Optimal control of turbulent transport phenomena
For the purposes of reducing skin friction drag and enhancing heat transfer, we are developing new strategies for controlling turbulent boundary layers by combining massively parallel computation and optimal control theory. These techniques are keys for effective energy utilization through energy savings in various thermo-fluids systems such as aircrafts, marine vessels, automobiles etc. [MORE]
Optimal control of wall turbulence with wall blowing and suction
(left) uncontrolled and (right) controlled
The blue and white contours show low speed regions and vortex cores, respectively.
The color on the wall in the right figure shows the optimal control input.
The streamwise velocity and the temperature in a fully developed turbulent channel flow subject to traveling wave-like wall blowing and suction
(Top) uncontrolled, (Bottom) controlled
Reference: Kaithakkal et al. (J. Fluid Mech., 2020)
Topology/shape optimization of heat transfer surfaces
Recently, recovering heat from natural energy such as geothermal and solar energy as well as exhaust from chemical and power plants attracts much attention, since it could be converted to more valuable energy form such as kinetic and electric energy. We develop and validate new shape and topology optimization strategies in order to further enhance the performances of heat transfer surfaces for the above applications. [MORE]
(left) Shape optimization and (right) topology optimazation of oblique wavy wall for enhancing heat transfer and mitigating pressure loss
The color on the wall shows the local sensitivity to a cost functional.
Remodeling of vascular network in biological systems
In biological systems, vascular network plays essential roles in transporting oxygen, nutrients and medicine to organs as well as removing carbon dioxide and other wastes. For these purposes, it is hypothesized that the structure of the vascular network has been optimized through the course of evolution. We aim at clarifying the principle of optimizing shapes in biological systems by deepening our understanding of vascular formation under close collaborations with experts in biology and medicine. [MORE]
3D Reconstruction of Zebrafish brain vasculature
Yellow line: center line of each vessel
White dot: Node on each centerline, Red dot: branching point, Blue dot: end point
(Collaboration with Dr. Hiroyuki Nakajima at National Cerebral and Cardiovascular Center)
Estimation of turbulent states from limited measurements
A turbulent flow field and associated thermal and concentration fields exhibit complex spatio-temporal distributions due to their strong non-linearity and large degrees of freedom. Meanwhile, measurement data obtained from environments are always quite limited. Recently, rapid development of IoT allows us to access various sensor information. We are developing a framework to integrated various types of measurements to numerical simulations in order to establish new environmental monitoring systems for the atmosphere and the ocean. [MORE]
Reconstruction of a turbulent state based on randomly distributed sensors
Left) True flow state Right) Estimated flow state by integrating limited measurement data into simulation
It can be seen that the estimated state in the right figure converges to the true state with increasing the number of sensing points shown by yellow dots.
Reference: Suzuki & Hasegawa, J. Fluid Mech. (2017), Liu & Hasegawa (2020)
Scalar source estimation based on limited sensing information in turbulent environment
(Left) forward simulation, (Right) Adjoint simulation
Reference: Cerizza et al. (Flow Turb. Comb., 2016), Wang et al. (J. Fluid Mech., 2019)
Prediction and control of microparticles in microfluids
In micro-scales, a surface force becomes more dominant over a volume force, and thereby different flow physics appear from those observed in micro-scales. We are working on prediction and control of microparticles in fluids for developing a new micromixer used in biochemical analyses, and also fabrication processes of various energy devices such as fuel cells and lithium-ion batteries. [MORE]
(left)Particle behavior and (right)simulation of flow and particle trajectories around array of micro-pillars subject to rotational vibration
(Collaboration with Prof. Hiroaki Suzuki at Chuo University)
Reference: Kaneko et al. (Micromachines, 2018)