Jong S. Kim  Jung Ho Lim  You Huh

Vol. 54,  No. 4, pp. 278-286, Aug.  2017
10.12772/TSE.2017.54.278

flow field staples average speed linear density fluctuations disturbances mode field length Spectrum

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This study deals with the dynamic characteristics of staples flowing in a onedirectional flow field, when external forces exerted on the staples are generated at both the ends of the flow field. Based on a theoretical model describing fiber bundle flow dynamics, we introduced the effect of staple length on model parameters such as the speed variance of individual staples and the kinematic viscosity of staples through a beard diagram. Simulations for investigating the dynamic behaviors of the staple flow variables, namely, the average speed of the staples and the linear density of the staple bundle, were conducted numerically with respect to time and position in the flow field under predetermined conditions. The results indicated that the output linear density of the staple bundle has a periodic change, which could be explained by the dynamic behavior of the staples in the flow field. The dynamic distribution of the average speed of staples has a continuously increasing profile, which changes with time. Thus, the change in speed distribution leads to fluctuations in the linear density of the staple bundle. The acceleration of the staple bundle also fluctuated with time, which got stronger while approaching the exit of the flow field. This indicates that the output staple bundle could be very sensitive to the disturbances occurring near the exit. The fluctuation in output linear density was influenced by the length of the flow field. When the length of the flow field is short (the ratio of the field length to the maximum staple length is approximately 1.1), the fluctuation in linear density has a single peak in the amplitude spectrum. However, when the flow field becomes longer (the ratio of the field length to the maximum staple length is approximately 1.5), the spectrum of the linear density fluctuation shows multiple peaks.