Static and dynamic thermal characterization of facade with mineral foam insulation using a hot-box apparatus

Reducing heat loss through the envelope of the building had been an efficient way to save on heating and reduce energy consumption of buildings. In Europe, typical exterior walls need to prevent heat loss during cold weather but more and more allow comfortable temperature condition during the hot season. Indoor comfort in hot seasons is dependent on the thermal transmittance and on its dynamic response during hot days. The study presents guarded hot-box measurements of exterior walls build with insulating masonry and insulation boards made of innovative mineral foam used as an insulation material. The masonry is a composite system of concrete block filled with mineral foam to reduce the thermal transmittance. Insulation boards are made of mineral foam and are added to achieve the overall thermal transmittance targeted. Static and dynamic measurements were performed in order to compare thermal transmittance and decrement delay. The results are compared with those obtained from calculations carried out of the same walls through the application of European standards and a finite volume simulation. Uncertainties of the guarded hot-box measurement and calculation methods are discussed. Results shows that with equivalent U-values, the solution offer higher decrement delay compared to a traditional wall using conventional masonry and polystyrene insulation boards.

Unsteady Hemodynamics in Intracranial Aneurysms With Varying Dome Orientations

Fluid loading within an intracranial aneurysm is difficult to measure but can be related to the shape of the flow passage. The outcome of excessive loading is a fatal hemorrhage, making it necessary for early diagnosis. However, arterial diseases are asymptomatic and clinical assessment is a challenge. A realistic approach to examining the severity of wall loading is from the morphology of the aneurysm itself. Accordingly, this study compares pulsatile flow (Reynolds number Re = 426, Womersley number Wo = 4.7) in three different intracranial aneurysm geometries. Specifically, the spatio-temporal movement of vortices is followed in high aspect ratio aneurysm models whose domes are inclined along with angles of 0, 45, and 90 deg relative to the plane of the parent artery. The study is based on finite volume simulation of unsteady three-dimensional flow while a limited set of particle image velocimetry experiments have been carried out. Within a pulsatile cycle, an increase in inclination (0–90 deg) is seen to shift the point of impingement from the distal end toward the aneurysmal apex. This change in flow pattern strengthens helicity, drifts vortex cores, enhances spatial displacement of the vortex, and generates skewed Dean's vortices on transverse planes. Patches of wall shear stress and wall pressure shift spatially from the distal end in models of low inclination (0–45 deg) and circumscribe the aneurysmal wall for an inclination angle of 90 deg. Accordingly, it is concluded that high angles of inclination increase rupture risks while lower inclinations are comparatively safe.