Motoyasu Kamata
University of Tokyo
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Motoyasu Kamata.
International Journal of Ventilation | 2004
Masaaki Ohba; Takashi Kurabuchi; Endo Tomoyuki; Yoshihiko Akamine; Motoyasu Kamata; Aya Kurahashi
Abstract The proposed local dynamic similarity model of cross-ventilation predicted ventilation flow rates moreb accurately than the conventional orifice flow model assuming constant discharge coefficients when discharge coefficients actually decreased with change of wind direction. This model was used to develop a new method for evaluating the ventilation performance of window openings. The obstructive effect of model size on flow fields in a wind tunnel was avoided by installing the opening parallel to the wind tunnel floor. The ventilation performance for various types of inflow openings was assessed by the ventilation performance evaluation system. The discharge coefficient was expressed by an approximate expression using dimensionless room pressure PR*. A ventilation performance database was thus produced. For the field experiment in a full-sized house, it was found that about 60% of all wind data were in the range of |PR*| < 5. This reveals that the discharge coefficient decreases frequently in actual wind.
International Journal of Ventilation | 2006
Takashi Kurabuchi; Yoshihiko Akamine; Masaaki Ohba; Tomoyuki Endo; Tomonobu Goto; Motoyasu Kamata
Abstract A study was performed on the effects of porosity on discharge coefficient and airflow characteristics under the condition where uniform approaching flow directly faces to and enters the opening by using wind tunnel experiment and CFD analysis. The evaluation was performed on porosities in the range 0.4% - 64%. The results of wind tunnel experiments suggest that the discharge coefficient increases when the porosity is higher. The results of CFD analysis reveal that the contraction of airflow when it passes through the opening is correlated with discharge coefficient, and that the discharge coefficient increases when flow contraction does not occur. When porosity increases, the retardment of the streamtube ceases to occur in the region upstream of the opening, and this leads to the elimination of flow contraction, hence the increase of discharge coefficient. When we evaluated the limitation of application of the local dynamic similarity model on porosity, the effectiveness of the model was confirmed well when the porosity was 16% or lower regardless of wind direction. The validity of the model was also confirmed under the condition where airflow goes along the wall surface before reaching the opening even when the porosity was 36% or more.
International Journal of Ventilation | 2004
Yoshihiko Akamine; Takashi Kurabuchi; Masaaki Ohba; Tomoyuki Endo; Motoyasu Kamata
Abstract In the present study, a numerical simulation to simulate an experiment for evaluating the cross-ventilation performance at an inflow opening by using Large Eddy Simulation (LES), the standard k-ε model, and Durbin‘s k-ε model was performed. Results showed that too much turbulent kinetic energy was produced at the leeward opening frame in the standard k-ɛ model. However, Durbin‘s k-ε model improved this defect, and reproduced the wind tunnel results fairly well, as did the LES approach. Following on from this comparison, Durbin’s k-ε model was applied to the analysis of the air flow characteristics from the viewpoint of aspect ratio, opening thickness, and whether a louver was present or not. From the results it was concluded that static pressure increase was induced by the collision of the inflowing air with the leeward opening frame. This static increase caused a decrease in the discharge coefficient. There was little influence on the cross-ventilation flow rate when the louver angle was perpendicular to the opening surface and when it was installed on the inside of the opening.
International Journal of Ventilation | 2004
Tomoyuki Endo; Takashi Kurabuchi; Masaaki Ohba; Yoshihiko Akamine; Motoyasu Kamata
Abstract A Local Dynamic Similarity Model, applicable to dynamic similarity of cross-ventilation, has been applied to outflow openings. Cross-ventilation performance at the openings on the outflow side has been evaluated, and the structure of air flows around the outflow openings has been studied by LES and wind tunnel experiments. It was found that LES reproduces the wind tunnel experiment results fairly well, such as the extensive increase of discharge coefficient in a small region where dimensionless room pressure, PR*, is low. The evaluation of the pressure field by LES revealed that the remainder of the dynamic pressure in the air flows and the change of the pressure field around the outflow openings have a strong influence on the discharge coefficient. Furthermore, by identifying the configuration of the stream tube of the ventilation air flow, it was found that the discharge coefficient is changed depending on how the air flows exit. In general, dynamic pressure, Pt, tangential to the wall surface at the outflow openings is considered to be lower than that at the inflow side. The occurrence frequency of PR* was investigated by a full-scale experiment, and it was elucidated that the region of PR* where the discharge coefficient is extensively decreased develops only very rarely.
Journal of Environmental Engineering (transactions of Aij) | 2013
Satoru Ozawa; Toshiya Iwamatsu; Motoyasu Kamata; Tohru Yoshikawa; Noriyoshi Ichikawa
�� ��� ������������������������������ �������� ��� �������������������� ������������������������������� ������ � ����������������������� ������������������������������� ������������������� ������������ ������������������������������ ������ ������������������������������ ������������������������������ ������������������������������ ������������������������ ������������������������������ ������������������������������ ��������������������������� ������������������������������� ������������������������������ ��������� ��� ���������������������� ������������������������������ ������������������������������ ���������������� ������������������������������ ������������������������������ ������������������������������ ������������������������������� ������������������������������ ��������������
Hvac&r Research | 2011
Asako Hasegawa; Hiromi Komine; Motoyasu Kamata
In Japan, there are currently no standards or codes to test the performance of portable air cleaners in removing gaseous formaldehyde (HCHO) and volatile organic compounds, which have been classified as indoor pollutants that affect human health. The purpose of this study was to establish a method to test the performance of portable air cleaners, which are used to remove gaseous chemical substances. The method developed in this study was proposed before the ANSI/AHAM AC-1 was established in 2002. The proposed simple gas generator, original “single-pass” testing method, and results for five air cleaning devices offer useful examples for related studies and might help improve current standards.
Archive | 2008
Motoyasu Kamata; Masayuki Mae
In Japan, since World War II, better water systems have been developed and the amount of water used has increased rapidly. Nationally, rainfall is relatively plentiful and the cost of water service is not expensive in many regions. So people are not very sensitive about water conservation in regards to buildings. In that context, the main interest of designing the water system in a building has been to assure comfort by determining the proper number of fixtures and the system capacity.
Archive | 2001
Motoyasu Kamata; Akiyoshi Kubota; Masayuki Mae; Minako Nabeshima; Hideyo Ninomiya; Satoshi Nishiguchi; 秀與 二宮; 真之 前; 明美 窪田; 智 西口; 美奈子 鍋島; 元康 鎌田
International Journal of Ventilation | 2005
Takashi Kurabuchi; Masaaki Ohba; Tomonobu Goto; Yoshihiko Akamine; Tomoyuki Endo; Motoyasu Kamata
Journal of architecture,planning and environmental engineering | 1999
Yasuo Kuwasawa; Motoyuki Saito; Motoyasu Kamata; Yoshitaka Chida