Numerical study of magnetic field effect on the ferrofluid forced convection and entropy generation in a curved pipe

This paper presents the effect of a magnetic field on the ferrofluid flow pattern, heat transfer and entropy generation in a curved pipe. A non-uniform magnetic field is applied to ferrofluid (water+2% vol. Fe3O4 nanoparticles) flow and under the constant heat flux boundary condition. Governing equations are solved by the finite volume method and based on the SIMPLE algorithm. The major objective of this work is to illustrate the effects of circumferential angle mml:mfenced close=) open=(separators=0 degrees <=phi <= 180 degrees mml:mfenced> and strengths of a magnetic field mml:mfenced close=) open=( separators=0 <= Mn <= 3x106mml:mfenced> on the hydro-thermal behavior and entropy production rate. It is found that circumferential angle of the magnetic source plays an important role in hydro-thermal performance of a curved pipe. At low magnetic numbers, the optimal circumferential location of the magnetic source is phi opt=180 degrees which leads to the maximum heat transfer enhancement and hydro-thermal performance and the minimal entropy generation rate. For high magnetic numbers, the optimal operating condition occurs at phi=0 degrees and phi=60 degrees depending on the magnetic number. Second law analysis reveals that the major source of entropy generation comes from heat transfer irreversibility which reduces significantly by applying a magnetic field. In the range of studied parameters, the maximum heat transfer enhancement is about 29% which occurs at phi=0 degrees and Mn=3x106.