Preprint Article Version 1 This version is not peer-reviewed

Reproduction of Local Strong Wind Area Induced in the Downstream of Small‐scale Terrain by Computational Fluid Dynamic (CFD) Approach

Version 1 : Received: 2 April 2019 / Approved: 3 April 2019 / Online: 3 April 2019 (10:39:54 CEST)

How to cite: Uchida, T.; Araki, K. Reproduction of Local Strong Wind Area Induced in the Downstream of Small‐scale Terrain by Computational Fluid Dynamic (CFD) Approach. Preprints 2019, 2019040041 (doi: 10.20944/preprints201904.0041.v1). Uchida, T.; Araki, K. Reproduction of Local Strong Wind Area Induced in the Downstream of Small‐scale Terrain by Computational Fluid Dynamic (CFD) Approach. Preprints 2019, 2019040041 (doi: 10.20944/preprints201904.0041.v1).

Abstract

In this research, the computational fluid dynamic (CFD) approach that has been used in wind power generation field was applied for the solution of the problems of local strong wind areas in railway fields, and the mechanism of wind generation was discussed. At the same time, the affectivity of the application of computational fluid dynamic approach to railway field was discussed. The problem of local wind that occurs on the railway line in winter was taken up in this research. A computational simulation for the prediction of wind conditions by LES was implemented and it was clarified that the local strong wind area is mainly caused by separated flows originating from the small‐scale terrain positioned at its upstream (at approximately 180.0 m above sea level). Meanwhile, the effects of the size of calculation area and spatial grid resolution on the result of calculation and the effect of atmospheric stability were also discussed. It was clarified that when the air flow characteristic of the separated flow originating from the small‐scale terrain (at altitude of approximately 180.0 m) targeted in this research is reproduced at high accuracy by computational simulation of wind conditions, approximately 10.0 m of spatial resolution of computational grid in horizontal direction is required. As a result of the computational simulation of wind conditions of stably stratified flow (Fr = 1.0), lee waves were excited at the downstream of the terrain over time. As a result, the reverse‐flow region lying behind the terrain that had been observed at a neutral time was inhibited. Consequently, local strong wind area was generated at the downstream of the terrain and the strong wind area passing through the observation mast was observed. By investigating the speed increasing rate of local strong wind area induced at the time of stable stratification, it was found that the wind was approximately 1.2 times stronger than what was generated at a neutral time.

Subject Areas

Terrain‐induced severe wind event; Stratified flows; Computational Fluid Dynamics (CFD); LES

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