Modelling the source of glacial earthquakes for a better understanding of the impact of iceberg capsize on glacier stability

2020 ◽  
Author(s):  
Pauline Bonnet ◽  
Vladislav Yastrebov ◽  
Alban Leroyer ◽  
Patrick Queutey ◽  
Anne Mangeney ◽  
...  
Keyword(s):  
Mass Loss ◽  
Fluid Structure Interaction ◽  
Greenland Ice Sheet ◽  
Stick Slip ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dynamic Mass ◽  
Glacier Terminus ◽  
Glacier Dynamics ◽  
The Impact

<p>One current concern in climate science is the estimations of the amount of ice loss by glaciers each year and the corresponding rate of sea level rise. Greenland ice sheet contribution is significant with about 30% to the global ice mass losses. Ice loss in Greenland is distributed approximately equally between loss in land by surface melting and loss at the front of marine-terminating glaciers that is modulated by dynamic processes. Dynamic mass loss includes both submarine melting and iceberg calving. The processes that control ablation at tidewater glacier termini, glacier retreat and calving are complex, setting the limits to the estimation of dynamic mass loss and the relation to glacier dynamics. It involves interactions between bedrock – glaciers – icebergs – ice-mélange – water – atmosphere. Moreover, the capsize of cubic kilometer scale icebergs close to a glacier front can destabilize the glacier, generate tsunami waves, and induce mixing of the water column which can impact both the local fauna and flora.</p><p>We aim to improve the understanding of iceberg capsize using a mechanical modeling of iceberg rotation against the glacier terminus, constrained by the generated seismic waves that are recorded at teleseismic distances. To achieve this objective, we develop a fluid-structure interaction model for the capsizing iceberg. Full scale fluid-structure interaction models enable accurate simulation of complex fluid flows in presence of rigid or deformable solids and in presence of free surfaces. However, such models are computationally very expensive. Therefore, our strategy is to construct a simple solid dynamics model involving contact and friction, whose simplified interaction with water is governed by parametrized forces and moments. We fine tune these parametrized effects on an iceberg capsizing in contact with a glacier with the help of reference direct numerical simulations of fluid-structure interactions involving full resolution of Navier-Stokes equations. We assess the sensitivity of the glacier dynamics to the glacier-bedrock friction law and the conditions for triggering a stick-slip motion of the glacier due to iceberg capsize. The seismogenic sources of the capsizing iceberg in contact with a glacier simulated with our model are then compared to the recorded seismic signals for well documented events.</p>

Explicit Finite Element Study of Liquid Sloshing Behavior in Fluid-Structure Interaction Condition

2017 ◽  
Author(s):  
Shuo Yang ◽  
Raymond K. Yee
Keyword(s):  
Finite Element ◽  
Water Level ◽  
Similarity Theory ◽  
Fluid Structure Interaction ◽  
Water Levels ◽  
Tank Wall ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
The Impact

As a common phenomenon in liquid motions, sloshing usually happens in a partially filled liquid tank of moving vehicle or structure. The objectives of this paper are to study sloshing behavior in rigid tank and deformable tank, and to develop a better performance baffle design in the tank under seismic excitations. The tank is surged with a sinusoidal oscillation about horizontal x-direction. The hydro-elasticity effect of sloshing pressure on the tank wall was taken into consideration due to the fluid-structure interaction between impact pressures and tank structures. ABAQUS finite element program using Coupled Eulerian-Lagrangian (CEL) technique was employed to simulate fluid sloshing. The sloshing phenomenon was studied in rigid tank and deformable tank models with three different water levels, and the effect of wall thickness of the deformable tank on sloshing behavior was discussed. One way to minimize the effect of sloshing in a tank, baffles are used and installed in the middle of the tank, and then various heights and material types of baffle were evaluated. The simulation results show that higher water level case creates greater pressure impact on the tank wall than lower water level case, and the elasticity of the tank structure would reduce the impact pressure of the wall. For the simulation tank model with size of 1m (H) × 1m (W) × 0.2m (D), better performance baffle was found to be the one with the height of 0.35m and was made of acrylic material. Moreover, the conclusion of this study can be extrapolated to other dimensions of the model based on similarity theory. This paper also can serve as an aid in further studying sloshing phenomenon. The findings of this study can be applied to restrain or minimize sloshing motions inside a tank.

Simulation of Thermal Fluid-Structure Interaction in Blade-Disc Configuration of an Aircraft Turbine Model

2014 ◽  
Author(s):  
Hannes Lück ◽  
Michael Schäfer ◽  
Heinz-Peter Schiffer
Keyword(s):  
Fluid Structure Interaction ◽  
Labyrinth Seal ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Sector Model ◽  
Implicit Approach ◽  
Coupling Approach ◽  
Disc Configuration ◽  
State Mixing ◽  
The Impact

This paper describes the impact of structural deformations on interstage cavity flow dynamics by adopting thermal fluid-structure interaction methods. These coupled numerical approaches solve the fluid-solid heat transfer in conjunction with the geometrical deformation due to mismatched centrifugal and thermal expansion of rotating and stationary turbine discs. Especially the changing clearances at the interstage labyrinth seal, at the rotor blade tips and at the rotor stator rim seals can be captured to calculate the correct flow physics at these locations. A manual explicit coupling approach in ANSYS is utilized that couples the CFX CHT solver with the FE solver Mechanical. The validation of a 3D sector model with experimental data shows improvements in predicting the metal temperature of the rotating walls but also disclose problems with the overheated stationary parts, mainly due to the utilization of steady state mixing planes. Additionally, a surrogate 2D model of the 3D model is introduced to compare the explicit coupling approach with an implicit approach exploiting the ANSYS MFX interface between the fluid and the solid domain. Thereby, the manual coupling approach reveals to be much more efficient for the examined thermal fluid-structure interaction.

scholarly journals Wave Propagation Across Solid-Fluid Interface With Fluid-Structure Interaction

2015 ◽  
Author(s):  
Tomohisa Kojima ◽  
Kazuaki Inaba ◽  
Kosuke Takahashi
Keyword(s):  
Wave Propagation ◽  
Theoretical Model ◽  
Characteristic Impedance ◽  
Fluid Structure Interaction ◽  
Fluid Interface ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Mechanism Of Wave Propagation ◽  
Free Falling ◽  
The Impact

This paper reports on investigations conducted with a view towards developing a theoretical model for wave propagation across solid-fluid interfaces with fluid-structure interaction. Although many studies have been conducted, the mechanism of wave propagation close to the solid-fluid interface remains unclear. Consequently, our aim is to clarify the mechanism of wave propagation across the solid-fluid interface with fluid-structure interaction and develop a theoretical model to explain this phenomenon. In experiments conducted to develop the theory, a free-falling steel projectile is used to impact the top of a solid buffer placed immediately above the surface of water within a polycarbonate tube. The stress waves created as a result of the impact of the projectile propagated through the buffer and reached the interface of the buffer and water (fluid) in the tube. Two different buffers (polycarbonate and aluminum) were used to examine the interaction effects. The results of the experiments indicated that the amplitude of the interface pressure increased in accordance with the characteristic impedance of the solid medium. This cannot be explained by the classical theory of wave reflection and transmission. Thus, it is clear that on the solid-fluid interface with fluid-structure interaction, classical theories alone cannot precisely predict the generated pressure.

Finite Element Approximation of Fluid Structure Interaction (FSI) Optimization in Arbitrary Lagrangian-Eulerian Coordinates

2013 ◽  
Author(s):  
Bhuiyan Shameem Mahmood Ebna Hai ◽  
Markus Bause
Keyword(s):  
Finite Element ◽  
Fluid Structure Interaction ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Special Cases ◽  
Non Linear ◽  
Non Linear System ◽  
The Impact

Advanced composite materials such as Carbon Fiber Reinforced Plastics (CFRP) are being applied to many aircraft structures in order to improve performance and reduce weight. Most composites have strong, stiff fibers in a matrix which is weaker and less stiff. However, aircraft wings can break due to Fluid-Structure Interaction (FSI) oscillations or material fatigue. This paper focuses on the analysis of a non-linear fluid-structure interaction problem and its solution in the finite element software package DOpElib: the deal.II based optimization library. The principal aim of this research is to explore and understand the behaviour of the fluid-structure interaction during the impact of a deformable material (e.g. an aircraft wing) on air. Here we briefly describe the analysis of incompressible Navier-Stokes and Elastodynamic equations in the arbitrary Lagrangian-Eulerian (ALE) frameworks in order to numerically simulate the FSI effect on a double wedge airfoil. Since analytical solutions are only available in special cases, the equation needs to be solved by numerical methods. This coupled problem is defined in a monolithic framework and fractional-step-θ time stepping scheme are implemented. Spatial discretization is based on a Galerkin finite element scheme. The non-linear system is solved by a Newton method. The implementation using the software library package DOpElib and deal.II serves for the computation of different fluid-structure configurations.

The Simulation of Dual Layer Fuel Tank During the Impact With the Ground Based on Parallel Computing

2007 ◽  
Vol 2 (4) ◽  
pp. 366-373 ◽  
Author(s):  
Li Zheng ◽  
Jin Xiang-long ◽  
Chen Xiang-dong
Keyword(s):  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Fuel Tank ◽  
Woven Fabric ◽  
Structural Domain ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Structure ◽  
Bisection Algorithm ◽  
Structure Interaction ◽  
The Impact

The crashworthiness of a dual layer fuel tank, with the outer layer made of metal and the inner layer made of woven fabric composite material, is fundamental for the survivability of an impact with the ground in emergency. In this research, the simulation of a three-dimensional dual layer fuel tank in the impact with the ground is achieved through the multimaterial arbitrary Lagrangian-Eulerian (ALE) finite element method because of its ability to control mesh geometry independently of geometry. At the same time, the naked flexible tank in the impact with the ground is simulated for the evaluation of the outer metal tank. The ALE description is adopted for the fluid domain, while for the structural domain the Lagrangian formulation is considered. The computation of the fluid-structure interaction and the impact contact between the tank and the ground are realized by the penalty-based coupling method. Then, the dynamic behaviors of the dual layer fuel tank and the naked flexible tank in the impact are analyzed. In the meantime, the parallelism of the dual layer fuel tank is discussed because the computation of the fluid-structure interaction and the impact contact is quite time consuming. Based on domain decomposition, the recursive coordinate bisection (RCB) is improved according to the time-consuming characteristics of fluid-filled tank in the impact. The result indicates, comparing with the RCB algorithm, that the improved recursive coordinate bisection algorithm has improved the speedup and parallel efficiency.

scholarly journals A GPU-Accelerated Compressible RANS Solver for Fluid-Structure Interaction Simulations in Turbomachinery

2016 ◽  
Author(s):  
L. Mangani ◽  
E. Casartelli ◽  
G. Romanelli ◽  
Magnus Fischer ◽  
A. Gadda ◽  
...  
Keyword(s):  
Computational Efficiency ◽  
Power Efficiency ◽  
Linear Time ◽  
Fluid Structure Interaction ◽  
Operating Conditions ◽  
Structural Deformation ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Non Linear ◽  
The Impact

Computational Fluid Dynamics (CFD) is a fundamental tool for the aerodynamic development in industrial applications. In the usual approach structural deformation due to aerodynamic and thermal loads is often neglected. However, in some cases, where power efficiency is the ultimate goal, an accurate prediction of the structure-flow interaction is essential. This is particularly true for trim and flutter analysis of aircrafts, helicopter and turbomachinery blades. Particularly, turbomachinery trim and flutter predictions still represent a challenge due to phenomena like rotor-stator interaction, separations and shock waves. The usual time-linearised, frequency-domain strategies can be inadequate when this kind of strong non-linear phenomena occur in the flow, making necessary full non-linear time-domain simulations or the harmonic balance technique. Beside flutter, another important aspect, not yet adequately investigated, is the trim analysis, which is fundamental for an accurate steady simulation that aims to consider static blade elasticity for the performance evaluation of turbomachines. Moreover, alongside the obvious contribution given by centrifugal loads to the blade deformation, a not less important source of blade displacement is the thermal effect due to the heat exchanged between the solid and the fluid domains. In particular, for some geometries and operating conditions, thermal effects can be more important than centrifugal effects for the blade deformations. Considering multiple sources of blade deformation (elastic, centrifugal and thermal) in a what is often called “multiphysics” approach is nowadays more and more important, if the goal of the analysis is geometry optimization. To achieve this, next to result’s accuracy also computational efficiency is required, when hundreds of aeroelastic simulations have to be performed in a typical optimization loop. Modern GPUs can be exploited to pursue this goal thanks to their high peak computational power available at relatively low costs and low power consumption with respect to the usual CPUs. In this paper a pioneer work describing the impact of static deformation due to blade elasticity, thermal and centrifugal effects on the performances and power efficiency will be provided. Alongside with accurate results, computational efficiency is taken into account. The purpose of this article is to show the architecture of a GPU-accelerated Fluid-Structure Interaction (FSI) solver for compressible viscous flows. The proposed approach is validated with a typical industrial case, i.e. a turbocharger transonic centrifugal-compressor provided by ABB. The effects of trimmed solutions on the most important integral quantities (i.e. mass flow, characteristic curves, mass-averaged outflow profiles) are investigated and a comparison with pure aerodynamic results is provided. Due to the high blade stiffness and thus the very small displacements obtained with the trim solutions, for the particular case presented in the paper the aeroelastic solutions basically provide nearly the same results as the pure aerodynamic solutions.

Numerical Approximation of Fluid Structure Interaction (FSI) Problem

2013 ◽  
Author(s):  
Bhuiyan Shameem Mahmood Ebna Hai
Keyword(s):  
High Speed ◽  
Fluid Structure Interaction ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Reinforced Plastics ◽  
Advanced Composite Materials ◽  
Special Cases ◽  
The Impact

Nowadays, advanced composite materials such as carbon fiber reinforced plastics (CFRP) are being applied to many aircraft structures in order to improve performance and reduce weight. Most composites have strong, stiff fibres in a matrix which is weaker and less stiff. However, aircraft wings can break due to Fluid-Structure Interaction (FSI) oscillations or material fatigue. The airflow around an airplane wing causes the wing to deform, while a wing deformation causes a change in the air pattern around it. Due to thrust force, turbulent flow and high speed, fluid-structure interaction (FSI) is very important and arouses complex mechanical effects. Due to the non-linear properties of fluids and solids as well as the shape of the structures, only numerical approaches can be used to solve such problems. The principal aim of this research is to explore and understand the behaviour of the fluid-structure interaction during the impact of a deformable material (e.g. an aircraft wing) on air. This project focuses on the analysis of Navier-Stokes and elastodynamic equations in the arbitrary Lagrangian-Eulerian (ALE) frameworks in order to numerically simulate the FSI effect on a double wedge airfoil. Since analytical solutions are only available in special cases, the equation needs to be solved by numerical methods. Of all methods, the finite element method was chosen due to its special characteristics and for its implementation, the software package DOpElib.

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