Bio


Maeda's research combines high-performance computing, modeling, data analysis, control, and companion experiments to address complex flow phenomena. He actively works on biomedical, energy, and propulsion applications, and on interdisciplinary research.

His current major research and teaching activities are conducted in the Center for Turbulence Research (https://ctr.stanford.edu) and the Predictive Science Academic Alliance Program Center (https://insieme.stanford.edu).

Maeda obtained his BS from the University of Tokyo in 2013, and MS and PhD from Caltech in 2014 and 2018, all in Mechanical Engineering. He was a postdoctoral fellow in the Center for Turbulence Research from 2019 to 2020.

Academic Appointments


  • Phys Sci Res Assoc, Mechanical Engineering

Administrative Appointments


  • Research Associate, Center for Turbulence Research, Stanford University (2020 - Present)
  • Postdoctoral Fellow, Center for Turbulence Research, Stanford University (2019 - 2020)

Honors & Awards


  • Center for Turbulence Research Postdoctoral Fellowship, Stanford University (2019)
  • Richard Bruce Chapman Memorial Award, California Institute of Technology (2018)
  • Funai Overseas Scholarship Award, Funai Foundation for Information Technology (2013 - 2018)

Professional Education


  • Ph.D., California Institute of Technology, Mechanical Engineering (2018)
  • M.S., California Institute of Technology, Mechanical Engineering (2014)
  • B.S., The University of Tokyo, Mechanical Engineering (2013)

Patents


  • Shoji Takeuchi, Hiroaki Onoe, Masahiro Takinoue, Kazuki Maeda, Kiichi Inamori. "Japan Patent JP5830253B2 Apparatus and method of gelling liquid", Dec 9, 2015

All Publications


  • MFC: An open-source high-order multi-component, multi-phase, and multi-scale compressible flow solver. Computer physics communications Bryngelson, S. H., Schmidmayer, K., Coralic, V., Meng, J. C., Maeda, K., Colonius, T. 2021; 266

    Abstract

    MFC is an open-source tool for solving multi-component, multi-phase, and bubbly compressible flows. It is capable of efficiently solving a wide range of flows, including droplet atomization, shock-bubble interaction, and bubble dynamics. We present the 5- and 6-equation thermodynamically-consistent diffuse-interface models we use to handle such flows, which are coupled to high-order interface-capturing methods, HLL-type Riemann solvers, and TVD time-integration schemes that are capable of simulating unsteady flows with strong shocks. The numerical methods are implemented in a flexible, modular framework that is amenable to future development. The methods we employ are validated via comparisons to experimental results for shock-bubble, shock-droplet, and shock-water-cylinder interaction problems and verified to be free of spurious oscillations for material-interface advection and gas-liquid Riemann problems. For smooth solutions, such as the advection of an isentropic vortex, the methods are verified to be high-order accurate. Illustrative examples involving shock-bubble-vessel-wall and acoustic-bubble-net interactions are used to demonstrate the full capabilities of MFC.

    View details for DOI 10.1016/j.cpc.2020.107396

    View details for PubMedID 34168375

    View details for PubMedCentralID PMC8218895

  • Viscid-inviscid interactions of pairwise bubbles in a turbulent channel flow and their implications for bubble clustering JOURNAL OF FLUID MECHANICS Maeda, K., Date, M., Sugiyama, K., Takagi, S., Matsumoto, Y. 2021; 919
  • Analysis of core-noise contributions in a realistic gas-turbine combustor operated near lean blow-out PROCEEDINGS OF THE COMBUSTION INSTITUTE Shao, C., Maeda, K., Ihme, M. 2021; 38 (4): 6203-6211
  • Controlling the dynamics of cloud cavitation bubbles through acoustic feedback Physical Review Applied Maeda, K., Maxwell, A. D. 2021; 15:034033
  • Robust flow reconstruction from limited measurements via sparse representation PHYSICAL REVIEW FLUIDS Callaham, J., Maeda, K., Brunton, S. L. 2019; 4 (10)
  • Bubble cloud dynamics in an ultrasound field JOURNAL OF FLUID MECHANICS Maeda, K., Colonius, T. 2019; 862: 1105–34
  • High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone. The Journal of the Acoustical Society of America Pishchalnikov, Y. A., Behnke-Parks, W. M., Schmidmayer, K. n., Maeda, K. n., Colonius, T. n., Kenny, T. W., Laser, D. J. 2019; 146 (1): 516

    Abstract

    Ultra-high-speed video microscopy and numerical modeling were used to assess the dynamics of microbubbles at the surface of urinary stones. Lipid-shell microbubbles designed to accumulate on stone surfaces were driven by bursts of ultrasound in the sub-MHz range with pressure amplitudes on the order of 1 MPa. Microbubbles were observed to undergo repeated cycles of expansion and violent collapse. At maximum expansion, the microbubbles' cross-section resembled an ellipse truncated by the stone. Approximating the bubble shape as an oblate spheroid, this study modeled the collapse by solving the multicomponent Euler equations with a two-dimensional-axisymmetric code with adaptive mesh refinement for fine resolution of the gas-liquid interface. Modeled bubble collapse and high-speed video microscopy showed a distinctive circumferential pinching during the collapse. In the numerical model, this pinching was associated with bidirectional microjetting normal to the rigid surface and toroidal collapse of the bubble. Modeled pressure spikes had amplitudes two-to-three orders of magnitude greater than that of the driving wave. Micro-computed tomography was used to study surface erosion and formation of microcracks from the action of microbubbles. This study suggests that engineered microbubbles enable stone-treatment modalities with driving pressures significantly lower than those required without the microbubbles.

    View details for DOI 10.1121/1.5116693

    View details for PubMedID 31370610

    View details for PubMedCentralID PMC6660306

  • Modeling and numerical simulation of the bubble cloud dynamics in an ultrasound field for burst wave lithotripsy. Proceedings of meetings on acoustics. Acoustical Society of America Maeda, K., Colonius, T., Maxwell, A., Kreider, W., Bailey, M. 2018; 35 (1)

    Abstract

    Modeling and numerical simulation of bubble clouds induced by intense ultrasound waves are conducted to quantify the effect of cloud cavitation on burst wave lithotripsy, a proposed non-invasive alternative to shock wave lithotripsy that uses pulses of ultrasound with an amplitude of O(1) MPa and a frequency of O(100) kHz. A unidirectional acoustic source model and an Eulerian-Lagrangian method are developed for simulation of ultrasound generation from a multi-element array transducer and cavitation bubbles, respectively. Parametric simulations of the spherical bubble cloud dynamics reveal a new scaling parameter that dictates both the structure of the bubble cloud and the amplitude of the far-field, bubble-scattered acoustics. The simulation further shows that a thin layer of bubble clouds nucleated near a kidney stone model can shield up to 90% of the incoming wave energy, indicating a potential loss of efficacy during the treatment due to cavitation. Strong correlations are identified between the far-field, bubble-scattered acoustics and the magnitude of the shielding, which could be used for ultrasound monitoring of cavitation during treatments. The simulations are validated by companion experiments in vitro.

    View details for DOI 10.1121/2.0000946

    View details for PubMedID 32612742

    View details for PubMedCentralID PMC7328995

  • Energy shielding by cavitation bubble clouds in burst wave lithotripsy JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Maeda, K., Maxwell, A. D., Colonius, T., Kreider, W., Bailey, M. R. 2018; 144 (5): 2952–61

    Abstract

    Combined laboratory experiment and numerical simulation are conducted on bubble clouds nucleated on the surface of a model kidney stone to quantify the energy shielding of the stone caused by cavitation during burst wave lithotripsy (BWL). In the experiment, the bubble clouds are visualized and bubble-scattered acoustics are measured. In the simulation, a compressible, multi-component flow solver is used to capture complex interactions among cavitation bubbles, the stone, and the burst wave. Quantitative agreement is confirmed between results of the experiment and the simulation. In the simulation, a significant shielding of incident wave energy by the bubble clouds is quantified. The magnitude of shielding can reach up to 90% of the energy of the incoming burst wave that otherwise would be transmitted into the stone, suggesting a potential loss of efficacy of stone comminution. There is a strong correlation between the magnitude of the energy shielding and the amplitude of the bubble-scattered acoustics, independent of the initial size and the void fraction of the bubble cloud within a range addressed in the simulation. This correlation could provide for real-time monitoring of cavitation activity in BWL.

    View details for DOI 10.1121/1.5079641

    View details for Web of Science ID 000454102300049

    View details for PubMedID 30522301

    View details for PubMedCentralID PMC6258362

  • Eulerian -Lagrangian method for simulation of cloud cavitation JOURNAL OF COMPUTATIONAL PHYSICS Maeda, K., Colonius, T. 2018; 371: 994–1017

    Abstract

    We present a coupled Eulerian-Lagrangian method to simulate cloud cavitation in a compressible liquid. The method is designed to capture the strong, volumetric oscillations of each bubble and the bubble-scattered acoustics. The dynamics of the bubbly mixture is formulated using volume-averaged equations of motion. The continuous phase is discretized on an Eulerian grid and integrated using a high-order, finite-volume weighted essentially non-oscillatory (WENO) scheme, while the gas phase is modeled as spherical, Lagrangian point-bubbles at the sub-grid scale, each of whose radial evolution is tracked by solving the Keller-Miksis equation. The volume of bubbles is mapped onto the Eulerian grid as the void fraction by using a regularization (smearing) kernel. In the most general case, where the bubble distribution is arbitrary, three-dimensional Cartesian grids are used for spatial discretization. In order to reduce the computational cost for problems possessing translational or rotational homogeneities, we spatially average the governing equations along the direction of symmetry and discretize the continuous phase on two-dimensional or axi-symmetric grids, respectively. We specify a regularization kernel that maps the three-dimensional distribution of bubbles onto the field of an averaged two-dimensional or axi-symmetric void fraction. A closure is developed to model the pressure fluctuations at the sub-grid scale as synthetic noise. For the examples considered here, modeling the sub-grid pressure fluctuations as white noise agrees a priori with computed distributions from three-dimensional simulations, and suffices, a posteriori, to accurately reproduce the statistics of the bubble dynamics. The numerical method and its verification are described by considering test cases of the dynamics of a single bubble and cloud cavitaiton induced by ultrasound fields.

    View details for DOI 10.1016/j.jcp.2018.05.029

    View details for Web of Science ID 000438393900047

    View details for PubMedID 30739952

    View details for PubMedCentralID PMC6364854

  • Transient Cavitation in Pre-Filled Syringes During Autoinjector Actuation 10th International Symposium on Cavitation (CAV2018) Veilleux, J., Maeda, K., Colonius, T., Shepherd, J. E. 2018

    View details for DOI 10.1115/1.861851_ch203

  • Experimental observations and numerical modeling of lipid-shell microbubbles with calcium-adhering moieties for minimally-invasive treatment of urinary stones. Proceedings of meetings on acoustics. Acoustical Society of America Pishchalnikov, Y. A., Behnke-Parks, W. n., Maeda, K. n., Colonius, T. n., Mellema, M. n., Hopcroft, M. n., Luong, A. n., Wiener, S. n., Stoller, M. L., Kenny, T. n., Laser, D. J. 2018; 35 (1)

    Abstract

    A novel treatment modality incorporating calcium-adhering microbubbles has recently entered human clinical trials as a new minimally-invasive approach to treat urinary stones. In this treatment method, lipid-shell gas-core microbubbles can be introduced into the urinary tract through a catheter. Lipid moities with calcium-adherance properties incorporated into the lipid shell facilitate binding to stones. The microbubbles can be excited by an extracorporeal source of quasi-collimated ultrasound. Alternatively, the microbubbles can be excited by an intraluminal source, such as a fiber-optic laser. With either excitation technique, calcium-adhering microbubbles can significantly increase rates of erosion, pitting, and fragmentation of stones. We report here on new experiments using high-speed photography to characterize microbubble expansion and collapse. The bubble geometry observed in the experiments was used as one of the initial shapes for the numerical modeling. The modeling showed that the bubble dynamics strongly depends on bubble shape and stand-off distance. For the experimentally observed shape of microbubbles, the numerical modeling showed that the collapse of the microbubbles was associated with pressure increases of some two-to-three orders of magnitude compared to the excitation source pressures. This in-vitro study provides key insights into the use of microbubbles with calcium-adhering moieties in treatment of urinary stones.

    View details for DOI 10.1121/2.0000958

    View details for PubMedID 32440311

    View details for PubMedCentralID PMC7241592

  • An Equation of State Tabulation Approach for Injectors with Non-Condensable Gases: Development and Analysis 10th International Symposium on Cavitation (CAV2018) Bode, M., Satcunanathan, S., Maeda, K., Colonius, T., Pitsch, H. 2018

    View details for DOI 10.1115/1.861851_ch10

  • A source term approach for generation of one-way acoustic waves in the Euler and Navier-Stokes equations WAVE MOTION Maeda, K., Colonius, T. 2017; 75: 36–49

    Abstract

    We derive a volumetric source term for the Euler and Navier-Stokes equations that mimics the generation of unidirectional acoustic waves from an arbitrary smooth surface in three-dimensional space. The model is constructed as a linear combination of monopole and dipole sources in the mass, momentum, and energy equations. The singular source distribution on the surface is regularized on a computational grid by convolution with a smeared Dirac delta function. The source is implemented in the Euler equations using a Cartesian-grid finite-volume WENO scheme, and validated by comparing with analytical solution for unidirectional planar and spherical acoustic waves. Using the scheme, we emulate a spherical piezoelectric transducer and a multi-array transducer to simulate focused ultrasound fields in water. The simulated ultrasound fields show favorable agreement with previous experiments.

    View details for DOI 10.1016/j.wavemoti.2017.08.004

    View details for Web of Science ID 000413797700004

    View details for PubMedID 30270952

    View details for PubMedCentralID PMC6159925

  • Observation and Manipulation of a Capillary Jet in a Centrifuge-Based Droplet Shooting Device MICROMACHINES Maeda, K., Onoe, H., Takinoue, M., Takeuchi, S. 2015; 6 (10): 1526–33

    View details for DOI 10.3390/mi6101436

    View details for Web of Science ID 000364240500011

  • Modeling and experimental analysis of acoustic cavitation bubbles for Burst Wave Lithotripsy Maeda, K., Kreider, W., Maxwell, A., Cunitz, B., Colonius, T., Bailey, M., IOP IOP PUBLISHING LTD. 2015
  • Controlled Synthesis of 3D Multi-Compartmental Particles with Centrifuge-Based Microdroplet Formation from a Multi-Barrelled Capillary ADVANCED MATERIALS Maeda, K., Onoe, H., Takinoue, M., Takeuchi, S. 2012; 24 (10): 1340–46

    Abstract

    Controlled synthesis of micro multi-compartmental particles using a centrifuge droplet shooting device (CDSD) is reported. Sodium alginate solutions introduced in a multi-barreled capillary form droplets at the capillary orifice under ultrahigh gravity and gelify in a CaCl(2) solution. The size, shape, and compartmentalization of the particles are controlled. Co-encapsulation of Jurkat cells and magnetic colloids into Janus particles is demonstrated. The Janus particles present sensitive reaction toward magnetic fields, while the viability of the encapsulated cells is 91%.

    View details for DOI 10.1002/adma.201102560

    View details for Web of Science ID 000301112200021

    View details for PubMedID 22311473