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Sergey V Komarov – One of the best experts on this subject based on the ideXlab platform.

  • characterization of Acoustic Streaming in water and aluminum melt during ultrasonic irradiation
    Ultrasonics Sonochemistry, 2021
    Co-Authors: Takuya Yamamoto, Kazuki Kubo, Sergey V Komarov
    Abstract:

    Abstract It is well known that ultrasonic cavitation causes a steady flow termed Acoustic Streaming. In the present study, the velocity of Acoustic Streaming in water and molten aluminum is measured. The method is based on the measurement of oscillation frequency of Karman vortices around a cylinder immersed into liquid. For the case of Acoustic Streaming in molten metal, such measurements were performed for the first time. Four types of experiments were conducted in the present study: (1) Particle Image Velocimetry (PIV) measurement in a water bath to measure the Acoustic Streaming velocity visually, (2) frequency measurement of Karman vortices generated around a cylinder in water, and (3) in aluminum melt, and (4) cavitation intensity measurements in molten aluminum. Based on the measurement results (1) and (2), the Strouhal number for Acoustic Streaming was determined. Then, using the same Strouhal number and measuring oscillation frequency of Karman vortices in aluminum melt, the Acoustic Streaming velocity was measured. The velocity of Acoustic Streaming was found to be independent of amplitude of sonotrode tip oscillation both in water and aluminum melt. This can be explained by the effect of Acoustic shielding and liquid density.

  • Investigation on Acoustic Streaming during ultrasonic irradiation in aluminum melts
    Light Metals 2019, 2019
    Co-Authors: Takuya Yamamoto, Sergey V Komarov
    Abstract:

    Acoustic Streaming is a key factor in ultrasonic casting of aluminum alloys because it determines heat and mass transfer, and thus affects the temperature distribution, solidification phenomena, solute transport and crystal growth. However, measurement and prediction of Acoustic Streaming in molten aluminum present a big challenge due to high temperatures and Acoustic Streaming complexity. In this work, a numerical model has been developed to simulate Acoustic Streaming in molten aluminum. The model allows predicting generation of cavitation bubbles, sound wave propagation and attenuation due to interaction with the bubbles, and fluid flow. The model validation has been performed by comparing the predicted and measured Acoustic Streaming in water. Good agreement between these results suggests that the model can be used to predict Acoustic Streaming in actual casting processes. However, a number of issues still remain to be solved particularly an accurate simulation of bubble oscillations.

  • cavitation and Acoustic Streaming generated by different sonotrode tips
    Ultrasonics Sonochemistry, 2018
    Co-Authors: Yu Fang, Takuya Yamamoto, Sergey V Komarov
    Abstract:

    Abstract Aiming at improving the efficiency of cavitation treatment, this work investigates characteristics of Acoustic Streaming and cavitation generated in water by dumbbell-shaped sonotrodes with plane, truncated and conical tips. The main emphasis was placed on elucidating the effects of tip shape and vibration amplitude ranged from 40 to 60  μ m . The PIV technique and Weissler reaction were used to measure flow pattern and velocity of Acoustic Streaming, and cavitation efficiency, respectively. To provide a theoretical explanation to the experimental results, a self-developed mathematical model was used to simulate the Acoustic Streaming and predict the size of cavitation zone numerically. Both the experimental and numerical results revealed that the sonotrode tip shape affects the Acoustic Streaming significantly, altering the flow magnitude and direction from fast and downward under the plane and truncated tips to relatively slow and upward near the conical tip. Besides, the conical tip provides a more efficient cavitation treatment in comparison with the plane and truncated tips. The simulation results showed that widening of cavitation zone and altering of Acoustic Streaming velocity and direction near the sonotrode tip are responsible for the enhancement of cavitation treatment efficiency.

Philippe Marmottant – One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Streaming generated by two orthogonal standing waves propagating between two rigid walls
    Journal of the Acoustical Society of America, 2018
    Co-Authors: Alexander Doinikov, Pierre Thibault, Philippe Marmottant
    Abstract:

    A mathematical model is derived for Acoustic Streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic Streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of Acoustic Streaming. The obtained solutions are used in numerical simulations to reveal the structure of the Acoustic Streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of Acoustic Streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles.

  • Acoustic Streaming induced by two orthogonal ultrasound standing waves in a microfluidic channel
    Ultrasonics, 2018
    Co-Authors: Alexander Doinikov, Pierre Thibault, Philippe Marmottant
    Abstract:

    A mathematical model is derived for Acoustic Streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic Streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of Acoustic Streaming. The obtained solutions are used in numerical simulations to reveal the structure of the Acoustic Streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of Acoustic Streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles.

Jean-paul Garandet – One of the best experts on this subject based on the ideXlab platform.

  • Oscillating Acoustic Streaming jet
    Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2015
    Co-Authors: Brahim Moudjed, Valéry Botton, Jean-paul Garandet, Daniel Henry, Séverine Millet, Hamda Ben Hadid
    Abstract:

    The present paper focuses on the experimental investigation of an oscillating Acoustic Streaming jet. The observations are performed in the far field of a 2MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Two Acoustically absorbing walls are used to delimit the far field zone and avoid Acoustic reflection. Measurements are made by PIV in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high ReynReynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity.

  • Acoustic Streaming jets: A scaling and dimensional analysis
    , 2015
    Co-Authors: Valéry Botton, Brahim Moudjed, Daniel Henry, Séverine Millet, H. Benhadid, Jean-paul Garandet
    Abstract:

    We present our work on Acoustic Streaming free jets driven by ultrasonic beams in liquids. These jets are steady flows generated far from walls by progressive Acoustic waves. As can be seen on figure 1, our set-up, denominated AStrID for Acoustic Streaming Investigation Device, is made of a water tank in which a 29 mm plane source emits continuous ultrasonic waves at typically 2 MHz. Our approach combines an experimental characterization of both the Acoustic pressure field (hydrophone) and the obtained Acoustic Streaming velocity field (PIV visualization) on one hand, with CFD using an incompressible Navier-Stokes solver on the other hand.

  • scaling and dimensional analysis of Acoustic Streaming jets
    Physics of Fluids, 2014
    Co-Authors: Brahim Moudjed, Valéry Botton, Daniel Henry, Ben H Hadid, Jean-paul Garandet
    Abstract:

    This paper focuses on Acoustic Streaming free jets. This is to say that progressive Acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an Acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of Acoustic Streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the Acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in Acoustic Streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical Acoustic experiment. We find that a full similarity is usually not possible between two Acoustic Streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an Acoustic Streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small Acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

James J. Choi – One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Streaming in a Soft Tissue Microenvironment.
    Ultrasound in medicine & biology, 2018
    Co-Authors: Ahmed El Ghamrawy, Florentina De Comtes, Hasan Koruk, Ali Mohammed, Julian R. Jones, James J. Choi
    Abstract:

    We demonstrated that sound can push fluid through a tissue-mimicking material. Although Acoustic Streaming in tissue has been proposed as a mechanism for biomedical ultrasound applications, such as neuromodulation and enhanced drug penetration, Streaming in tissue or Acoustic phantoms has not been directly observed. We developed a material that mimics the porous structure of tissue and used a dye and a video camera to track fluid movement. When applied above an Acoustic intensity threshold, a continuous focused ultrasound beam (spatial peak time average intensity: 238 W/cm2, centre frequency: 5 MHz) was found to push the dye axially, that is, in the direction of wave propagation and in the radial direction. Dye clearance increased with ultrasound intensity and was modelled using an adapted version of Eckart’s Acoustic Streaming velocity equation. No microstructural changes were observed in the sonicated region when assessed using scanning electron microscopy. Our study indicates that Acoustic Streaming can occur in soft porous materials and provides a mechanistic basis for future use of Streaming for therapeutic or diagnostic purposes.

Brahim Moudjed – One of the best experts on this subject based on the ideXlab platform.

  • Oscillating Acoustic Streaming jet
    Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2015
    Co-Authors: Brahim Moudjed, Valéry Botton, Jean-paul Garandet, Daniel Henry, Séverine Millet, Hamda Ben Hadid
    Abstract:

    The present paper focuses on the experimental investigation of an oscillating Acoustic Streaming jet. The observations are performed in the far field of a 2MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Two Acoustically absorbing walls are used to delimit the far field zone and avoid Acoustic reflection. Measurements are made by PIV in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity.

  • Acoustic Streaming jets: A scaling and dimensional analysis
    , 2015
    Co-Authors: Valéry Botton, Brahim Moudjed, Daniel Henry, Séverine Millet, H. Benhadid, Jean-paul Garandet
    Abstract:

    We present our work on Acoustic Streaming free jets driven by ultrasonic beams in liquids. These jets are steady flows generated far from walls by progressive Acoustic waves. As can be seen on figure 1, our set-up, denominated AStrID for Acoustic Streaming Investigation Device, is made of a water tank in which a 29 mm plane source emits continuous ultrasonic waves at typically 2 MHz. Our approach combines an experimental characterization of both the Acoustic pressure field (hydrophone) and the obtained Acoustic Streaming velocity field (PIV visualization) on one hand, with CFD using an incompressible Navier-Stokes solver on the other hand.

  • scaling and dimensional analysis of Acoustic Streaming jets
    Physics of Fluids, 2014
    Co-Authors: Brahim Moudjed, Valéry Botton, Daniel Henry, Ben H Hadid, Jean-paul Garandet
    Abstract:

    This paper focuses on Acoustic Streaming free jets. This is to say that progressive Acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an Acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of Acoustic Streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the Acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in Acoustic Streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical Acoustic experiment. We find that a full similarity is usually not possible between two Acoustic Streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an Acoustic Streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small Acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.