In this paper, the performance of the fluidic oscillator with resonance channel and vortex amplifier is numerically investigated. The unsteady flow generated in this oscillator is simulated in the three-dimensional model with the assumption of turbulent flow using the DES model. The effects of different geometric parameters on the output frequency of the oscillator were investigated by changing the height of the resonance channel, placing triangular, square, and circular splitters, changing the splitter distance from the supply nozzle and, changing the state of control nozzles. Results indicate that the highest frequency variation is due to the change of the distance between the supply nozzle and splitter. By changing the splitter distance, the output frequency varies from 11 to 66 Hz. Reducing the height of the resonance channel leads to an increase in the output frequency. It has also been shown in the results that the frequency achieved using a triangular splitter is lower than square and circular splitters. Moreover, the output frequency is shifted with different output angles, achieving the highest frequency (43.48 Hz) using the 40-degree angle. A characteristic curve correlating the oscillation frequency (f) with the outlet area angle (theta) was obtained, which is expressed as = -0.0009 theta(3) + 0.05538 theta(2) + 0.581 theta -18.4. (c) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.