PhD and Masters by research theses (SoE)

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Browsing PhD and Masters by research theses (SoE) by Supervisor "Asproulis, N."

Now showing 1 - 4 of 4
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    Computational nanoscience and molecular modelling of shock wave interactions with biological membranes
    (Cranfield University, 2011) Sourmaidou, Damiani; Asproulis, N.; Drikakis, Dimitris
    Lateral diffusion of membrane components (lipids and proteins) is an important membrane property to measure since the essential process of absorption of anti-cancer and other drugs -some of which are not soluble in lipids and therefore would not be able to penetrate the cell membrane through passive diffusion- lies on it. In particular, the procedure of diffusion into the cell cytoplasm is reliant on free volumes in the membrane (passive diffusion) as well as carrier proteins (facilitated diffusion). By enhancing the mobility of lipids and/or proteins, the possibility of the carrier protein to "encapsulate" pharmacological components maxim- izes, as a "scanning" of the proteins gets performed due to the fluid phase of a biological membrane. At the same time, the increased mobility of the lipids facilitates the passage of lipid-soluble molecules into the cell. Thus, given that the success of anticancer treatments heavily depends on their absorption by the cell, a significant enhancement of the cell mem- brane permeability (permeabilisation) is rendered vital to the applicability of the technique. For this reason, there is augmented interest in combined methods such as Nanotechnology based drug delivery that is focused on the development of optimally designed therapeutic agents along with the application of shock waves to enhance the membrane permeability to the agents. This study examines the impact of shock waves on a numerical model of a biological membrane. Cont/d.
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    High-order methods on mixed-element unstructured meshes for aeronautical applications
    (Cranfield University, 2012-11) Antoniadis, Antonis F.; Drikakis, Dimitris; Asproulis, N.
    Higher resolution and reliability are the desiderata for Computational Fluid Dynamics and main drivers for the development, implementation and validation of highorder accurate methods. Complex fluid dynamic phenomena such as shock-wave boundary-layer interactions, turbulent separated flows and fluid problems involving multiple scales are adequately resolved with high-order schemes. The spatial representation of the flow field by an unstructured mesh provides flexibility, automation, fast and effortless grid generation and exceptional load balance on multiple processor computers. This plethora of advantages is mirrored by the unprecedented popularity of unstructured-based schemes. The objective of this PhD project is the implementation of two high-order schemes for the compressible Navier-Stokes equations in the context of the finite volume “kexact” framework: the MUSCL-TVD and WENO. The schemes are formulated in two and three space dimensions for mixed-element unstructured meshes; in addition, the Spalart-Allmaras turbulence model is implemented into the developed numerical framework. A wide range of applications are considered spanning from low-speed flows (M = 0.08) to supersonic conditions (M = 5.0); inviscid and viscous simulations in a broad spectrum of Reynolds numbers ranging from Re = 500 up to Re = 37×106. The applications include: the Taylor-Green vortex, the ONERA-M6 wing, flat plate, the NACA-0012 and the MD 30P-30N aerofoils, and a shock-wave boundary-layer interaction. For the examined cases, WENO schemes demonstrate superior accuracy, numerical dissipation and non-oscillatory behaviour over the MUSCL-TVD. High-order schemes inherit low numerical dissipation properties while turbulence models induce dissipation, this disequilibrium has adverse effects on the stability, convergence and accuracy of the simulation; therefore, turbulence model re-calibration would be required in order to accommodate high-order discretisation methods.
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    Life cycle assessment of composites and aluminium use in aircraft systems
    (Cranfield University, 2013-10) Liu, Ziqian; Asproulis, N.; Kolios, Athanasios
    As a consequence of the gradually expanding aviation network, civil aircrafts are occupying an increasingly high proportion of the transport industry. Air transport now dominates the intercity rapid transit, long-distance passenger transport, international passenger and freight transport, and specific regional transport, advantaged as it is by fast, convenient, comfortable and safe options. Nevertheless, the potential adverse impact on the environment of air transport, specifically, in the case of this research, the pollutants generated during aircraft production remain a concern. Using the A319 as the main research object, this thesis will conduct a life cycle assessment research about its environmental impact. Moreover, it will focus on the impact brought by the application of composite materials to the entire life cycle environmental influence of the aircraft, particularly the material production and disposal process. At the same time, a contrast with the B737-800 aircraft will be made due to their different composite material use rate. Firstly, the inventory list is formed by collecting data about the weight and material of every component in the aircraft, the input and output information of the composite material manufacturing process, the disposal situation of the aircraft and the treatment of composite material. Secondly, the impact assessment of the aircraft is conducted to examine their environmental influence. During the assessment, each life stage and the whole life cycle of the aircrafts is assessed, and a comparison between these two aircraft types is made. Finally, according to the impact assessment result, the environment load increase brought by the manufacturing of composite material and the decrease of the environment impact due to the weight reduction character of composite material is calculated and compared. From this research, the conclusion that the use of composite material has a positive effect on decreasing the environmental impact of the whole life cycle of the aircraft is obtained. This will enable aircraft manufacturers to target these reas for improvement, to produce more comfortable, environment friendly and market competitive aircraft.
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    Wind farm and environmental aerodynamics assessment using computational engineering
    (Cranfield University, 2011-08) Zoumprouli, Argyro; Asproulis, N.
    The aim of this thesis is the application of computational engineering software for the study of wind resource assessment of a wind farm as well as for establishing the range of influence of different numerical and physical parameters, including turbulence modeling , surface roughness and wakes. Simulations were performed for a wind farm which is in operation since 2006, called Panachaiko, located at the west part of Greece and encompassing an energy capacity of 34.85 MW. Simulations were performed using three variants of the k-ε model. Moreover, the effects of surface roughness and wake on the efficiency of wind farm operation were investigated. Comparisons were performed between linear and non-linear computational fluid dynamics (CFD) modeling, in the framework of the available engineering (commercial) software. Both qualitative and quantitative assessment of the results is presented. The study revealed the dependence of the results on the CFD (linear vs non-linear) model employed. The results of the present study provide useful guidance regarding the applicability of CFD models for wing resource assessment.
**Copy of record** Please note that the electronic theses currently available on this server have been originally submitted in a paper format. In all cases the bound paper thesis is the copy of record.