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A Cēbers - One of the best experts on this subject based on the ideXlab platform.

  • magnetic field driven micro convection in the hele shaw cell
    Journal of Fluid Mechanics, 2013
    Co-Authors: Kaspars ērglis, Guntars Kitenbergs, A Tatulcenkov, Oksana Petrichenko, F G Ergin, B B Watz, A Cēbers
    Abstract:

    Micro-convection caused by Ponderomotive Forces of the self-magnetic field of a magnetic fluid in the Hele-Shaw cell under the action of a vertical homogeneous magnetic field is studied both experimentally and numerically. It is shown that a non-potential magnetic force at magnetic Rayleigh numbers greater than the critical value causes fingering at the interface between the miscible magnetic and non-magnetic fluids. The threshold value of the magnetic Rayleigh number depends on the smearing of the interface between fluids. Fingering with its subsequent decay due to diffusion of particles significantly increases the mixing at the interface. Velocity and vorticity fields at fingering are determined by particle image velocimetry measurements and qualitatively correspond well to the results of numerical simulations of the micro-convection in the Hele-Shaw cell carried out in the Darcy approximation, which account for Ponderomotive Forces of the self-magnetic field of the magnetic fluid. Gravity plays an important role at the initial stage of the fingering observed in the experiments.

Guntars Kitenbergs - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic field driven micro-convection in the Hele-Shaw cell: the Brinkman model and its comparison with experiment
    Journal of Fluid Mechanics, 2015
    Co-Authors: Guntars Kitenbergs, A Tatulcenkovs, K. Erglis, Petrichenko O, Régine Perzynski, Andrejs Cebers
    Abstract:

    The micro-convection caused by the Ponderomotive Forces of the self-magnetic field in a magnetic fluid is studied here both numerically and experimentally. The theoretical approach based on the general Brinkman model substantially improves the description with respect to the previously proposed Darcy model. The predictions of both models are here compared to finely controlled experiments. The Brinkman model, in contrast to the Darcy model, allows us to describe the formation of mushrooms on the plumes of the micro-convective flow and the width of the fingers. In the Brinkman approach, excellent quantitative agreement is also obtained for the finger velocity dynamics and the velocity maximal values as a function of the magnetic Rayleigh number. The diffusion coefficient of particles of the water-based magnetic colloid determined by the threshold field strength value of the micro-convection is significantly larger than the diffusion coefficient of individual particles. This result is confirmed by independent measurements of the diffusion coefficient at the smearing of the diffusion front.

  • magnetic field driven micro convection in the hele shaw cell
    Journal of Fluid Mechanics, 2013
    Co-Authors: Kaspars ērglis, Guntars Kitenbergs, A Tatulcenkov, Oksana Petrichenko, F G Ergin, B B Watz, A Cēbers
    Abstract:

    Micro-convection caused by Ponderomotive Forces of the self-magnetic field of a magnetic fluid in the Hele-Shaw cell under the action of a vertical homogeneous magnetic field is studied both experimentally and numerically. It is shown that a non-potential magnetic force at magnetic Rayleigh numbers greater than the critical value causes fingering at the interface between the miscible magnetic and non-magnetic fluids. The threshold value of the magnetic Rayleigh number depends on the smearing of the interface between fluids. Fingering with its subsequent decay due to diffusion of particles significantly increases the mixing at the interface. Velocity and vorticity fields at fingering are determined by particle image velocimetry measurements and qualitatively correspond well to the results of numerical simulations of the micro-convection in the Hele-Shaw cell carried out in the Darcy approximation, which account for Ponderomotive Forces of the self-magnetic field of the magnetic fluid. Gravity plays an important role at the initial stage of the fingering observed in the experiments.

Prabal Singh Verma - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear oscillations and waves in multi species cold plasmas
    Physics of Plasmas, 2016
    Co-Authors: Prabal Singh Verma
    Abstract:

    The spatio-temporal evolution of nonlinear oscillations in multi-species plasma is revisited to provide more insight into the physics of phase mixing by constructing two sets of nonlinear solutions up to the second order. The first solution exhibits perfect oscillations in the linear regime and phase mixing appears only nonlinearly in the second order as a response to the Ponderomotive Forces. This response can be both direct and indirect. The indirect contribution of the Ponderomotive Forces appears through self-consistently generated low frequency fields. Furthermore, the direct and indirect contributions of the Ponderomotive Forces on the phase mixing process is explored and it is found that the indirect contribution is negligible in an electron-ion plasma and it disappears in the case of electron-positron plasma, yet represents an equal contribution in the electron-positron-ion plasma. However, the second solution does not exhibit any phase mixing due to the absence of Ponderomotive Forces but results...

  • nonlinear oscillations and waves in multi species cold plasmas
    arXiv: Plasma Physics, 2016
    Co-Authors: Prabal Singh Verma
    Abstract:

    The spatio-temporal evolution of nonlinear oscillations in multi-species plasma is revisited to provide more insight into the physics of phase mixing by constructing two sets of nonlinear solutions up to the second order. The first solution exhibits perfect oscillations in the linear regime and phase mixing appears only nonlinearly in the second order as a response to the Ponderomotive Forces. This response can be both direct and indirect. The indirect contribution of the Ponderomotive Forces appears through self-consistently generated low frequency fields. Furthermore, the direct and indirect contributions of the Ponderomotive Forces on the phase mixing process is explored and it is found that the indirect contribution is negligible in an electron-ion plasma and it disappears in the case of electron-positron plasma, yet represents an equal contribution in the electron-positron-ion plasma. However, the second solution does not exhibit any phase mixing due to the absence of Ponderomotive Forces but results in an undistorted nonlinear traveling wave. These investigations have relevance for laboratory/astrophysical multi-species plasma.

Kaspars ērglis - One of the best experts on this subject based on the ideXlab platform.

  • magnetic field driven micro convection in the hele shaw cell
    Journal of Fluid Mechanics, 2013
    Co-Authors: Kaspars ērglis, Guntars Kitenbergs, A Tatulcenkov, Oksana Petrichenko, F G Ergin, B B Watz, A Cēbers
    Abstract:

    Micro-convection caused by Ponderomotive Forces of the self-magnetic field of a magnetic fluid in the Hele-Shaw cell under the action of a vertical homogeneous magnetic field is studied both experimentally and numerically. It is shown that a non-potential magnetic force at magnetic Rayleigh numbers greater than the critical value causes fingering at the interface between the miscible magnetic and non-magnetic fluids. The threshold value of the magnetic Rayleigh number depends on the smearing of the interface between fluids. Fingering with its subsequent decay due to diffusion of particles significantly increases the mixing at the interface. Velocity and vorticity fields at fingering are determined by particle image velocimetry measurements and qualitatively correspond well to the results of numerical simulations of the micro-convection in the Hele-Shaw cell carried out in the Darcy approximation, which account for Ponderomotive Forces of the self-magnetic field of the magnetic fluid. Gravity plays an important role at the initial stage of the fingering observed in the experiments.

Andrejs Cebers - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic field driven micro-convection in the Hele-Shaw cell: the Brinkman model and its comparison with experiment
    Journal of Fluid Mechanics, 2015
    Co-Authors: Guntars Kitenbergs, A Tatulcenkovs, K. Erglis, Petrichenko O, Régine Perzynski, Andrejs Cebers
    Abstract:

    The micro-convection caused by the Ponderomotive Forces of the self-magnetic field in a magnetic fluid is studied here both numerically and experimentally. The theoretical approach based on the general Brinkman model substantially improves the description with respect to the previously proposed Darcy model. The predictions of both models are here compared to finely controlled experiments. The Brinkman model, in contrast to the Darcy model, allows us to describe the formation of mushrooms on the plumes of the micro-convective flow and the width of the fingers. In the Brinkman approach, excellent quantitative agreement is also obtained for the finger velocity dynamics and the velocity maximal values as a function of the magnetic Rayleigh number. The diffusion coefficient of particles of the water-based magnetic colloid determined by the threshold field strength value of the micro-convection is significantly larger than the diffusion coefficient of individual particles. This result is confirmed by independent measurements of the diffusion coefficient at the smearing of the diffusion front.