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Evanescent magnetic field effects on entropy generation at the onset of natural convection

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Abstract

This paper numerically investigates the effect of an externally evanescent magnetic field on total entropy generation in a fluid enclosed in a square cavity by using a control volume finite element method to solve the conservation equations at Prandtl number of 0·71. The values of relaxation time of the magnetic field are chosen, so that the Lorentz force acts only in the transient state of entropy generation in natural convection. The total entropy generation was calculated for, fixed value of irreversibility distribution ratio, different relaxation time varying from 0 to 1/5 and Grashof number varying from 104 to 105. The effects of the Hartman number and the magnetic field inclination angle on the evolution of total entropy generation throughout the transient regime were investigated. Results show that the application of evanescent magnetic field not only suppresses the fluctuation of the total entropy generation in the transient state, but also reduces the gap for magnetic field relaxation time less than 1/10.

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Authors and Affiliations

  1. High Institute of Applied Sciences and Technology of Gabes, Omar Ibn El Khattab Street, Gabes, 6029, Tunisia

    Mourad Magherbi

  2. National School of Engineers of Gabes, Omar Ibn El Khattab Street, 6029, Gabes, Tunisia

    Atef El Jery, Nejib Hidouri & Ammar Ben Brahim

Authors
  1. Mourad Magherbi
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  2. Atef El Jery
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  3. Nejib Hidouri
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  4. Ammar Ben Brahim
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Correspondence to Mourad Magherbi.

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Magherbi, M., El Jery, A., Hidouri, N. et al. Evanescent magnetic field effects on entropy generation at the onset of natural convection. Sadhana 35, 163–176 (2010). https://doi.org/10.1007/s12046-010-0021-1

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  • DOI: https://doi.org/10.1007/s12046-010-0021-1

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