The angle is chosen so that the probe has the greatest sensitivity under the desired operating conditions. However, commercial probes use . Such probes are most sensitive in measuring isotropic turbulence for which . Let and be the Cartesian components of velocity and and be the effective velocities sensed by the wires. The voltage outputs and of wires 1 and 2 will correspond to the effective velocities and respectively. One can calibrate wires 1 and 2 individually in uniform parallel flow and generate the calibration curves and for each of them. This is schematically in Figure 2.13.