ρ I am trying to estimate and validate the pressure of water exiting a nozzle. For an unknown reason, the validation is consistently twice as high as the estimation. Here the approach: Estimation: I am using the dynamic pressure equation for the estimation: q = 1/2 * ρ * u2 where, q = dynamic pressure ρ = density of water (997 kg/m3) u = liquid velocity The velocity is calculated based on the known nozzle diameter and the flow rate (u = flow rate / nozzle area) Validation: The measurement is performed by simply measuring the jet force with a force gauge in horizontal orientation and in short distance (<1cm) - see the schematic. The assumption is that the jet diameter is the same as the nozzle. q_val = jet force / nozzle area. As mentioned before, in varying measurements the validation is close to being twice of the estimation data. Is there anything I'm missing here?