Browsing by Author "Öztop, HE"

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    Natural convection in a flexible sided triangular cavity with internal heat generation under the effect of inclined magnetic field
    Selimefendigil, F; Öztop, HE
    In this numerical study, magnetohydrodynamics natural convection in a flexible sided triangular cavity with internal heat generation is investigated. The inclined wall of the cavity is cooled and flexible while the left vertical wall is partially heated. Galerkin weighted residual finite element method is used to solve the governing equations. The effects of pertinent parameters such as external Rayleigh number (between 10(4) and 10(6)), internal Rayleigh number (between 10(4) and 10(7)), elastic modulus of flexible wall (between 500 and 10(5)), Hartmann number (between 0 and 40) and inclination angle of the magnetic field (between 0 degrees and 90 degrees) on the fluid flow and heat transfer characteristics were numerically investigated. It was observed local and averaged Nusselt number enhance with external Rayleigh number but in the vicinity of the upper location of the heater local heat transfer deteriorates due to the inclined wall deformation with increasing external Rayleigh number. Heat transfer reduces with internal Rayleigh number and Hartmann number. Averaged heat transfer decreases 13.25% when internal Rayleigh number is increased from 10(4) to 10(7) and decreases 40.56% when Hartmann number is increased from 0 to 10. The reduction in the convection with magnetic field is effective for higher values of external Rayleigh numbers and averaged heat transfer increases with magnetic field inclination angle. (C) 2016 Elsevier B.V. All rights reserved.
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    Thermal Management and Modeling of Forced Convection and Entropy Generation in a Vented Cavity by Simultaneous Use of a Curved Porous Layer and Magnetic Field
    Selimefendigil, F; Öztop, HE
    The effects of using a partly curved porous layer on the thermal management and entropy generation features are studied in a ventilated cavity filled with hybrid nanofluid under the effects of inclined magnetic field by using finite volume method. This study is performed for the range of pertinent parameters of Reynolds number (100 <= Re <= 1000), magnetic field strength (0 <= Ha <= 80), permeability of porous region (10(-4) <= Da <= 5 <= 10 2), porous layer height (0.15 H <= tp <= 0.45H), porous layer position (0.25 H <= yp <= 0.45 H), and curvature size (0 <= b <= 0.3 H). The magnetic field reduces the vortex size, while the average Nusselt number of hot walls increases for Ha number above 20 and highest enhancement is 47% for left vertical wall. The variation in the average Nu with permeability of the layer is about 12.5% and 21% for left and right vertical walls, respectively, while these amounts are 12.5% and 32.5% when the location of the porous layer changes. The entropy generation increases with Hartmann number above 20, while there is 22% increase in the entropy generation for the case at the highest magnetic field. The porous layer height reduced the entropy generation for domain above it and it give the highest contribution to the overall entropy generation. When location of the curved porous layer is varied, the highest variation of entropy generation is attained for the domain below it while the lowest value is obtained at y(p) - 0.3 H. When the size of elliptic curvature is varied, the overall entropy generation decreases from b = 0 to b = 0.2 H by about 10% and then increases by 5% from b = 0.2 H to b = 0.3 H.