建筑墙体材料湿扩散率的测量

建筑墙体材料的湿扩散率表示水蒸气在该材料中的迁移能力,是研究墙体材料湿迁移所必需但相当匮乏的重要参数。在比较分析国内外有关湿迁移试验研究的基础上,设计了利用脉冲电导法获取建筑材料等温湿扩散率的试验方案,并对南京市普遍使用的多孔砖的湿扩散率进行了测试。

基于有限差分法模拟木材吸湿性的研究

为研究木材在不同相对湿度下吸湿过程含水率的变化，建立木材吸湿的动力学模型。用有限元差分方格法离散化方程，参照试验测得的浓度依赖性的扩散率和表面扩散系数，并利用matlab计算机软件进行求解。进行的两组试验不仅计算模型中的参数（结合水的扩散率、木材表面的吸湿系数），还对模型进行验证。吸湿试验分两部分研究，一是在木材的纵向上，将木材现在50％的相对湿度中达到平衡，再一步步提高相对湿度（50～58％，58～66％，66～74％，74～82％）；二是分别提高相对湿度（50～58％，50～66％，50～74％，50～82％）做平行试验，测木材的吸湿量。结果显示试验测得的吸湿量和模型模拟出的结果具有很好的相关性，证明吸湿模型的可行性。

Liquid spreading on a pre-wetted biomimetic surface inspired by a dog's tongue

Liquid film flow widely exists in industries due to its high thermal film is strongly influenced by the properties of the working surface efficiency and low flow flux. The spreading of the liquid A biomimetic surface with multi-scale structures inspired by the skin of a dog＇s tongue is proposed in this paper for the enhancement of heat and mass transfer. The spreading and flow behaviors of a gravity-driven liquid falling down the pre-wetted biomimetic surface are compared with that on the smooth sur- faces, via the combination of numerical simulations using the volume of fluid （VOF） method, and experimental measurements using high-speed imaging. On the pre-wetted smooth substrate, liquid merges with two droplets before the free surface of the liquid slowly develops into a parabolic shape. In contrast, on the biomimetic surface, liquid rapidly and uniformly spreads into a thin film which could effectively enhance mass transfer in both spanwise and streamwise directions. The characteristics and distribution of the microstructures on the proposed biomimetic surface are potentially to be used to guide the design of the surface in high efficiency heat exchangers and reactors.