So far, several methods have been developed for water flow measurement. One of these methods is using flow meters that operate based on fluid oscillation. Fluidic oscillators that are used for measuring water flow typically comprise a body containing an inlet jet leading into a pair of channels separated by a splitter (or target). Downstream of the splitter the main channel includes two feedback loops that lead back to opposite sides of the path of the fluid that are adjacent the inlet jet. The inlet jet of fluid attaches to the wall of one of the channels by the Coanda effect. Then due to the flow of feedback channels that meet the inlet jet, the jet switches from one wall to the other. It causes pressure, velocity and some other fluid quantities to oscillate at the same frequency. According to the linear relationship between inlet velocity and jet oscillation frequency, the passed flow can be measured. There is no moving part in these flow meters. These flow meters are capable of low error. It is important especially at very low flows. In this research, considering the operating principles, a reverse engineering process is performed on an available flow meter. The X-Ray scanning method is used to identify the internal geometry. After processing the grayscale photos and measurement of dimensions, a prototype is designed and produced. Also, the trend of choosing appropriate sensor, sampling, and signal processing for extracting the oscillation properties are mentioned. For recognizing the oscillation and its frequencies’ characteristics in this prototype, a pressure transmitter and a piezoelectric element are utilized as sensors. In order to get precise information from water flow characteristics in water flow meter’s duct, and also finding an appropriate position for installing pressure-based sensors, the fluid flow is simulated numerically. For numerical study of transient (unsteady) flow by using CFX software, the duct is discretized. With regards to the fluid flow which is turbulent in a wide range of its operating Reynolds, the effects of some turbulence models, like K-? and SST K-? (Shear Stress traort K-?) are considered. Then the results of numerical solution by these models are validated by experimental results which are obtained from produced prototype. Identifying an appropriate position for installing sensor, extracting the characteristics graph of the system (Inlet velocity-Frequency of jet oscillation) and programming a software for acquiring sensor’s data, signal processing and calculating water flow automatically, are other things that have been performed. The capability of piezoelectric sensors for this application is evaluated by comparing its results with pressure transmitter’s ones. Finally, the main effects of the important geometric parameters on system performance in very low Reynolds numbers are evaluated. In this research the full factorial DOE is performed for three 3-level factors and the mean analysis method is used to analyze changes of the factors through those levels. By increasing the inlet width as well as the target distance, the operating Reynolds have decreasing and increasing trend. But by increasing target width the operating Reynolds is decreased. This analysis shows that these geometric factors in available flow meter had been chosen with regards to the requirement of having permanent oscillations between diffuser-shaped walls in low Reynolds numbers. Key Words:Fluidic oscillator flow meter, Turbulence numerical simulation, Sampling, Signal processing,Pressure sensor, Piezoelectric sensor, Full factorial.