In this paper we propose a Finite Element model for analyzing closed membranes (“bags”) interacting with internal and external (surrounding) fluids. The approach is based on embedding a Lagrangian monolithic model describing the membrane containing an internal fluid into an Eulerian external fluid model. The combination of kinematic frameworks allows us to accurately track the location of the membrane and naturally represent flow variables discontinuities across it. In order to obtain stable coupling for membrane materials with low density, a slight fluid compressibility is assumed. The coupling between the membrane and the internal fluid is automatically accounted for by a monolithic set-up. The filled membrane and the external fluid are coupled in a Dirichlet–Neumann fashion. The model is validated in several numerical examples and its potential application to a civil engineering problem of coast protection via water-filled bag reefs is shown.
Abstract
In this paper we propose a Finite Element model for analyzing closed membranes (“bags”) interacting with internal and external (surrounding) fluids. The approach is based [...]
An embedded Eulerian-Lagrangian formulation for the simulation of droplet dynamics within a polymer electrolyte fuel cell (PEFC) channel is presented. Air is modeled using an Eulerian formulation, whereas water is described with a Lagrangian framework. Using this framework, the gas-liquid interface can be accurately identified. The surface tension force is computed using the curvature defined by the boundary of the Lagrangian mesh. The method naturally accounts for material property changes across the interface and accurately represents the pressure discontinuity. A sessile drop in a horizontal surface, a sessile drop in an inclined plane and droplets in a PEFC channel are solved for as numerical examples and compared to experimental data. Numerical results are in excellent agreement with experimental data. Numerical results are also compared to results obtained with the semi-analytical model previously developed by the authors in order to discuss the limitations of the semi-analytical approach.
Abstract
An embedded Eulerian-Lagrangian formulation for the simulation of droplet dynamics within a polymer electrolyte fuel cell (PEFC) channel is presented. Air is modeled using an Eulerian formulation, whereas water is described with a Lagrangian framework. Using this framework, the [...]
For years there has been a need to develop multifunctional composite materials, which in addition to the classical properties such as high strength and high stiffness, integrate different functionalities such as the ability to detect any deformation of the structure or the integration of lighting, in a trend towards lighter structures.
However, in most cases, embedding physical components can lead to negative aspects in the structures such as the presence of discontinuities in the resin that are prone to delamination or the initiation of cracks around the component, decreasing its structural properties.
Fabrication techniques, based on functional printing for the development of printed circuits and electronics as an inherent part of the structure, are very promising and are therefore gaining market acceptance.
This work shows the analysis of the mechanical properties of continuous fibre composites with printed electronics on different fabrics used in the manufacturing processes themselves, such as glass fibres or on polymeric veils manufactured by the electrospinning technique. The results obtained show that there are no relevant differences in tensile behaviour due to the fact of having printed circuits and even with different line thicknesses. Likewise, the elasticity module is not affected in the case of composites that embed lighting circuits based on LEDs integrated on the veil.
The printed lines on the different substrates have also been analysed by microscopy and the behaviour of a resistive temperature sensor printed on the veil and embedded in composite has been measured, for which a linear response with a sensitivity of 4.9Ω/ºC has been achieved.
Abstract
For years there has been a need to develop multifunctional composite materials, which in addition to the classical properties such as high strength and high stiffness, integrate different functionalities such as the ability to detect any deformation [...]
A finite element model for fluid–structure interaction problems involving closed membranes, internal and external fluids 