Stability of a liquid thread and stability and nonlinear evolution of multi-layer fluid flow

This thesis is concerned with stability and existence of waves in interfacial and free surface problems. Considered is the curtain coating problem, with specific emphasis on trilayer and bilayer flows, and the breakup of a viscous thread with a solid core. Experiments on curtain coating and sheet breakup are mostly conducted by industry and as such are hidden in patents or kept secret by companies trying to gain an edge in a competitive market. Experiments on curtain breakup concentrating on the effect that surfactants have upon the stability and the effect of differing fluid properties are discussed. It is shown that multiple layers of different fluid are more stable when reducing the flow rate of the lowest layer. Single and multi-layer fluid flow down an inclined plane is studied with the emphasis on the effect of an insoluble surfactant. Bilayer and trilayer flow down an inclined plane is considered. The main point of interest here is the existence of multiple unstable modes for a single set of parameters. A long wave model describing the multi-layer flow is discussed. Time-dependent solutions to this model system lead to the discovery of travelling wave solutions present in the dynamics. The travelling wave solutions are further investigated through Fourier analysis leading to the discovery of branches of solutions emerging from wavenumbers for which the flow is neutrally stable. The normal mode stability of annular Stokes flow of a viscous thread with a solid core is discussed which extends work done for negligible viscosity and small wavenumbers.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2016

Author dc:creator

• Thompson, Julian

Language dc:language

en