Safe Flight Envelope Prediction and Experimental Validation of Multirotor UAV: An Analysis on the Effects of Longitudinal Center of Gravity Position and Actuator Dynamics on Quadcopter Flight Envelopes

Loss of control (LOC) is the primary cause of failure of Unmanned Aerial Vehicles (UAV). The safety of these systems can be largely improved by facilitating techniques to prevent LOC to occur, such as Flight Envelope Protection, enabling controllers to keep the system within the Safe Flight Envelope (SFE).<br/>The aim of this work is to examine...

An Interface-enriched Topology Optimization for Mitigating the Effect of Surface Flaws in 3D Brittle Structures

In this 3D fracture-based topology optimization framework, the author extended the 2D framework on tailoring fracture resistance for brittle materials (Zhang et al., 2022) to 3D. In the optimization, the topology is described by radial basis functions interpolated level set function, and the problem is solved by the Interface-enriched...

Optimal designs with topology optimisation

The level-set approach in the field of topology optimisation has been studied thoroughly the last two decennia, but there is a lack of challenging standard benchmark problems. Besides two standard benchmark problems, this master's thesis tackles one difficult benchmark problem in particular: the inverter. For every benchmark the minimum...

Study of droplet dynamics in transcritical environments

Efficient combustion processes are indispensable in limiting the temperature increase to 1.5 deg C as set by Intergovernmental Panel on Climate Change (IPCC) before 2030 to curtail the effects of global warming. As for the emissions, the main task lies in controlling the air-fuel ratio in the lean regime as to control the emissions of NOx since...

A volume-conserving interface-correction level-set method on unstructured triangular meshes

The level-set (LS) method uses a signed-distance function to capture the interface in two-phase flows. Geometrical properties can be easily obtained, and merging and splitting of the interface are handled automatically by the LS method. However, it is not inherently volume conserving. Several methods found in literature that aim to solve this...

Laying the Groundwork for a New Thick Level Set Method

In this thesis, the basis for a general implementation of the Thick Level Set method is presented. This basis combines the general applicability of the TLS_V1 method by Moës et al. with the improved fracture mechanics of the TLS_V2 method by Lé et al. In order to accomplish this, the topological skeleton needs to be found for an arbitrary...

Vertical Motion Simulation Of A DTMB 5415M Ship In Head Sea Using The Variational Multi-scale Method

This master thesis presents the computation of free-surface flow phenomena with emphasis on ship hydromechanics. We perform a simulation of the heave and the pitch motion of the DTMB 5415M ship moving in head sea. To this purpose we employ an existing Arbitrary-Lagrangian-Eulerian residual-based variational multiscale method (ALE-RBVMS) to...

An innately mass conserving interface capturing method for the modelling of interface advection on unstructured grids

In solving two-phase flows, the location of the interface between the phases is necessary to handle interface jump conditions when solving the Navier-Stokes equation. Current interface capturing and advection methods, however, suffer from various issues. The level set method uses the signed distance to the interface and the interface being the...

Modeling and simulating three phases of steel: Austenite, ferrite and cementite

In the work of Den Ouden the level-set method has been used to model the growth and dissolution in a steel alloy of the precipitate cementite and the diffusive phase austenite. The movement of the interface between the two phases is controlled by the diffusion of carbon and a reaction on the interface between the two phases. In this thesis...

FSI Analysis and Optimization of 3D beam structures

Aiming to enhance the performance of the industrial design process, structural optimization techniques have been proposed as an alternative to traditional design and optimization techniques.<br/>They own the potential of achieving an optimal distribution of the material through the design domain, thus reducing waste loss and weight, and...

Post-Processing of Topology Optimized Results: A method for retrieving smooth and crisp geometries

Structural design optimization is the process of obtaining an optimized structure while satisfying a set of criteria. The process can be divided into three stages: topology optimization (stage one), geometry extraction (stage two) and shape optimization (stage three). The last two stages are regarded to be the post-processor of topology...

Development and implementation of moving boundary conditions in the Material Point Method

A new technique is developed in this thesis, which applies boundary conditions to moving boundaries in the Material Point Method (MPM). While MPM has been proven to be useful in slope stability, foundation and seabed ploughing modelling, the application of boundary conditions is still a challenge,<br/>because the location of the boundary is...

Structural Design Optimization of Vibration Isolating Structures

The design of high performance instruments often involves the attenuation of poorly damped resonant modes. These resonant modes are a limiting factor to the performance of these instruments. Current design approaches typically start from a baseline design and introduce stiffening or damping reinforce- ments to tune and/or damp these modes....

Numerical modelling of droplet formation in mesh nebulizers

It is common practice to use the inhalation route to deliver medicine in the form of aerosol to treat patients with pulmonary ailments like cystic fibrosis. In pulmonary drug delivery, medicine in the form of small droplets is inhaled by patients and delivered to their lungs. A major challenge faced in developing such devices is that effective...

Simulation of drying and ?ooding in a tidal embayment using the level set method