Student projects

All the texts (in Danish) are available at The Library of Roskilde University RUB. Some of the projects are also published as IMFUFA texts. The "IMFUFA texts" are a series of projects and papers by students and researchers at IMFUFA, and can be bought by contacting IMFUFA. A few of the projects are also available for download from this page.

Projects written as part of my master studies
Dielectric and Shear Mechanical Relaxation in Glass Forming Liquids (Master thesis)
Topological study of the von Carman vortex shedding
Handling of momentum at sources and sinks in C. S. Peskin's 2D-Heart-model
Models and measuring on the shear modulus of super-cooled liquids near the glass transition
Projects written as part of my final year of bachelor studies
Symmetry in physics
Cayleys problem

The goal of this thesis is to elucidate whether a relation can be established between shear mechanical and dielectric relaxation in glass forming liquids. The starting point is a generalized Debye model, which has been proposed by DiMarzio and Bishop [J.Chem.Phys. 60 (1974) 3802].

The DiMarzio-Bishop model is thoroughly analyzed and reformulated in such a way that different unphysical simplifications that have been used earlier, are avoided. New testable qualitative predictions of the DiMarzio-Bishop model are formulated and the model is put in a form where quantitative tests can be made by using only one macroscopic parameter.

The DiMarzio-Bishop model is tested by extensive dielectric and shear mechanical measurements on various molecular liquids. The shear mechanical measurements are performed using a transducer that has been developed at IMFUFA by Christensen and Olsen [Rev. Sci. Instrum. 66 (1995) 5019]. This transducer allows measurements to be made in an exceptionally large frequency range (1mHz-50kHz). The systematic errors and uncertainties of the two measuring methods are analyzed in detail. Furthermore these errors and uncertainties are taken into account in the reformulation and tests of the DiMarzio-Bishop model.

It is found that the DiMarzio-Bishop model to a large extend has qualitative agreement with our data and data from the literature, whereas the quantitative agreement is moderate or poor depending on the liquid tested. This suggests that the model is too coarse grained to capture details of the relaxation processes, but that it does in fact capture the fundamentals of the physics involved, and consequently that there is a direct relation between shear mechanical relaxation and dielectric relaxation.

The Von Carman Vortex shedding is the pattern seen when fluid passes a cylinder, and it is a classical problem in fluid dynamics. Using tools from the qualitative theory of dynamical systems (bifurcation theory) we proposed a simple model describing the formation and shedding of the vortexes, and found results that agree with numerical simulations.

We worked with a Fluid Dynamic model of the heart, discussing what the appropriate equations should be. We developed new physical based methods for analysing the results from the model, and did numerical analysis on large amounts of data.

Models and measuring on the shear modulus of super-cooled liquids near the glass transition

We designed and tested a mechanical device for measuring the shear modulus of viscoelastic super-cooled liquids. The project included working with continuum mechanics, piezoceramic devices, modelling of mechanic and piezoceramic systems, computer controlled experiments and data analysis.

In this project we discussed what role symmetry play in physics. We have looked at the way symmetry leads to laws of conservation (in classic and quantum mechanics) and discussed the way symmetry is a fundamental part of modern Physics.

Cayleys problem