研究者詳細 - 山口　浩樹

論文 - 山口　浩樹

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Thermal Transpiration Flow: Molecular Dynamics Study from Dense to Dilute Gas 査読有り国際誌

Yamaguchi Hiroki, Kikugawa Gota

Fluids 9 巻 ( 1 ) 頁： 12 2023年12月

Some properties of a gas flow submitted to a temperature gradient 査読有り国際共著国際誌

M.V. Johansson, H. Yamaguchi, P. Perrier, I. Graur

International Journal of Heat and Mass Transfer 214 巻頁： 124372 2023年11月

Temperature gradient effects on gas flow through microporous media 査読有り国際共著国際誌

M.V. Johansson, K. Shahrivar, H. Yamaguchi, F. Topin, P. Perrier, I. Graur

Experimental Thermal and Fluid Science 148 巻頁： 110983 2023年10月

Experimental measurements of thermal and tangential momentum accommodation coefficients on solid surfaces: Water vapor in comparison with noble gases 査読有り国際誌

Yamaguchi H., Mori T., Ozaki Y., Matsuda Y., Niimi T.

International Journal of Heat and Mass Transfer 183 巻頁： 122195 2022年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Heat and Mass Transfer

In the high Knudsen number flows, like micro gaseous flows and flows in vacuum, the gas-surface interaction plays an important role. Among many gas species, water is a common and useful fluid in wide area of engineering applications, and it is one of the main residual gas components in the high vacuum environment. However, experimental measurements on the gas-surface interaction of water molecules are still limited. In this study, we focus on the accommodation coefficient, which represents the mean behavior of gas molecules on the scattering process from a surface. We measure the thermal accommodation coefficient (TAC) and the tangential momentum accommodation coefficient (TMAC) of water molecules. TAC is measured from the heat flux between two surfaces with different temperatures in vacuum. TMAC is derived through the viscous slip coefficient from the measurement of the mass flow rate through a microtube. To investigate the characteristics of water molecules clearly, the measured accommodation coefficients are compared with those of noble gases, helium, neon, and argon, measured with the same apparatus and procedures. For the accommodation coefficients of noble gases, TAC increases with increasing the molecular weight, while TMAC decreases, which are in good agreement with the previous studies. The TAC and TMAC of water are slightly larger than those estimated from the corresponding molecular weight of noble gases.

DOI： 10.1016/j.ijheatmasstransfer.2021.122195

Scopus

FRET measurement of polymer response under shear 査読有り国際誌

Iwao R., Yamaguchi H., Obata M., Matsuda Y.

Sensors 21 巻 ( 23 ) 2021年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sensors

Polymer solutions under shear flow are often observed in manufacturing processes. Classically, polymer behavior is represented by Kuhn’s bead-spring model, in which only the elongation of polymer chains is assumed. In recent years, the compression of polymer chains under shear flow has been reported. In this study, we investigated the behavior of polymer chains dissolved in various concentrations under shear flow. We measured the time variation of the fluorescence intensity emitted from a FRET (fluorescence resonance energy transfer) polymer, which enabled us to study the change in the distance between both ends of a polymer chain. The polymer chains appeared to stretch and compress depending on the concentration of the polymer solution. The results showed that the deformation of polymer chains was different from the classical theory. The FRET measurement is a promising diagnostic method for understanding the dynamics of polymer chains.

DOI： 10.3390/s21238033

Scopus

Extraction of Tangential Momentum and Normal Energy Accommodation Coefficients by Comparing Variational Solutions of the Boltzmann Equation with Experiments on Thermal Creep Gas Flow in Microchannels 査読有り国際共著国際誌

Missoni Tommaso, Yamaguchi Hiroki, Graur Irina, Lorenzani Silvia

FLUIDS 6 巻 ( 12 ) 2021年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fluids

In the present paper, we provide an analytical expression for the first-and second-order thermal slip coefficients, σ1,T and σ2,T, by means of a variational technique that applies to the integrodifferential form of the Boltzmann equation based on the true linearized collision operator for hard-sphere molecules. The Cercignani-Lampis scattering kernel of the gas-surface interaction has been considered in order to take into account the influence of the accommodation coefficients (αt, αn) on the slip parameters. Comparing our theoretical results with recent experimental data on the mass flow rate and the slip coefficient for five noble gases (helium, neon, argon, krypton, and xenon), we found out that there is a continuous set of values for the pair (αt, αn) which leads to the same thermal slip parameters. To uniquely determine the accommodation coefficients, we took into account a further series of measurements carried out with the same experimental apparatus, where the thermal molecular pressure exponent γ has been also evaluated. Therefore, the new method proposed in the present work for extracting the accommodation coefficients relies on two steps. First of all, since γ mainly depends on αt, we fix the tangential momentum accommodation coefficient in such a way as to obtain a fair agreement between theoretical and experimental results. Then, among the multiple pairs of variational solutions for (αt, αn), giving the same thermal slip coefficients (chosen to closely approximate the measurements), we select the unique pair with the previously determined value of αt . The analysis carried out in the present work confirms that both accommodation coefficients increase by increasing the molecular weight of the considered gases, as already highlighted in the literature.

DOI： 10.3390/fluids6120445

Web of Science

Scopus

Single-molecule tracking measurement of PDMS layer during curing process 査読有り国際誌

Iwao Ryo, Yamaguchi Hiroki, Niimi Tomohide, Matsuda Yu

PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 565 巻 2021年3月

Molecular dynamics study on flow structure inside a thermal transpiration flow field 査読有り国際誌

Yamaguchi Hiroki, Kikugawa Gota

PHYSICS OF FLUIDS 33 巻 ( 1 ) 2021年1月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Fluids

Thermal transpiration flow is a thermally driven flow from a cold part toward a hot part using a temperature gradient along a wall under a high Knudsen number condition. Many studies have used this type of flow as a pump for microtechnology. The flows adopted in these studies were, in most cases, in the slip or transitional regime. Accordingly, in this research, thermal transpiration flow through a two-dimensional channel with nanoscale clearance in the height direction was studied using the molecular dynamics method. The solid atoms composing the channel walls were explicitly considered. The center part of the nanochannel was controlled as a hot reservoir, whereas both ends of the nanochannel were kept cold. The temperatures of the channel wall atoms were also controlled based on their positions by linearly interpolating the temperature between the hot and cold reservoirs. Two Knudsen number conditions were adopted by changing the width of the computational cell. To study the mean velocity distribution inside the nanochannel, these simulations were performed for 10 ns. We successfully obtained a mean velocity distribution inside the nanochannel, showing the thermal transpiration flow in the vicinity of the channel wall using the pressure-driven counterflow at the center in the height direction even under the dense gas condition. The velocity profile across the nanochannel in the height direction indicated that thermal transpiration flow was induced in the adsorption layer of gas molecules on the channel wall under the dense gas condition.

DOI： 10.1063/5.0034146

Web of Science

Scopus

Dynamics of impact cratering on granular bed by hydrogel sphere 査読有り国際誌

Matsuda Yu, Kamiya Ryota, Yamaguchi Hiroki, Uchiyama Tomomi

PHYSICS OF FLUIDS 32 巻 ( 6 ) 2020年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Fluids

A lot of studies on the dynamics of a granular impact cratering by a liquid drop have been carried out. However, the results so far are controversial due to the complex impact dynamics of a liquid drop, such as deformation, splash, and penetration into the granular bed. In this study, we focused on the dynamics of the granular impact cratering by a hydrogel sphere, which deforms without splashing and penetrating. We investigated the maximal deformation time of the sphere and the lift-off time of the grains. Both the maximal deformation time and the lift-off time are similar to each other and depend on the -1/2 power of the Young's modulus of the hydrogel sphere. This power law of the maximum deformation time is the same as an impact of a gel sphere on a flat solid surface. The angle of the ejected curtain was evaluated. The angle is larger for the impact with small deformation of the sphere than that for the impact with large deformation, and the angle is less dependent on the free-fall height. We also investigated the distributions of the ejected grains using the grains dyed by a fluorescent dye. The distribution was visualized by the fluorescent images captured before and after the impact. At the crater rim, the number of the dyed grains flying to and away are balanced. The number of the dyed grains gathered at the dimensionless distance from the crater center of 1.15, where the distance is nondimensionalized by the crater radius, is the largest. This maximum value for the number of the gathered grains is larger for the impact with small deformation than that with large deformation. This result is consistent with the dependence of the impact mode on the angle of the ejected curtain.

DOI： 10.1063/5.0011406

Web of Science

Scopus

Simultaneous measurement of gas-liquid interface motion and temperature distribution on heated surface using temperature-sensitive paint 査読有り国際誌

Matsuda Yu, Kawanami Osamu, Orimo Riki, Uete Keigo, Watanabe Atsufumi, Egami Yasuhiro, Yamaguchi Hiroki, Niimi Tomohide

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 153 巻 2020年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Heat and Mass Transfer

We developed a simultaneous measurement technique for temperature distribution on a heated surface and gas-liquid interface motion of two-phase flows in microgap channel using temperature-sensitive paint (TSP). Since the TSP layer is optically transparent, the proposed method enables us to simultaneously measure the temperature distribution and the motion of gas-liquid interface through the TSP layer using an in-house stereoscope-like device. Since the refractive index of gas-phase differs from that of liquid-phase, the luminescent intensity of TSP in gas-phase varies from that in liquid-phase even though the temperatures are same in both phases. Then, we proposed a correction method for temperature distribution in gas-phase. To validate the proposed method, the temperature distribution measurements were conducted in liquid single-phase flow. The Nusselt numbers calculated from the measured temperatures were in good agreement with the Sieder-Tate equation. Then, we measured the temperature distributions for the boiling flows under several heated temperature conditions. The temperature distributions at growing bubble and bubble coalescence were successfully measured. TSP is useful method for investigating the temperature distribution in two-phase flows.

DOI： 10.1016/j.ijheatmasstransfer.2020.119567

Web of Science

Scopus

Measurement of Heat Transfer from Anodic Oxide Film on Aluminum in High Knudsen Number Flows 招待有り査読有り国際誌

H. Yamaguchi, K. Kito

Micromachines 11 巻 ( 3 ) 頁： 234 2020年2月

Design and demonstration of Knudsen heat pump without moving parts free from electricity 査読有り国際誌

K.Kugimoto, Y.Hirota, T.Yamauchi, H.Yamaguchi, T.Niimi

Applied Energy 250 巻頁： 1260-1269 2019年9月

Electrophoretic Separation on an Origami Paper-Based Analytical Device Using a Portable Power Bank 査読有り国際誌

Matsuda Yu, Sakai Katsunori, Yamaguchi Hiroki, Niimi Tomohide

SENSORS 19 巻 ( 7 ) 2019年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sensors (Switzerland)

The electrophoresis of ampholytes such as amino acids on a paper device is difficult because of the variation of pH distribution in time. On the basis of this observation, we propose a paper-based analytical device (PAD) with origami structure. By folding a filter paper, a low operation voltage of 5 V was achieved, where the power was supplied by a 5 V 1.5 A portable power bank through the USB type A receptacle. As a demonstration, we carried out the electrophoretic separation of pI markers (pI 5.5 and 8.7). The separation was achieved within 4 min before the pH distribution on the paper varied. Though the separation distance was small, it could be increased by expanding the origami structure. This result indicates that our proposed PAD is useful for electrophoretic separation on a paper device.

DOI： 10.3390/s19071724

Web of Science

Scopus

Impact cratering on a granular bed by hydrogel spheres having intermediate property between solid and liquid 査読有り国際誌

Matsuda Yu, Fukui Satoru, Kamiya Ryota, Yamaguchi Hiroki, Niimi Tomohide

PHYSICAL REVIEW E 99 巻 ( 3 ) 2019年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review E

We investigated the low speed impact on a granular bed by a hydrogel sphere and especially focused on the resultant crater diameter. Though the crater diameter depends only on the impact kinetic energy for the solid sphere impact cratering, it also depends on the elastic energy for the hydrogel sphere. The hydrogel sphere impact cratering is classified into two dynamics: small and large indentation of the sphere. For the small indentation, the crater diameter is proportional to the 1/4 power of the energy for ejecting granular materials, which is calculated by substituting the elastic energy stored in the sphere from the impact kinetic energy. Considering the force balance between the inertial force and the indentation, we derived the relation between the impact kinetic energy, Young's modulus, and the crater diameter. In the large limit of Young's modulus, the relation leads to the 1/4 power law observed in solid sphere impact. The dependency of Young's modulus on the crater diameter for the large indentation of the sphere is larger than the impact with small indentation.

DOI： 10.1103/PhysRevE.99.032906

Web of Science

Scopus

Measurement of conductive heat transfer through rarefied binary gas mixtures 査読有り国際誌

Yamaguchi Hiroki, Hosoi Jumpei, Matsuda Yu, Niimi Tomohide

VACUUM 160 巻頁： 164 - 170 2019年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Vacuum

The conductive heat transfer through a rarefied binary gas mixture of helium and argon is experimentally investigated as a function of a molar fraction. The heat flux is measured from the free-molecular to near free-molecular flow regimes, and it is analyzed both in dimensional and dimensionless forms to clarify the effect from the gas-surface interaction. Then, the thermal accommodation coefficient is obtained by assuming a gas mixture as a single “virtual” species gas. The measured thermal accommodation coefficients for single component gases of helium and argon show good agreement with our previous results and data in literature. The thermal accommodation coefficient for a binary gas mixture is compared with the theoretical value derived in the free-molecular flow regime as a superposition of an independent heat transfer by each gas component. The measured results are well explained by the theory. However, there is a little discrepancy between them, suggesting variation in the thermal accommodation coefficient with a molar fraction in flow regimes other than the free-molecular flow regime.

DOI： 10.1016/j.vacuum.2018.11.021

Web of Science

Scopus

A novel heat pump system using a multi-stage Knudsen compressor 査読有り国際誌

K. Kugimoto, Y. Hirota, T. Yamauchi, H. Yamaguchi, T. Niimi

International Journal of Heat and Mass Transfer 127 巻頁： 84-91 2018年12月

Estimation of diffusive states from single-particle trajectory in heterogeneous medium using machine-learning methods 査読有り国際誌

Matsuda Yu, Hanasaki Itsuo, Iwao Ryo, Yamaguchi Hiroki, Niimi Tomohide

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 20 巻 ( 37 ) 頁： 24099-24108 - 24108 2018年10月

Performance prediction method for a multi-stage Knudsen pump 査読有り国際誌

K. Kugimoto, Y. Hirota, Y. Kizaki, H. Yamaguchi, T. Niimi

Physics of Fluids 29 巻 ( 12 ) 頁： 122002 2017年12月

Fine printing of pressure- and temperature-sensitive paints usingcommercial inkjet printer 査読有り国際誌

Y. Matsuda, T. Kameya, Y. Suzuki, Y. Yoshida, Y. Egami, H. Yamaguchi, T. Niimi

Sensors and Actuators B: Chemical 250 巻頁： 563-568 2017年10月

Molecular-dynamics study on characteristics of energy and tangential momentum accommodation coefficients 査読有り国際誌

H. Yamaguchi, Y. Matsuda, T. Niimi

Physical Review E 96 巻 ( 1 ) 頁： 013116 2017年7月

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