Simulations were performed to examine the effects of a coiled tube after a T-junction on the mixing and flow characteristics. A coiled tube was found to have two effects:inducing a radial flow and flattening the axial velocity distribution

which enhances and weakens the mixing

respectively. In the straight tube section connecting the T-junction and coiled tube

the latter may dominate and cause the mixing to deteriorate. An experiment was performed with the Villermaux/Dushman method to verify the simulation results. Based on a mixing performance simulation with various fluid and geometric structure parameters

a dimensionless correlation was obtained that can be used to determine the mixing intensity along the coiled tube with a deviation of less than 1.5%. These results provide guidance for designing a coiled tube or optimizing the operating conditions to meet the mixing requirements of specific chemical processes.