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The dramatic and fast growth of aeronautics over a century has led to a humongous amount of aircraft in the skies. This number being in constant increase, the aeronautical industry is developing new planes and new technologies at a relentless rhythm. On top of that, environmental goals targeted during the last decades put some pressure on the sector when it comes to the gas emissions. Therefore, the need of a tool being able of accurately and rapidly predicting the aerodynamics and the fuel consumption of an aircraft during its preliminary design became urgent. 

High fidelity models, such as the Navier-Stokes equations or Low Eddy Simulations are not adequate since they require a large computational cost and it takes a very long time to obtain the results. Even the standard in aircraft design, the Reynolds-Averaged Navier-Stokes equations is not the best option. As a matter of fact, the required time (of the order of hours) is still too much to be able to perform quick modifications during the early stages of the preliminary design. A viable candidate is the full potential equation. Such a model provides very fast results at a low computational cost. 

Many comparisons have shown that interesting results were obtained on deformed wings by performing linear computations coupled with a fluid-structure interaction solver as these results were quite close to the results directly obtained from nonlinear computations. The purpose of this master thesis is then to implement a field panel method, called fpm, solving the linear potential equation and coupling it to an already existing fluid-structure interaction solver in order to compute the aerodynamics of a wing in its deformed configuration. The results of the computations can then be used to analyse the aeroelasticity of the wing as well as its aerodynamic coefficients (that can directly relate to the performance of the aircraft and, somehow, to its fuel consumption). 

The results presented in this work revealed that a good match between the results of the coupling and nonlinear results was obtained. Furthermore, a larger comparison with many results from the literature also strengthened this observation. It was also shown that aeroelasticity and thus fluid-structure interaction is a non-negligible phenomenon that significantly influences the aerodynamics of a wing. For instance, it decreases the lift coefficient while increasing the drag coefficient. The modification of the aerodynamic parameters can have a serious impact on the design and the performance of an aircraft, ultimately resulting in an unpredicted fuel consumption.

Field Panel Method --- Aeroelasticity --- CFD --- C++ --- Python --- Ingénierie, informatique & technologie > Ingénierie aérospatiale

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Modern aircraft design relies on the usage of computational fluid dynamics for the prediction of aerodynamic performance. High fidelity methods such as the Reynolds-Averaged Navier-Stokes (RANS) equations are too computationally expensive for early design stages such that a simpler method known as viscous-inviscid interaction can be used instead. The inviscid flow is calculated and is corrected by the viscous flow in the boundary layer. The coupling between the two regions is complex and prone to numerical issues.

The present work aims to compare steady and unsteady coupling strategies to solve for steady-state problems within the BLASTER solver. The existing inviscid solver is replaced by an incompressible panel method in its steady and unsteady forms. The viscous solver is also adapted to allow for unsteady simulations; the pseudo time marching algorithm and transition treatment in BLASTER are modified accordingly. 
The missing elements for a complete unsteady model are identified and discussed. 

The steady and unsteady coupling strategies are compared based on speed, accuracy and stability for different test cases in various flow regimes of interest. The unsteady coupling shows better stability and faster convergence especially for high incidence flows with separation. This advantage is diminished as the incidence decreases and the flow becomes simpler. For all cases, both strategies yield similar results with little to no difference. The low-Reynolds number flow proves to be challenging for the solver, and its divergence is not resolved by the unsteady coupling strategy.

The method is also tested on true unsteady pitching cases. Understanding the limitations of the model, simple conditions can be predicted with good accuracy compared to RANS simulations. Nonetheless, the solver lacks the ability to predict fast motion, and suffers from issues when refining the time step.

Viscous-inviscid interaction --- Panel method --- Viscous flow --- Ingénierie, informatique & technologie > Ingénierie aérospatiale

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This book presents the papers accepted into the Special Issue “Stability and Seakeeping of Marine Vessels” and includes nine contributions to this Special Issue published in 2020. The overall aim of the collection is to improve knowledge about the most relevant and recent topics in ship stability and seakeeping. Specifically, the articles cover a wide range of topics and reflect the recent scientific efforts in the 2nd generation intact stability criteria evaluation and modelling of the ship dynamics assessment in intact or damaged conditions. These topics were investigated mainly through direct assessments performed both via numerical methods and tools, and experimental approaches. The book is addressed to individuals from universities, research organizations, industry, government agencies and certifying authorities, as well as designers, operators and owners who contribute to improved knowledge about “stability and seakeeping”.

URANS --- VOF --- overset mesh --- side damage --- bottom damage --- flooding process --- motion response --- nonlinear steady flow --- desingularized Rankine panel method --- forward speed --- radiation and diffraction --- adaptive weather routing --- Seakeeping Performance Index --- route optimization --- Dijkstra algorithm --- Cummins equations --- vertical motions assessment --- time domain simulations --- experimental seakeeping --- hard chine displacement hull form --- second generation intact stability criteria --- operational guidance --- operational limitations --- vulnerability levels --- direct stability assessment --- Ro-Ro ferry --- coastal patrol ship (CPS) --- full-scale seakeeping trials --- ship design --- barge platform --- zero-pressurized air cushion --- hydrodynamic performance --- boundary element method --- container ship --- added resistance in waves --- sea states --- potential flow theory --- variation of ship characteristics --- strip theory --- BEM --- RANS --- regular wave --- seakeeping --- n/a

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The problem of solving complex engineering problems has always been a major topic in all industrial fields, such as aerospace, civil and mechanical engineering. The use of numerical methods has increased exponentially in the last few years, due to modern computers in the field of structural mechanics. Moreover, a wide range of numerical methods have been presented in the literature for solving such problems. Structural mechanics problems are dealt with using partial differential systems of equations that might be solved by following the two main classes of methods: Domain-decomposition methods or the so-called finite element methods and mesh-free methods where no decomposition is carried out. Both methodologies discretize a partial differential system into a set of algebraic equations that can be easily solved by computer implementation. The aim of the present Special Issue is to present a collection of recent works on these themes and a comparison of the novel advancements of both worlds in structural mechanics applications.

History of engineering & technology --- direction field --- tensor line --- principal stress --- tailored fiber placement --- heat conduction --- finite elements --- space-time --- elastodynamics --- mesh adaptation --- non-circular deep tunnel --- complex variables --- conformal mapping --- elasticity --- numerical simulation --- numerical modeling --- joint static strength --- finite element method --- parametric investigation --- reinforced joint (collar and doubler plate) --- nonlocal elasticity theory --- Galerkin weighted residual FEM --- silicon carbide nanowire --- silver nanowire --- gold nanowire --- biostructure --- rostrum --- paddlefish --- Polyodon spathula --- maximum-flow/minimum-cut --- stress patterns --- finite element modelling --- laminated composite plates --- non-uniform mechanical properties --- panel method --- marine propeller --- noise --- FW-H equations --- experimental test --- continuation methods --- bifurcations --- limit points --- cohesive elements --- functionally graded materials --- porosity distributions --- first-order shear deformation theory --- shear correction factor --- higher-order shear deformation theory --- equivalent single-layer approach --- direction field --- tensor line --- principal stress --- tailored fiber placement --- heat conduction --- finite elements --- space-time --- elastodynamics --- mesh adaptation --- non-circular deep tunnel --- complex variables --- conformal mapping --- elasticity --- numerical simulation --- numerical modeling --- joint static strength --- finite element method --- parametric investigation --- reinforced joint (collar and doubler plate) --- nonlocal elasticity theory --- Galerkin weighted residual FEM --- silicon carbide nanowire --- silver nanowire --- gold nanowire --- biostructure --- rostrum --- paddlefish --- Polyodon spathula --- maximum-flow/minimum-cut --- stress patterns --- finite element modelling --- laminated composite plates --- non-uniform mechanical properties --- panel method --- marine propeller --- noise --- FW-H equations --- experimental test --- continuation methods --- bifurcations --- limit points --- cohesive elements --- functionally graded materials --- porosity distributions --- first-order shear deformation theory --- shear correction factor --- higher-order shear deformation theory --- equivalent single-layer approach

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The problem of solving complex engineering problems has always been a major topic in all industrial fields, such as aerospace, civil and mechanical engineering. The use of numerical methods has increased exponentially in the last few years, due to modern computers in the field of structural mechanics. Moreover, a wide range of numerical methods have been presented in the literature for solving such problems. Structural mechanics problems are dealt with using partial differential systems of equations that might be solved by following the two main classes of methods: Domain-decomposition methods or the so-called finite element methods and mesh-free methods where no decomposition is carried out. Both methodologies discretize a partial differential system into a set of algebraic equations that can be easily solved by computer implementation. The aim of the present Special Issue is to present a collection of recent works on these themes and a comparison of the novel advancements of both worlds in structural mechanics applications.

History of engineering & technology --- direction field --- tensor line --- principal stress --- tailored fiber placement --- heat conduction --- finite elements --- space-time --- elastodynamics --- mesh adaptation --- non-circular deep tunnel --- complex variables --- conformal mapping --- elasticity --- numerical simulation --- numerical modeling --- joint static strength --- finite element method --- parametric investigation --- reinforced joint (collar and doubler plate) --- nonlocal elasticity theory --- Galerkin weighted residual FEM --- silicon carbide nanowire --- silver nanowire --- gold nanowire --- biostructure --- rostrum --- paddlefish --- Polyodon spathula --- maximum-flow/minimum-cut --- stress patterns --- finite element modelling --- laminated composite plates --- non-uniform mechanical properties --- panel method --- marine propeller --- noise --- FW-H equations --- experimental test --- continuation methods --- bifurcations --- limit points --- cohesive elements --- functionally graded materials --- porosity distributions --- first-order shear deformation theory --- shear correction factor --- higher-order shear deformation theory --- equivalent single-layer approach --- n/a