S. Murakami’s research while affiliated with Tohoku University and other places

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Publications (64)


LES Prediction of Gas Diffusion Near Building using Dynamic Mixed SGS Model based on a Composite Grid System
  • Conference Paper

October 1997

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6 Reads

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2 Citations

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S. Murakami

The turbulent diffusion of gaseous contaminant near a building model is predicted by Large Eddy Simulations (LES) using a Dynamic Mixed SGS model (DM model ) with the aid of the composite grid technique. The results using a composite grid show better agreement with the experiment than does the case using a single grid. Some discrepancies from the experimental results are observed in the results of the standard Smagorinsky model (S model) with a composite grid. These discrepancies are reduced remarkably by using the DM model.


Generation of velocity fluctuations for inflow boundary condition of LES

April 1997

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190 Reads

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125 Citations

Journal of Wind Engineering and Industrial Aerodynamics

In this study, inflow turbulence for LES was generated by the method of Hoshiya [Proc. JSCE 204 (1972) 121–128] based on Monte Carlo simulation considering power spectral density and cross-spectral density as targets. The generated inflow turbulence was modified to satisfy the continuity equation by divergence-free operation based on the method of Shirani et al. [Report TF-15, 1981, Mechanical Engieering Department, Stanford University]. As a result, inflow turbulence satisfied the prescribed spatial correlation and power spectral density and the level of velocity divergence was sufficiently reduced. To confirm the applicability of generated inflow turbulence, it was used as the inflow boundary condition for simulating decaying isotropic turbulence with the same conditions as the experiment by G. Comte-Bellot and S. Corrsin [J. Fluid Mech. 48 (1971) 273–337]. Decay of turbulence kinematic energy in the streamwise direction was reproduced well by LES using generated inflow turbulence.



CFD prediction of gaseous diffusion around a cubic model using a dynamic mixed SGS model based on composite grid technique

April 1997

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59 Reads

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56 Citations

Journal of Wind Engineering and Industrial Aerodynamics

Turbulent diffusion of gaseous contaminant near a cubic-shaped building model is predicted by LES using a Dynamic Mixed SGS (DM) model with the aid of the composite grid technique. The results obtained using a composite grid show better agreement with experiment than does the case using a single grid. Some discrepancies from the experimental results are observed in the results of the standard Smagorinsky model with a composite grid. These discrepancies are improved remarkably by using the DM model.



Development of new k−ε model for flow and pressure fields around bluff body

April 1997

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119 Reads

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185 Citations

Journal of Wind Engineering and Industrial Aerodynamics

It is well known that applications of the standard k−ε model to flowfields around bluff-shaped bodies, often yield serious errors such as overestimation of turbulence kinetic energy k in the impinging region. Murakami, Mochida and Kondo have proposed a new k−ε model which resolves these problems by modifying the expression for eddy viscosity approximation. This paper examines the applicability of this new k−ε model (MMK model) to flowfields around three types of bluff bodies, i.e. a 2D square rib, a cube and a low-rise building model with 1 : 1 : 0.5 shape. The first half of the paper investigates the accuracy of the MMK model in reproducing turbulence characteristics around a bluff body. Results of the MMK model are compared precisely with those of the standard k−ε model, a revised k−ε model proposed by Launder and Kato (LK model) and wind tunnel tests for flow fields around a 2D square rib and a cube. The MMK model is also applied to predicting surface pressures on a low-rise building model with 1 : 1 : 0.5 shape with various wind angles including an oblique one. The accuracy and applicability of the MMK model to wind engineering problems are then discussed by comparing its results with those of the standard k−ε model and of the wind tunnel tests.



New low-Reynolds-number k-ε model including damping effect due to buoyancy in a stratified flow field

November 1996

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26 Reads

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46 Citations

International Journal of Heat and Mass Transfer

A new k-ε model which includes damping effect on vertical turbulent transport due to thermal stratification is proposed. The proposed model was tested by application to two kinds of two-dimensional thermally stratified flow fields. One is a high-Reynolds-number open channel flow, and the other is a low-Reynolds-number flowfield within an enclosure. The new model also includes low-Reynolds-number treatment which is effective not only in the vicinity of the wall, but also apart from the wall. With the aid of this new low-Reynolds-number treatment, the proposed k-ε model becomes applicable to a flowfield which includes both turbulent area and pseudo-laminar area caused by thermal stratification. The agreement between the results given from the new k-ε model and the experimental results was rather good.


Computational Wind Engineering

January 1996

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57 Reads

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108 Citations

Journal of Wind Engineering and Industrial Aerodynamics

The state of the art of computational wind engineering is reviewed. Firstly, the numerical method for simulating turbulent airflow in wind engineering is described briefly. The diagnostic system for assessing the results of numerical simulation is described and error estimation and mesh resolution are discussed. Next the time-dependent flowfield is predicted by 3D Large Eddy Simulation and the results are illustrated using the techniques of animated graphics. Lastly an example of practical application is described using the flowfield prediction around an actual building complex.


On turbulent vortex shedding flow past 2D square cylinder predicted by CFD [J]

February 1995

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754 Reads

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213 Citations

Journal of Wind Engineering and Industrial Aerodynamics

Analyses by CFD on unsteady flow fields past a two-dimensional (2D) square cylinder are reviewed. The accuracy of the predicted results by CFD is examined from various view points. In the first part of the paper, the comparison of the results of large eddy simulation (LES) for 2D and 3D computations are described. The LES results given from 3D computation agree very well with the experimental results, but the results based on 2D computation are different from those based on 3D computation as well as from those given from experiments. The second part of the paper concerns detailed testing of 3D LES computations for the analysis of periodic and stochastic fluctuations, for which detailed experimental data are available. Results of LES computations are compared with those from turbulence models based on Reynolds-averaged Navier-Stokes equations (RANS models) as well as with those from experiments. Finally, results of 3D LES of unsteady pressure field and wind force acting on an oscillating square cylinder are presented.


Citations (44)


... These spaces include, but are not limited to, crowded places, such as stadiums, open markets, public transportation, school yards, and outdoor concert spaces, where social distancing can significantly influence heat transfer dynamics (Viswanathan et al., 2023;Ozeki et al., 2002). Therefore, understanding the convective heat transfer coefficient (h c ) is essential for developing thermal control and comfort models in such environments (Ichihara et al., 1997;Murakami et al., 2000). Moreover, the wind pressure and This preprint research paper has not been peer reviewed. ...

Reference:

Title: Convective Heat Transfer and Drag Coefficients of Human Body in Multiple Crowd Densities and Configurations in Semi-outdoor Scenarios
Combined simulation of airflow, radiation and moisture transport for heat release from human body
  • Citing Article
  • January 1998

... A coupled approach of convection, radiation, and conduction for the three-dimensional outdoor thermal environment was first initiated by Yoshida et al. based on a self-edited program [34]. They compared the results of simulations with field measurements from a northern part of Tokyo. ...

CFD prediction of thermal comfort in microscale wind climate
  • Citing Article
  • January 2000

... For each small surface, various factors were considered, including solar radiation, sky radiation, longwave radiation between the surface and other surfaces, convective heat transfer and latent heat transfer between the surface and ambient air, and conduction heat transfer through the surface. The shape factor was calculated by the Monte Carlo method [38,39] and the radiative heat transfer was calculated by Gebhart's absorption factor [40]. Due to the different absorptivity under shortwave and longwave radiation, the values of Gebhart's absorption factor were also different, so each surface was calculated separately. According to the former studies [34,41,42], and considering the above heat transfer, the urban surface temperature can be reproduced well. ...

Radiative heat transfer analysis method for coupled simulation of convection and radiation in large-scale and complicated enclosures. Part 1-Accurate radiative heat transfer analysis based on Monte Carlo method
  • Citing Article
  • January 2003

... The governing equations of RANS are solved based on the finite volume method 249 (FVM) with the application of the general-purpose CFD software package Fluent 250 2020R2. To examine the applicability of the inflow conditions for modeling twisted 251 wind profiles, the standard k-ε model (Jones and Launder, 1972), realizable k-ε model 252 (Shih et al., 1995), Renormalization Group k-ε model (RNG) (Yakhot and Orszag,253 1986), MMK model (Kondo et al. 1994(Kondo et al. , 1995 and Shear Stress Transport (SST) k-ω 254 model (Menter, 1997) ...

Numerical prediction of flow field around 2D square rib using revised k-ε model
  • Citing Article
  • January 1995

Journal of Wind Engineering

... In addition, this review paper focused only on journal papers which are prepared in English language but surely, valuable studies on CFD urban microclimate analysis have been published in the past as conference papers (e.g. [386][387][388]) or in other languages (e.g. [389,390]). ...

Software platform for the total analysis of wind climate and urban heat island-integration of CWE simulations from human scale to urban scale
  • Citing Article
  • January 2000

... It is common knowledge that trees can provide relief from high wind speeds [9]. Researchers in Ni- igata, Japan, have shown via extensive numerical analysis that planting trees near pedestrian walkways can reduce wind speeds to below 70% of what would otherwise be observed [10,11]. ...

Development of three dimensional plant canopy model for numerical simulation of outdoor thermal environment
  • Citing Article
  • January 2006

... The numerical results of v rms /v max have also an agreeable trend with the experimental data of Miyamoto and Okayama [28] at a Grashof number (Gr) of 4.84 × 10 10 . On the other hand, the peak of u rms /v max appears in the outer region and agrees well with Kato et al. [29] who used a Laser Doppler anemometer to measure the air velocity. Tsuji and Nagano [25] at Gr = 8.44 × 10 10 used a hot wire measurement technique for the velocity, which provides larger fluctuations in the buoyant sub-layer. ...

Experimental and numerical study on natural convection with strong density variation along a heated vertical plate
  • Citing Article
  • January 1993

... Several numerical and experimental studies on the traditional wall-return system showed that contaminant particle sizes smaller than 4.5 µm in diameter having no gravitational sedimentation effect on the diffusion [13][14][15]. Kato et al., [16]. Presented a technique for balancing the supply and exhaust airflow rates at the ceiling. ...

Numerical study on diffusion in a room with a locally balanced supply-exhaust airflow rate system
  • Citing Article
  • January 1992

ASHRAE Transactions

... Consequently, a total of 2,530 papers were collected (e.g. Murakami, 1987Murakami, ,1991 . Out of the papers collected, the following four categories of basic information were extracted: (1) title, (2) author name(s), (3) journal title, and (4) year of publication, and furthermore, the following seven items were extracted as analysis information: (5) room volume, (6) the number of cells, (7) turbulence model, (8) analysis code, (9) the scheme of convective term, (10) algorithms, and (11) boundary condition. ...

Three-dimensional numerical simulation of turbulent airflow in a ventilated room by means of a two-equation model
  • Citing Article
  • January 1987

ASHRAE Transactions

... Subsequent numerical studies confirmed the superiority 67 of TcAF through the analysis of the spatial bacterial-carrying-particles (BCPs) concentration 68 [11,12]. The existing literature suggests that TcAF can serve as an alternative to traditional and visitation frequency [14][15][16][17][18][19][20][21][22][23]. These metrics serve to evaluate two main aspects of 81 ventilation: air replacement and contaminant removal. ...

New ventilation efficiency scales based on spatial distribution of contaminant concentration aided by numerical simulation
  • Citing Article
  • January 1988

ASHRAE Transactions