S. de Miranda

Effects of Low Incoming Turbulence on the Flow around a 5 : 1 Rectangular Cylinder at Non-Null-Attack Angle

The incompressible high Reynolds number flow around the rectangular cylinder with aspect ratio 5 : 1 has been extensively studied in the recent literature and became a standard benchmark in the field of bluff bodies aerodynamics. The majority of the proposed contributions focus on the simulation of the flow when a smooth inlet condition is adopted. Nevertheless, even when nominally smooth conditions are reproduced in wind tunnel tests, a low turbulence intensity is present together with environmental disturbances and model imperfections. Additionally, many turbulence models are known to be excessively dissipative in laminar-to-turbulent transition zones, generally leading to overestimation of the reattachment length. In this paper, Large Eddy Simulations are performed on a 5 : 1 rectangular cylinder at non-null-attack angle aiming at studying the sensitivity of such flow to a low level of incoming disturbances and compare the performance of standard Smagorinsky-Lilly and Kinetic Energy Transport turbulence models.

A family of virtual element methods for plane elasticity problems based on the Hellinger–Reissner principle

Abstract In the framework of 2D elasticity problems, a family of Virtual Element schemes based on the Hellinger–Reissner variational principle is presented. A convergence and stability analysis is rigorously developed. Numerical tests confirming the theoretical predictions are performed.

Large Eddy Simulation of Turbulent Flows: Benchmarking on a Rectangular Prism

Preliminary results of a Large Eddy Simulation (LES) of rectangular cylinder performed with OpenFoam are presented. This is the preliminary part of a longer research project aimed at systematically study the ability of Computational Fluid Dynamics (CFD) techniques in reproducing the flow around slender bodies with sharp edges at high Reynolds numbers. In spite of the simple geometry, the problem is influenced by a number of parameters which makes its correct solution difficult to be achieved. The LES approach presented here appears to be a good candidate for this purpose but further analysis must be performed. Indeed, we highlight the need to adopt a finer resolution in the spanwise direction in order to capture the very anisotropic turbulent dynamics. Furthermore, it emerges the need of Direct Numerical Simulation (DNS) data in order to shed light on the compound role played by the turbulence model, the grid resolution and the inlet conditions.

A simple beam model to analyse the durability of adhesively bonded tile floorings in presence of shrinkage

A simple beam model for the evaluation of tile debonding due to substrate shrinkage is presented. The tile-adhesive-substrate package is modeled as an Euler-Bernoulli beam laying on a two-layer elastic foundation. An effective discrete model for inter-tile grouting is introduced with the aim of modelling workmanship defects due to partial filled groutings. The model is validated using the results of a 2D FE model. Different defect configurations and adhesive typologies are analysed, focusing the attention on the prediction of normal stresses in the adhesive layer under the assumption of Mode I failure of the adhesive.

A numerical framework for simulating fluid-structure interaction phenomena

In this paper, a numerical tool able to solve fluid-structure interaction problems is proposed. The lattice Boltzmann method is used to compute fluid dynamics, while the corotational finite element formulation together with the Time Discontinuous Galerkin method are adopted to predict structure dynamics. The Immersed Boundary method is used to account for the presence of an immersed solid in the lattice fluid background and to handle fluid-structure interface conditions, while a Volume-of-Fluid-based method is adopted to take trace of the evolution of the free surface. These ingredients are combined through a partitioned staggered explicit strategy, according to an efficient and accurate algorithm recently developed by the authors. The effectiveness of the proposed methodology is tested against two different cases. The former investigates the dam break phenomenon, involving the modeling of the free surface. The latter involves the vibration regime experienced by two highly deformable flapping flags obstructing a flow. A wide numerical campaign is carried out by computing the error in terms of interface energy artificially introduced at the fluid-solid interface. Moreover, the structure behavior is dissected by simulating scenarios characterized by different values of the Reynolds number. Present findings are compared to literature results, showing a very close agreement.