Dyeing Rate of Nylon 6 Fabric and Yarn Assemblies with p-Aminoazobenzene

The dyeing rates of p-aminoazobenzene on nylon 6 fabrics and yarn assemblies at 40°C have been investigated. The apparent diffusion coefficient and the diffusional boundary layer parameter are estimated in such a way that the experimental data fit the theoretical rate curve based on the diffusional boundary layer model. Because the boundary layer parameter can be separated into two distinct components, the relationship between each component and the dyeing condition and the structure of the textile assembly is examined. The component concerned with the dye-fiber-dyebath combination or composition is subdivided into several groups. The component determined by the fluid-flow pattern and rate is dependent on the magnitude of the inter-yarn spaces.

Dyeing Rate of Nylon 6 Yarn with p-Aminoazobenzene

The dyeing rate of p-aminoazobenzene on nylon 6 yarn at 40°C has been investigated. The apparent diffusion coefficient and the diffusional boundary layer parameter are estimated in such a way that the experimental data fit with the theoretical rate curve based on the diffusional boundary layer model. The dyeing behavior of the yarn is discussed in relation to the pore size of the spaces between individual filaments.

Simulation of Viscous Diffusion for Extension of the Surface Vorticity Method to Boundary Layer and Separated Flows

A numerical method for two-dimensional incompressible viscous fluid flows is tested on the diffusion of a point vortex. It is then applied to the boundary layer to reconstruct the Blasius profile, to demonstrate flow separation, and to simulate turbulence. The significance of Thwaites' boundary layer parameter for flow separation is explained. The Kelvin-Helmholtz instability, which is responsible for two-dimensional turbulence, is represented by the motion of an array of point vortices after an initial disturbance. The formation of the Von Karman vortex street downstream of a circular cylinder is described by computer simulation, and the influence of viscous diffusion is shown. For two different cylinder Reynolds numbers the vortex shedding frequencies and oscillating lift and drag forces are evaluated.