DSpace Collection:
https://dspace.lboro.ac.uk/2134/4642
2017-12-13T17:01:33ZHydrophobicity, solvation and structure formation in liquids
https://dspace.lboro.ac.uk/2134/27536
Title: Hydrophobicity, solvation and structure formation in liquids
Authors: Chacko, Blesson
Abstract: In this thesis we use density functional theory (DFT) to study the solvent mediated interactions between solvophobic, solvophilic and patchy nanostructures namely rectangular cross section blocks. We calculate both the density profiles and local compressibility around the blocks and the results obtained for our model system provide a means to understanding the basic physics of solvent mediated interactions between nanostructures, and between objects such as proteins in water, that possess hydrophobic and hydrophilic patches. Our results give an improved understanding of the behaviour of liquids around solvophobic objects and solvophobicity (hydrophobicity) in general.
Secondly, we look into the physics incorporated in standard mean-field DFT. This is normally derived by making what appears to be a rather drastic approximation for the two body density distribution function: ρ(2)(r,r′) ≈ ρ(r)ρ(r′), where ρ(r) is the one-body density distribution function. We provide a rationale for why the DFT often does better than this approximation would make you expect.
Finally, we develop a lattice model to understand the nature of the pattern formation exhibited by certain systems of particles deposited on liquid-air interfaces and in particular the nature of the transitions between the different patterned structures that are observed. This is done using Monte Carlo computer simulations and DFT and links the observed microphase ordering with the micellisation process seen e.g. in surfactant systems.
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.2017-01-01T00:00:00ZA spin-coefficient approach to space–times with torsion
https://dspace.lboro.ac.uk/2134/27380
Title: A spin-coefficient approach to space–times with torsion
Authors: Jogia, Shashi C.
Abstract: The Newman–Penrose formalism, which has been extremely useful
in general relativity, is extended to include the possibility
of space–times with torsion. Initially Riemann–Cartan geometry
is discussed and the torsion and contortion tensors are defined.
The possible alternative but equivalent approaches in developing
the formalism are given in Chapters 3 and 4. These involve the
use of tetrads and spinor dyads. In the definition of the spin
coefficients, the components of the contortion tensor appear as
correction terms to the spin coefficients defined in the associated
Riemannian space–time. [Continues.]
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.1981-01-01T00:00:00ZNumerical simulation of warm discharge in cold fresh water
https://dspace.lboro.ac.uk/2134/27376
Title: Numerical simulation of warm discharge in cold fresh water
Authors: George, Alabodite M.
Abstract: Buoyant plumes in cold fresh water are of interest because of the possibility of buoyancy reversal due to the nonlinear relation between temperature and density in water. Thus an initially rising plume may become a fountain. This project aims to mathematically model such plumes and fountains using numerical simulation by the means of a commercial software, Comsol Multiphysics. Both turbulent and lam- inar cases were investigated in different geometries, and with the assumption that density is a quadratic function of temperature. The turbulent flow cases as con- sidered here in this thesis are relevant to practical applications such as industrial discharge in cold lakes: whereas, the laminar flow case relates to laboratory experi- ments which are typically at scales too small for the flow to be turbulent. Previous investigation on warm discharge placed more attention on the biological implications of the spread along the lake bed, and not interested in analysing the dynamics of such flow, which turns out to be our focus. Furthermore, investigations on buoyant plumes that become negatively buoyant at later time (fountain flow) as considered previously, are based on the assumption that density is a linear function of tem- perature: where entrainment always reduces buoyancy. Whereas, the consideration of the temperature of maximum density is crucial and realistic in many practical situations, especially the power station warm discharge. Mixing is then bound to produce a mixture that is denser than both the discharge and the ambient water if receiving water is less than Tm: where this situation differs from plumes with linear mixing properties. Therefore, our focus is to better fathom the behaviour of warm discharge so as to give a detailed description of the flow, and also to observe buoyancy reversal whenever water that is denser than both the discharge and the receiving water is produced. The simulations were carried out for Prandtl number Pr = 7 & 11.4 and over the ranges of Froude number 0.1 ≤ Fr ≤ 5 and Reynolds numbers 50 ≤ Re ≤ 106, with source temperatures that are assumed to be higher than the temperature of maximum density Tm, and the ambient water below the Tm. Our results show some distinct behaviours from those experimental investigations by Bukreev, who also considered warm discharge where water that has temperature above the temperature Tm is initiated into a medium below Tm. The results here also showed some differences from those investigations with the linear dependence relation assumption.
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.2017-01-01T00:00:00ZA numerical study of some hybrid conjugate gradient methods in optimal control
https://dspace.lboro.ac.uk/2134/27361
Title: A numerical study of some hybrid conjugate gradient methods in optimal control
Authors: Mohammadi, Seyed A.
Abstract: The main work of this thesis is concerned with the comparison of conjugate
gradient with hybrid conjugate gradient methods when they are applied
to optimal control problems. Descriptions of the conjugate gradient. and
hybrid conjugate gradient methods, for general optimisation, in finite and
infinite dimensions are also given. The numerical methods for solving the
differential equations and the line searches required in the optimisation are
discussed next. [Continues.]
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.1995-01-01T00:00:00Z