大气对舰载激光武器的影响及对策

强激光的大气传输效应是影响和制约舰载激光武器性能的重要因素,包括大气折射、吸收、散射、湍流、热晕和击穿,使激光发生路径弯曲、功率衰减、光强起伏、光束扩展和畸变等。从舰载激光武器的作战环境和作战特点出发,结合目前舰载激光武器的最新进展和发展趋势,综合分析了海上大气对舰载激光武器作战效能的影响,并提出了减小大气传输影响的应对措施,有助于舰载激光武器系统的合理设计和性能的最大发挥。     

2016年冬季寿县一次边界层低空急流对污染物扩散的影响

利用安徽寿县地区2016年12月16~17日的观测资料与模拟资料,分析了一次夜间边界层低空急流对PM_2.5扩散的影响.此过程中,急流分布范围广,强度大,最大风速可达10~12m/s,而且风向随高度有明显转向,高低层风向差可达90°.急流发展过程中,急流轴基本位于200m以下,急流的最小风速高度出现在400~800m之间.通过分析可知,对于不同高度,急流对污染物扩散的影响存在明显差异.地面至急流轴范围内,PM_2.5总体减少.急流的出现使湍流混合明显增强,在湍流作用下污染物向上混合,使该层PM_2.5显著减少,净质量通量的峰值可达-103×10^-3μg/(m²·s).急流的水平输送可带来上风方较为清洁气团,同样减少了该层的PM_2.5浓度.但与湍流作用相比其影响较小,净质量通量仅为-2.9×10^-3μg/(m²·s).急流存在时,还会加强向下的垂直风速,在垂直输送作用下,上层污染物向下输送,增加了该层PM_2.5浓度,净质量通量约为11×10^-3μg/(m²·s).急流轴至风向转变高度之间,PM_2.5总体增加.这是由于湍流作用将低层高浓度污染物输送至该层,使PM_2.5浓度增加,净质量通量约为23.9×10^-3μg/(m²·s);水平输送作用使该层PM_2.5浓度略有增加,净质量通量约为2.3×10^-3μg/(m²·s);而垂直输送作用带来了高处较为清洁的气团,减少了PM_2.5浓度,净质量通量约为-6.6×10^-3μg/(m²·s).风向转变高度至LLJ最小风速高度之间,PM_2.5总体增加.湍流作用仍占主导,净质量通量约为17.8×10^-3μg/(m²·s);垂直输送作用稍有贡献,净质量通量约为1.4×10^-3μg/(m²·s);而水平输送起减少作用,净质量通量约为-3.7×10^-3μg/(m²·s).     

可爆性气体泄漏扩散时均湍流场的数值模拟

本介绍了一种基于κ—ε湍流模型的研究可爆性气体泄漏扩散的三维数值模拟方法。中对乙炔气体扩散试验的风场和质量浓度场进行了数值模拟，并将质量浓度场的数值模拟结果与风洞试验数据进行了比较。模拟结果与试验数据吻合得很好，从而验证了本数值模拟方法的有效性。     

紊动水体复氧规律研究

根据紊动扩散理论及气液界面质量传递过程，在对流场精确描述和对表面传质系数充分研究的基础上，建立了三维紊动水体复氧模型。模型充分考虑了流场及紊动特性对复氧影响。     

A three-dimensional prediction system for water qualitypolluction in coastal waters

ＩｎｔｒｏｄｕｃｔｉｏｎＨａｋａｔａＢａｙｉｓａｓｅｍｉ ｅｎｃｌｏｓｅｄｂａｙ(ｆｒｏｍ 33°34′Ｎｔｏ 33°41′Ｎａｎｄｆｒｏｍ 1 30°1 3′Ｅｔｏ 1 30°2 6′Ｅ)ｌｏｃａｔｅｄａｔｔｈｅｎｏｒｔｈｓｉｄｅｏｆＫｙｕｓｈｕＩｓｌａｎｄ ,Ｊａｐａｎ .ＴｈｅｌｅｎｇｔｈａｎｄｗｉｄｔｈｏｆＨａｋａｔａＢａｙｉｓａｂｏｕｔ2 0ｋｍａｎｄ 1 0ｋｍｒｅｓｐｅｃｔｉｖｅｌｙ .Ｔｈｅｓｕｒｆａｃｅａｒｅａｉｓａｂｏｕｔ 1 33ｋｍ2 ａｎｄｔｈｅｍｅａｎｗａｔｅｒｄｅｐｔｈｉｓａｂｏｕｔ1 0 .5ｍ .Ｔｈｅｂａｙｍｏｕｔ…     

沿岸熏烟扩散的中尺度模拟系统

建立了一个沿岸熏扩散的中尺度模拟系统，它由一个二维二阶矩闭合的ＰＢＬ模式和一个随机流动扩散模式组成。初步的模拟和一些数值试验结果表明，随机游动扩散模式与现行的基于高斯扩散公式的熏烟扩散模式比较，其物理模型更为合理；采用二阶矩湍流闭合方案的ＰＢＬ模式能模拟得到合理的热力内边界层（ＴＩＢＬ）结构特征，将二阶矩湍流闭合ＰＢＬ模式模拟所得气象场作为随机游动扩散模式的气象输入，可以较好地预测沿岸地区日间持续     

Turbulence closure models and their application in RAMS

Turbulence closures are fundamental for modelling the atmospheric diffusion in numerical codes and the resulting eddy diffusivities are key parameters in describing the transport and dispersion in the boundary layer. In this work, four turbulence closure schemes have been applied for reproducing a neutral flow over schematic complex terrain using the meteorological model RAMS. Two of the closures, a one-equation (E-l) and a two-equations (E-) model, have been implemented in RAMS in alternative to the ones originally available. In these cases, an analytical method based on the similarity theory for the atmospheric surface layer and boundary layer is adopted to calculate the empirical constants of the turbulence closures. Some examples of numerical studies performed to simulate the flow and turbulence over a 3-D hill in wind-tunnel experiment in neutral stratification are presented and discussed. An intercomparison of simulations related to different closures is considered by analysing the main features of the flow over the hill and by comparing calculated vertical profiles of turbulent kinetic energy with measured ones.     

The Modelling of Turbulence from Traffic in Urban Dispersion Models — Part II: Evaluation Against Laboratory and Full-Scale Concentration Measurements in Street Canyons

The paper addresses the problem of the parameterisation of traffic induced turbulent motion in urban dispersion models. Results from a variety of full-scale and wind-tunnel studies are analysed and interpreted within a modelling framework based on scaling considerations. The combined effects of traffic and wind induced dispersive motions are quantified for different traffic situations (variable traffic densities, vehicle velocities and vehicle types) and incorporated into the developed parameterisations. A new dispersive velocity scale is formulated and recommendations regarding its application in urban dispersion models are given. The necessity of accounting for traffic induced air motions in predictions of street-canyon pollution levels is demonstrated. Further research is needed to verify the empirical constants in the proposed parameterisations and to generalize the developed approach for a broader range of urban building configurations, meteorological conditions, and traffic situations.     

Turbulence-Based Models for Gas Transfer Analysis with Channel Shape Factor Influence

Gas transfer through surface water of streams is an effective process for the environmental quality of the aquatic ecosystem. Several theoretical approaches have been proposed to estimate gas transfer rate. This paper is devoted to present a turbulence-based model and to compare it with other 3 turbulence-based modeling frameworks that provide an estimation of gas-transfer coefficient K_L at the air-water interface. These models were derived for the reaeration process. In this paper, they have been verified both for reaeration and volatilization using experimental data collected in a laboratory rectangular flume and in a circular sewer reach. These data refer to oxygen absorption and cyclohexane volatilization, respectively. Comparison of results for oxygen shows that the tested models exhibit an average absolute difference between their results and the experimental data ranging from 12.5% and 25.6%. Also, the scaling analysis of the experimental data support both small-eddy based models and the model proposed by the authors. Moreover, volatilization results show that the process is also affected by a channel shape factor, which was, finally, quantified.