Development of a new k–ε model to reproduce the aerodynamic effects of snow particles on a flow field

Abstract This study aims to develop a new k–e model that incorporates the effects of snow particles on a flow field. In the first part of this paper, the results of wind-tunnel measurements of a flow over a loose-snow surface are presented. The spatial distributions of the mass flux of drifting snow, wind velocity, and turbulence were simultaneously measured under several different wind-speed conditions. The wind-tunnel data clearly show that wind velocity near the snow surface decreased because of the snow particles. In the latter part of this paper, the basic equations of the k–e model are modified to include new terms to express the effect of snow particles as moving obstacles on a flow field based on the concept of canopy-flow modeling. The model parameters included in the new terms, namely, R p [which is a model parameter related to the moving particle speed in terms of the wind velocity (0 R p C pe (which is a model coefficient included in the transport equation of energy dissipation rate), are optimized by comparing the wind-tunnel measurements and computational fluid dynamics predictions.

[1]  H. Hiraoka,et al.  Modelling of turbulent flows within plant/urban canopies , 1993 .

[2]  Anker Nielsen,et al.  Computer simulation of wind speed, wind pressure and snow accumulation around buildings (SNOW-SIM) , 1994 .

[3]  Said Elghobashi,et al.  On predicting particle-laden turbulent flows , 1994 .

[4]  Hiroshi Yoshino,et al.  Examining tree canopy models for CFD prediction of wind environment at pedestrian level , 2008 .

[5]  A. Mochida,et al.  Wind tunnel investigation of drifting snow development in a boundary layer , 2012 .

[6]  Y. Kaneda,et al.  Three-dimensional numerical simulation of snowdrift , 1991 .

[7]  Mohamed Naaim,et al.  Numerical simulation of drifting snow: erosion and deposition models , 1998 .

[8]  Yoshihide Tominaga,et al.  CFD modeling of snowdrift around a building: An overview of models and evaluation of a new approach , 2011 .

[9]  Thomas K. Thiis,et al.  A comparison of numerical simulations and full-scale measurements of snowdrifts around buildings , 2000 .

[10]  Takashi Maruyama.  Optimization of roughness parameters for staggered arrayed cubic blocks using experimental data , 1993 .

[11]  Tadashi Kimura,et al.  Field test of a new snow-particle counter (SPC) system , 1993 .

[12]  T. M. Harms,et al.  Outdoors modelling of snowdrift at SANAE IV Research Station, Antarctica , 2003 .

[13]  T. M. Harms,et al.  Numerical simulation of three-dimensional, transient snow drifting around a cube , 2004 .

[14]  Shuzo Murakami,et al.  Development of local area wind prediction system for selecting suitable site for windmill , 2003 .

[15]  J. C. R. Hunt,et al.  Saltation and incipient suspension above a flat particle bed below a turbulent boundary layer , 2000, Journal of Fluid Mechanics.

[16]  Yoshihide Tominaga,et al.  PIV measurements of saltating snow particle velocity in a boundary layer developed in a wind tunnel , 2013, J. Vis..

[17]  Akashi Mochida,et al.  Prediction of wind environment and thermal comfort at pedestrian level in urban area , 2006 .

[18]  K. Fujita,et al.  Snow particle speeds in drifting snow , 2014 .