow, effects of Thermophoresis, Brownian diffusion, and Joule heating are considered. The governing mass, momentum, and energy equations are solved analytically by applying Duan-Rach method, which caused to get a solution for the undetermined coefficients from conjectured profiles of variables without using numerical methods. Comparison between the current results with the numerical results of other references shows good agreement. The effects of the Reynolds number, opening angle parameter, and the Hartman number on the temperature, velocity, and concentration profiles have been investigated in the case of both convergent and divergent plates, either stretched or shrunk. Also, the effects of the Thermophoretic and Brownian parameters on the Nusselt number are obtained. This study indicates that increasing the Hartman number decreases the concentration profile and increasing in the temperature profile for divergent channels. In this case, as the opening angle parameter rises, the thickness of the thermal boundary layer increases. Also, for convergent and divergent channels, the increase in the thermophoretic parameter causes increases the Nusselt number. By applying an identical magnetic field to two divergent stretching and shrinking channels, the concentration profile in the stretching channel is more than the shrinking one. For convergent channels, this treatment of concentration profile is completely vice versa.
