Computational Fluid Dynamics simulations of wind-driven rain on a low-rise building : new validation efforts

Despite the establishment of CFD as a tool for calculating the amount of wind-driven rain (WDR) falling onto building facades, very few efforts have been made towards the validation of CFD for this purpose. This paper presents part of a detailed CFD validation study that was conducted at the Laboratory of Building Physics, supported by a new experimental wind, rain and WDR database for a low-rise building. It will be shown that numerical simulation, if conducted with care, can provide quite accurate predictions of the amount of WDR impinging on the building facade and that the main discrepancies in this case were due to a simplification of the upstream wind conditions in the numerical model

A Continuous-Discontinuous Approach to Simulate Heat Transfer in Fractured Media

A macroscopic framework to model heat transfer in materials and composites, subjected to physical degradation, is proposed. The framework employs the partition of unity concept and captures the change from conduction-dominated transfer in the initial continuum state to convection and radiation-dominated transfer in the damaged state. The underlying model can be directly linked to a mechanical cohesive zone model, governing the initiation and subsequent growth and coalescence of micro-cracks. The methodology proved to be applicable for quasi-static, periodic, and transient problem

Hygroscopic behaviour of paper and books

This study presents experimental analysis and numerical modeling of hygroscopic moisture buffering by paper and books. First, a literature review of moisture transport properties of paper is presented. Experimental work on two paper types includes SEM analysis of the paper structure, determination of sorption isotherms and water vapor permeability measurements. A hysteretic model for paper is presented, which is based on the measurement of the main adsorption and desorption curves. It is shown that the water vapor permeability in a hysteretic model is dependent on the moisture content and not on the relative humidity. Books consist of several paper sheets with air layers between the sheets. To take the air layers into account, a parallel transport model is proposed to determine the effective moisture transport properties of books taking into account the air layers. The dynamic hygroscopic behavior of small book samples was measured. It is shown that, although the water vapor permeability of different paper types can be quite different, the effusivity of a book highly depends on the presence of the air layers and can therefore remain comparable for different paper type

New horizons in computer analysis of damage and fracture in quasi-brittle materials

Continuum approaches are reviewed which can properly model localised deformations that act as a precursor to final fracture in quasi-brittle materials. Next, one such higher-order damaging continuum model is combined with a stochastic approach to describe the heterogeneity in quasi-brittle materials

New horizons in computer analysis of damage and fracture in quasi-brittle materials

Continuum approaches are reviewed which can properly model localised deformations that act as a precursor to final fracture in quasi-brittle materials. Next, one such higher-order damaging continuum model is combined with a stochastic approach to describe the heterogeneity in quasi-brittle materials

Some future directions in computational failure mechanics

Continuum approaches are reviewed which can properly model localised deformations that act as a precursor to final fracture in quasi-brittle materials. Next, one such higher-order damaging continuum model is combined with a stochastic approach to describe the heterogeneity in quasi-brittle materials

Intercomparison of wind-driven rain models based on a case study with full-scale measurements

Three different calculation models for wind-driven rain (WDR) are compared: the semi-empirical model in the ISO standard for WDR (ISO), the semi-empirical model by Straube and Burnett (SB) and the CFD model by Choi, extended by Blocken and Carmeliet. This paper builds further on the comparison of these models for idealized building configurations and fixed wind and rain conditions in [Blocken et al., 2010. Comparison of calculation models for winddriven rain deposition on building facades, Atmospheric Environment 44(14): 1714-1725]. In the present paper, these models are applied to a high-rise monumental tower building, for a transient rain event, and the model results are compared with full-scale measurements. The agreement between the CFD results and the measurements is quite good at the upper part of the facade, while the ISO and SB model show large discrepancies at these facade positions

VE-cadherin and claudin-5: it takes two to tango

Endothelial barrier function requires the adhesive activity of VE-cadherin and claudin-5, which are key components of adherens and tight endothelial junctions, respectively. Emerging evidence suggests that VE-cadherin controls claudin-5 expression by preventing the nuclear accumulation of FoxO1 and -catenin, which repress the claudin-5 promoter. This indicates that a crosstalk mechanism operates between these junctional structures