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Povzetek: Multiphase flows are of great relevance to a wide range of industries, and their simulation using Computational Fluid Dynamics (CFD) is an important pillar for conducting design studies and gaining physical insight. However, a particular challenge in the simulation of multiphase flows is the occurrence of different morphologies or flow regimes, i.e. dispersed vs. segregated. The established simulation frameworks that have been developed over the years are usually only applicable to a specific morphology and level of detail. The simulation of a combination of morphologies is particularly challenging, and adaptive approaches are sought where the trade-off between level of detail and time to solution is mainly a matter of spatial resolution, rather than the fundamental choice of a method. In this respect, the Euler-Euler model has crucial properties that make it a good basis. This paper gives an overview of existing morphology-adaptive Eulerian methods, also often referred to as hybrid Eulerian methods. It is the result of a joint effort of the Dresden6 initiative, a loose association of research groups already active in this field. It gives an honest picture of current shortcomings and future development prospects. The aim of the work is to start a homogenization process by establishing a common terminology and listing suitable test cases that can be used for benchmarking, i.e. verification and validation.
Ključne besede: numerical simulations, multiphase flows, morphology-adaptive method, separated effect tests, integral tests
Objavljeno v DiRROS: 29.04.2026; Ogledov: 287; Prenosov: 180
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Povzetek: In order to calculate amount of interstitial condensation in a building envelope, water vapour resistance of each layer is of importance. Once having it, 1D calculation according to ISO 13788 with monthly average vapour pressures can be applied. In EN 14509 sandwich panels are considered to be impermeable for water vapour, thus (according to the standard) water vapour cannot enter from outside and condensate in the panels. But it is not always true for real sandwich panels, because joints between neighbouring panels can cause non-neglecting water vapour bridges. Although in measurements of linear water vapour transmittance of the joints (Ψv) stationary boundary vapour pressures can be applied, the measurements can be long lasting. We shortened time needed to get Ψv performing simulations in Delphin6.0. We simulated panels and steel sheets with joints using constant boundary vapour pressures and compared the results with the results of measurements on the equivalent systems. In systems under consideration a sealant in built-in-state, located at a joint of a sandwich panel, is a compressed EPDM tube. It is impossible to directly measure its effective μ according to ISO 12572. In the paper we study to which precision it is possible to determine it using measurements and simulations. Once having effective μ of the sealant (if all other necessary material parameters available) one can simulate condensation in envelopes including sandwich panels in 2D according to EN 15026 using hourly climatic data. Another goal of the study was determination of differences in resulting Ψv values when varying narrowest part of the gap dGAP at the joint in the panels without any sealant. Results confirm significant sensibility of Ψv to variations of dGAP.
Ključne besede: water vapour condensation, water vapour diffusion, numerical simulations, water vapour resistance, linear water vapour transmittance, sendwich panels
Objavljeno v DiRROS: 05.03.2024; Ogledov: 1603; Prenosov: 1118
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