In order to determine the flow pattern in the TC reactor, the Reynolds number based on the gap size has been adopted, as defined by
\(Re=\frac{\omega_{i}r_{i}d}{\nu}\) (17)
where ωi and ri are the angular velocity and the radius of the inner cylinder, respectively.d is the gap size, and ν is the kinematic viscosity of the suspension. In this study, various cases with different Reynolds number have been investigated by changing the rotational speed of the inner cylinder. The critical Reynolds number (Rec ), which indicates the presence of Taylor vortex flow was found to be about 97 with the classical inner circular cylinder (i.e., radius ratio\(\ \eta=\frac{r_{i}}{r_{o}}=0.8\)). When the Reynolds number exceeds the critical Reynolds number, the flow pattern will experience a series of instabilities, including wavy Taylor vortex flow and turbulent Taylor vortex flow, which can finally develop into turbulent Taylor flow (Grossmann et al. , 2016).