The Effects of Forest Canopy Models on Damping of Turbulent Energy in a Flow

森林冠层模型对流动中湍流能量阻尼的影响

基本信息

批准号：
09650200
负责人：
HIRANO Kimitaka
金额：
$ 1.98万
依托单位：
Miyazaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650200/
关键词：
plant canopy wind tunnel testing finite difference method turbulent energy leaf area index effect of wind break 植生流体力学森林キャノピ-エネルギー減衰乱れ環境流体力学

项目摘要

This research is composed of three parts ; (1) the first is the experiments with the medium wind tunnel, (2) the second is that with the large wind tunnel, and (3) the third is the numerical simulation with the finite difference method and the crown-particle dynamics like the molecular dynamics.(1) The canopy model in this testing has the leaf area index of 6.6. Distributions of streamwise velocity components in the downstream region of the model are measured with the CTA.Flows between individual tree models are different from flows downstream of trees. Flows downstream of the canopy models showed strong three-dimensional characteristics.(2) This testing is experimented with the large wind tunnel constructed in Miyazaki University on January 1998. The canopy model has the leaf area index of 9.0. Distributions of the time-averaged velocity and intensity of turbulence in the shear-layer above the canopy are changed with the different pitch from arrangement of individual tree models.(3) Flow fields are simulated with the FDM-SMAC method. The crowns of canopy are approximated with a lot of particles that are connected with neighbor particles by spring and damper. The motion of air flows and the motion of particles in the crown are linked in the time-marching. Flow fields around the canopies of various sparse and dense crowns are calculated numerically. These results are good agreement with the results of the experiments with the wind tunnel testing.

本研究由三部分组成；（1）第一个是中型风洞实验，（2）第二个是大型风洞实验，（3）第三个是有限差分法和冠粒子动力学的数值模拟，如(1)本次测试的冠层模型叶面积指数为6.6。模型下游区域的流向速度分量的分布是用 CTA 测量的。各个树木模型之间的流动与树木下游的流动不同。冠层模型下游流动表现出较强的三维特征。(2)本次试验是在1998年1月宫崎大学建造的大型风洞中进行的。冠层模型的叶面积指数为9.0。树冠上方剪切层湍流的时均速度和强度分布随单树模型排列间距的不同而变化。(3)采用FDM-SMAC方法对流场进行了模拟。冠层近似有许多粒子，这些粒子通过弹簧和阻尼器与相邻粒子连接。空气流动的运动和冠部颗粒的运动在时间行进中是相互关联的。对各种稀疏和密集树冠冠层周围的流场进行了数值计算。这些结果与风洞测试的实验结果非常吻合。