Experimental and Numerical Investigations of Magnetohydrodynamics of Magnetic Fluid

Abstract: In this investigation, the magnetohydrodynamics of magnetic fluid (MF) is experimentally and numerically studied. The free surface of gas bubble is tracked using the PLIC (Piecewise Linear Integration Calculation)-VOF (Volume of Fluid) method and surface tension is solved by CSF (Continuous Surface Force) method.1. The gas bubble rising in the magnetic fluid is studied. The effects of Mo and E(o|¨) number on the motion and deformation of gas bubble are considered. It is found that the motion and deformation of bubble is restrained as the Mo number increases and the breakage of bubble at the edges is observed as the E(o|¨) number increases.2. Gas bubble rising in a pressurized fluid column is studied. The motion and deformation of gas bubble are predicted. The effects of wall and pressure are considered and the computed results indicate that when the wall effect was considered, as the pressure increases, the bubble shape deforms from spherical cap to bullet-like shape, the shape aspect ratio decreases and the velocity of the bubble is significantly reduced, the shape aspect ratio increases when the wall effect is not considered.3. The gas bubble rising in a magnetic fluid is studied. The motion and deformation of gas bubble are predicted. The effect of intensity of magnetic field on the rising bubble with various initial shapes is studied. It is found that the terminal bubble shape depends on the intensity of magnetic field. In the case of a weak magnetic field, dynamic pressure is dominant and makes the bubble oblate and the initial bubble shape slightly influences the final state of bubble when there is no magnetic field, while in the case of a strong magnetic filed, the magnetic pressure is equal to dynamic pressure, which makes the bubble spherical.4. The behavior of two bubbles is numerically studied. The effects of fluid regime and magnetic field are considered. It is found both of them are essential to bubble motion and deformation.5. Numerical and experimental analysis of gas bubble emitting downwards into water and magnetic fluid is performed. The bubble formation and burst regimes are reappeared by numerical modeling and simulation using the PLIC-VOF method. The sharps of gas bubble and the period of the growing process are obtained by numerical simulation. The experimental measurements are conducted using a CCD camera. Quantitative agreement has been achieved between the experimental and simulated results.6. The behavior of magnetic fluid flowing through an abrupt expansion is investigated with/without the application of magnetic field. The influence of magnetic field is conducted by changing the magnetic force, and the results are compared with non-magnetic form…
Key words: Magnetic fluid; bubble; PLIC-VOF method; CSF method

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