||Contribution of Combustion Air Preheating to Operation of an Industrial Waste Treatment Plant.
||Shuji Hironaka, Saki Manabe, Yuki Fujisawa, Gen Inoue, Yosuke Matsukuma, Masaki Minemoto, The direct numerical simulation of the rising gas bubble with the volume of fluid (VOF) method, ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011
Fluids and Thermal Systems; Advances for Process Industries, 10.1115/imece2011-63377, 845-854, 2011, A gas-liquid two phase flow is complicated and it has not been understood well thus far, in spite of extensive investigation. Numerical simulation is a potential approach to understand this phenomenon. Although a number of studies have been conducted to understand the behavior of bubbles on the basis of computational fluid dynamics (CFD), it is difficult to completely simulate a complicated three-phase flow, including coalescence and breakup of bubbles. Although the two-fluid model based on the semi-empirical model can well estimate the actual behavior of the system in which the equations are derived, the estimation over the applicable region of equations does not always agree with the actual result. Since the 1960s, various procedures have been proposed to directly track the free surface between two phases, for example, the adaptive mesh method and the particle method. Although each of these methods has certain advantages and disadvantages, the volume of fluid (VOF) method is the most acceptable method for capturing the free surface accurately and clearly. However, a concern related to this method is the maintenance of a constant volume of the fluid. In this study, a simulation code using the VOF method is developed in order to estimate the behavior of bubbles in a vertical pipe. Further, an offset of the volume fraction is introduced to stably calculate and minimize the volume fluctuation. The effect of the surface tension is also built into the program in order to estimate the behavior of the bubbles rising through the liquid medium. The simulations of the collapsed water column and a single rising bubble are conducted with the proposed simulation code. Consequently, we confirm that these results fairly agree with the experimental ones..
||Shuji Hironaka, Gen Inoue, Jun Fukai, Yoshifumi Tsuge, Modeling of the evaporation of the polymer slurry in the porous media, Engineering Sciences and Fundamentals 2017 - Core Programming Area at the 2017 AIChE Annual Meeting
Engineering Sciences and Fundamentals 2017 - Core Programming Area at the 2017 AIChE Annual Meeting, 2, 584-591, 2017.01.
||Gu Kim, Jun Fukai, Shuji Hironaka, Rheological modeling of nanoparticles in a suspension with shear flow, Applied Chemistry for Engineering, 10.14478/ace.2019.1040, 30, 4, 445-452, 2019.08, Shear thickening is an intriguing phenomenon in the fields of chemical engineering and rheology because it originates from complex situations with experimental and numerical measurements. This paper presents results from the numerical modeling of the particle-fluid dynamics of a two-dimensional mixture of colloidal particles immersed in a fluid. Our results reveal the characteristic particle behavior with an application of a shear force to the upper part of the fluid domain. By combining the lattice Boltzmann and discrete element methods with the calculation of the lubrication forces when particles approach or recede from each other, this study aims to reveal the behavior of the suspension, specifically shear thickening. The results show that the calculated suspension viscosity is in good agreement with the experimental results. Results describing the particle deviation, diffusivity, concentration, and contact numbers are also demonstrated..
||Gu Kim, Jun Fukai, Shuji Hironaka, Numerical study of various shape aggregations of carbon black in suspension with shear flow, Polymer (Korea), 10.7317/pk.2019.43.5.741, 43, 5, 741-749, 2019.09, Aggregates of carbon black with various shapes in a suspension were investigated to understand their behavior in fluid flow. At a lower aspect ratio, the particles exhibited tumbling or rotational motion, and the fluid flow was deflected in regions where the density of particles was higher. The contact between the particles promoted partial particle grouping when the aspect ratios of the particles were low. The average transitional motion of the particles was greatest at the lowest aspect ratio case. This led to weaker rearrangement event than those when the particles were nearly spherical. The elongated particles could act as bridges to promote the formation of particle groups. We believe that our study provides insight for suspensions containing particles with various shapes, which can be used to control the suspensions Theologically..
||G. Kim, Jun Fukai and Shuji Hironaka, Rheological modeling of nanoparticles in a suspension with shear flow, Applied Chemistry for Engineering, 30, 4, 445-452, 2019.06.
||G. Kim, Jun Fukai and Shuji Hironaka, Numerical study of various shape aggregations of carbon black in suspension with shear flow, Polymer, 43, 5, 741-749, 2019.07.