Yarn Balloons, Differential Geometry and the Navier-Stokes Equations

Publication Type:
Thesis
Issue Date:
2023
Full metadata record
In the textile industry, there are hundreds of millions of ring spindles or equivalent devices in use today around the world converting millions of tonnes of short staple fibers such as cotton or polyester into clothing and other textiles. The aim of this thesis is to improve the mathematical model of yarn spinning devices to potentially lead to an improvement in the efficiency of the production process. Past research in this area, referred to as the Padfield model, expressed the yarn balloon equations in cylindrical polar coordinates, in a reference frame rotating with a constant angular velocity. The air drag was assumed to be proportional to the velocity normal to the yarn squared, while the tangential component was neglected, and the drag coefficient $C_D$ was assumed to be equal to 1 for all values of the Reynolds number $Re$, because the exact functional relationship between $C_D$ and $Re$ is not known. The ultimate objective of this thesis is to improve the accuracy of the mathematical model of this system by representing the yarn balloon equations in intrinsic coordinates, and finding a more accurate representation of the air drag term in these equations along the entire length of the yarn balloon. This is achieved by finding a new exact similarity solution of the 2-D incompressible steady state Navier-Stokes equations which will enable significant progress to be made in finding the functional relationship between $C_D$ and $Re$ for $0 < Re < 47$. The process through which this similarity solution is used to find the corresponding physical solution is described in detail for $0 < Re < 47$. The viscous solution in the boundary layer is matched to the inviscid external solution so that all boundary conditions are satisfied. This is significant progress towards improving the mathematical model of yarn spinning devices through finding the relationship between $C_D$ and $Re$ for low Reynolds numbers. The solution found here also has more applications than just the yarn balloon problem, and thus a greater importance.
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