浅水流动有限体积法/Osher格式的二维水流-水质模拟

应用无结构网格有限体积法 /Osher格式的二维水流 -水质耦合数值模型 ,采用黎曼近似解计算模拟区域水量、动量及污染物输送通量。通过对长江南京八卦洲江段浓度场的模拟计算 ,其结果与遥感卫星图片确定的污染带分布相吻合 ,证实了模型的合理性和模拟能力     

天灾成因的一种新认识

自然灾害的发生不是独立的,它们是相互联系的。本文在总结过去几十年研究成果的基础上,从地气耦合的观点出发,对自然灾害的成因提出了一种看法。     

龙卷风风灾的调查与评估

以江苏省为例搜集并核实了最近３７年间龙卷风的事实和灾情资料，尝试性地采用专家评分方式从风灾实况对各次龙卷风的强度进行了富士达级别评定，论证了这种从具有模糊性的灾情事实中提取半定量信息方法的客观性。结果发现，各强度级别是龙卷风的累积分布可近似用两段指数函数拟合。在此基础上，定量地给出了江苏省龙卷风频率和强度的地域分布，各级龙卷风的平均再现间隔年数等统计指标。     

影响平板式太阳能热水器热效率诸因素的研究

本文根据辐射传热和对流传热理论,利用Ｍａｔｌａｂ 程序结合太阳能热水器本身的尺寸以及与其有关的水和空气的物理弹性详细分析了影响平板式太阳能热水器热效率的因素包括太阳能热水器表面的太阳光辐射的吸收率αｓ 和辐射系数ε,太阳能热水器的水进口温度Ｔｃ,ｉｎ和流量ｍｃ 太阳辐射能力Ｇｓ,,环境大气温度Ｔｅ,大气辐射系数εｓｋｙ 以及太阳能热水器内部的总传热系数Ｕ。分析结果表明较高的太阳照射能力、环境温度和总传热系数有利于提高集热效率,而增加水量和水进口温度、热水器辐射系数和大气辐射系数则有相反的效果。     

流体流动状态对超滤效率及膜污染的影响

超滤技术作为膜分离技术的一种,由于具有效率高、能耗低等优点已经被多种行业广泛应用.但是,浓差极化和膜污染却极大降低膜分离效率,成为制约膜分离技术推广应用的重要因素.解决和减轻浓差极化和膜污染的方法有很多,本文着重于流体流动状态对浓差极化和膜污染的影响进行了论述.     

面向节能减排的通信基站通风冷却系统研究

作为高能耗行业,通信行业中通信基站的散热能耗量就一直居高不下,如何降低其能耗是目前各运营商迫切期待解决的问题。针对这一问题,根据烟囱效应增强对流散热的原理,提出了一种"烟囱"通风与空调降温相结合的通风冷却系统设计方案,然后通过三维热-流体耦合计算分析了影响此结构散热的关键因素,在此基础上采用正交实验对基站散热结构的参数进行了优化,最大化降低基站运行的温度,从而达到了减少通信基站运行成本的目标。     

Parameterization of the roughness length over the sea in forced and free convection

In the condition of free convection, the Charnock relation is inadequate. In this paper we extend the Charnock relation to include the effect of free convection on the roughness length. As a result, the singularity in the Monin–Obukhov similarity theory can be avoided. This paper shows two approaches to derive the roughness length formula in the forced and free convections. The first approach is based on the mixing length theory and the use of the observational data of the vertical velocity variance. We introduce a new vertical velocity scale based on the vertical velocity variance; this velocity variance is well behaved in the atmospheric boundary layer and easy to obtain from field experiments. The second approach is based on the theoretical framework of Sykes et al. (Q R Met Soc, 119: 409–421). From that framework, we develop a theory to obtain the roughness length formula. The results of these two approaches are in agreement with each other. In the past, a multiplication factor associated with free convection was considered to be a constant. This paper shows that this multiplication factor is, in fact, also dependent on the depth of the mixing height. In previous studies, experimental works were often conducted without taking into account the depth of the mixing height. Not taking into account the mixing height in the estimation of the roughness length in free convection would result in an inaccurate estimate of the roughness length and hence the drag coefficient. An erratum to this article can be found at