The purposes of this experiment are:1. Determine the shape of the wake behind the cylinder.2. Determine the calibration of the water tunnel. Both of these objectives were achieved using LDA (Laser Doppler Anemometry). LDA is one of the main velocity measurement methods used in professional experimentation. Light rays are fired from a laser onto flowing water. In the first objective, a cylinder was immersed in the water flow to determine how the velocity aft of the cylinder was disturbed. While the second objective used LDA on flowing water without disturbance. This LDA system is an accurate system. However, each system has some flaws that cause errors in the results provided. Particle averaging bias is the first of these errors. This bias states that when the velocity is high, the average velocity of the flow will be greater than the actual value. This occurs because more particle speeds are calculated compared to a slower flow. Another source of error is called velocity gradient broadening. This error arises from the fact that two particles at different positions in the gradient will have different speeds but will end up in the same measured volume. This will obviously give a change in speed where there shouldn't be one. Finally, there is an error called finite transit time broadening. This error occurs because the LDA system collects data using bursts of signals, which will fluctuate with each burst even if the flow rate is constant. Even though these three errors and others are observed when using an LDA system, it is still one of the most accurate systems used to calculate flow velocity. The first objective was examined by taking a series of data points with the laser configured to measure the velocity of the flow...... at the center of the paper...... in this experiment the shape of the wake behind the cylinder and calibrated the water tunnel. The conclusions are listed below:1. Horizontal flow velocities show that, as expected, a wake forms aft of the cylinder.2. Vertical flow velocities show that the flow is attempting to push the wake inward, from both the top and bottom, and return the water to its original state of steady flow.3. If you are using this particular system and the system does not calculate the flow velocity, move the laser slightly in any direction to obtain the values.4. Flow velocity versus pump velocity produces a linear graph with an R2 value of 0.99824 ± 0.00001.5. If the pump speed is doubled, the flow speed will also be doubled. Hence, ease of future experimentation.6. The water tunnel is well calibrated and can be used as an accurate test bed.