PIV velocity field measurement-based pressure gradient computation

A description of the basic operation principles of the (particle image velocimetry) PIV velocity field measurement-based pressure gradient calculations and three different methods were described in detail. Then, an analytic test case of the convection of a Gaussian vortex was considered to give insight into the influences of the discrete scheme, parameter setting and flow field characteristic on successful determination of the pressure gradient field. Results showed that the uncertainty of pressure gradient calculation was dominated by errors of PIV velocity measurements. The effect of 1% errors in velocity on the result was about two orders of magnitude higher than any other steps. Time and spatial resolution settings were not as high as possible, but there was a suitable intermediate value. The Lagrangian approach was superior to the Euler approach in most cases, but the former became worse when the flow structure was more complex, the pressure gradient calculation method should be selected according to the flow type and flow field characteristics.