فهرست مقالات Blocked-Off

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  1 - Geometrical Effects of Duct on the Entropy Generation in the Laminar Forced Convection Separated Flow
  Nasrin Aminzadeh Shima Sotoodehnia Meysam Atashafrooz
  In this research paper, irreversibility analysis of laminar forced convection flow in a duct with variable cross-section are numerically studied. Two-dimensional Cartesian coordinate system is used to solve the set of governing equations and also the blocked-off method چکیده کامل

  In this research paper, irreversibility analysis of laminar forced convection flow in a duct with variable cross-section are numerically studied. Two-dimensional Cartesian coordinate system is used to solve the set of governing equations and also the blocked-off method is considered for simulation of the inclined surfaces. To obtain the velocity and temperature fields, the basic equations are numerically solved using the finite volume method and SIMPLE algorithm. To determine the flow irreversibility, the entropy generation number is calculated according to the thermodynamic second law. The geometrical effects of duct on the distributions of streamlines, friction coefficient, Nusselt number, entropy generation, and Bejan number are presented with details. The results show that the duct heights and inclination angle of surfaces have great effects on the flow irreversibility and the hydrodynamics and thermal behaviours. Also, comparison of the present numerical results with the available data published in the open literature shows an excellent consistency. پرونده مقاله
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  2 - Numerical Study of Non-Gray Radiative Heat Transfer in a T-shaped Furnace
  Amin Al Taha MohamadMehdi Keshtkar
  Radiative heat transfer has an important role in many industrial equipment; i.e. furnaces, boilers and high temperature heat exchangers. In this paper, combination of Weighted Sum of Gray Gas Method (WSSGM) and Discrete Ordinate Method (DOM) are used together in order t چکیده کامل

  Radiative heat transfer has an important role in many industrial equipment; i.e. furnaces, boilers and high temperature heat exchangers. In this paper, combination of Weighted Sum of Gray Gas Method (WSSGM) and Discrete Ordinate Method (DOM) are used together in order to numerically study the radiative heat transfer behavior in a non-gray participating medium. Moreover, the concept of Blocked-off region for irregular geometries is used to simulate the T-shaped furnace. The effect of different radiative parameters, i.e. scattering coefficient and wall emissivity on thermal behavior and wall heat fluxes is investigated and compared for both gray and non-gray media. The results show thatwhen scattering coefficient increases, more radiation is scattered in the medium and therefore less heat flux reaches the walls such that by increasing scattering coefficient from 1.0 to 5.0, the incident radiative heat flux decreases up to 15% in some parts of bottom wall. It is seen that by increasing wall emissivity from 0.5 to 1.0, wall heat flux increases more than 60%. Moreover, results show that, by increasing the temperature, the maximum error strongly increases which indicates that in many engineering problems, the gray medium assumption leads to great error in results. پرونده مقاله
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  3 - Application of Improved Blocked-Off Method to Simulate the Interacting Influences of Obstacle Shape and Wall Velocity on the Turbulent Mixed Convection Flow in a Trapezoidal Cavity
  Meysam Atashafrooz
  10.30486/admt.2022.1952976.1341
  In the current research, interaction influences of obstacle shape and top wall velocity on the hydrothermal behaviours of the turbulent mixed convection flow in a trapezoidal cavity are numerically simulated. To achieve this goal, three different shapes of the obstacles چکیده کامل

  In the current research, interaction influences of obstacle shape and top wall velocity on the hydrothermal behaviours of the turbulent mixed convection flow in a trapezoidal cavity are numerically simulated. To achieve this goal, three different shapes of the obstacles including semicircular, triangular, rectangular are considered. Dimensions of these obstacles are chosen so that the environment around all three of them is same. The RNG model is chosen to simulate the turbulent flow. To model the inclined or curved walls of trapezoidal cavity and obstacles, the improved blocked-off method is applied. Results show that the obstacle shape and top wall velocity have a significant influence on the thermal and hydrodynamic behaviours. In fact, the highest magnitude of heat transfer rate along the bottom wall occurs in the cavity with the rectangular obstacle and for the highest magnitude of top wall velocity; whilst its lowest magnitude is related to the pure free convection and for the cavity with the semicircular obstacle. Besides, the lowest and highest magnitudes of temperatures fields occur for the cavities with rectangular and triangular obstacles, respectively. پرونده مقاله