Time-periodic pulse electroosmotic flow of Jeffreys fluids through a microannulus

In this article, we investigate the time-periodic pulse electroosmotic flow (EOF) of Jeffreys fluids through a microannulus. By using the Laplace transform method, the velocity expression of the pulse EOF is derived. The effect of some variables on the time it takes for the fluid to go from a static state to a flowing state is analyzed. We find that increasing the relaxation time (lambda) over bar (1) and decreasing the inner and outer radius ratio alpha will result in longer time for the fluid to reach the flowing state, but the retardation time (lambda) over bar (2) and the inner and outer zeta potential ratio beta have little effect on it. The impact of some related parameters on the pulse EOF velocity for different inner and outer radius ratios (alpha) is discussed in detail. The results show that for a smaller inner and outer radius ratio alpha, the velocity amplitude increases with the relaxation time (lambda) over bar (1) and decreases with the retardation time (lambda) over bar (2). As the inner and outer radius ratio alpha increases, the effect of relaxation time (lambda) over bar (1) on velocity amplitude gradually weakens or even becomes insignificant, and the effect of the retardation time (lambda) over bar (2) on the velocity amplitude remains unchanged. Moreover, the velocity amplitude will decrease with the increase in the inner and outer radius ratio alpha and its change range will expand from the electric double layer near the annular wall to the entire flow region.