Quantitative evaluation of PIV peak locking through a multiple Δt strategy: relevance of the rms component

摘要: The possibility of using different times between laser pulses (Δt) in a PIV (Particle Image Velocimetry) measurement the same real flow field for error assessment has already been proposed by authors recent paper Nogueira et al. (Meas Sci Technol 20, 2009). It is simple procedure that available with usual setup. In work, peak locking was considered basically as bias error. Later measurements indicated that, appropriate processing algorithms, this not main peak-locking effect. Scenarios rms (root mean square) due to most relevant contribution are more common than initially expected and require differentiated approach. This issue impact evaluation quantities like turbulent kinetic energy. first part work centred on showing always towards closest pixel integer displacement. Insight subject indicates case only algorithm-induced locking. coming out image acquisition limitations (i.e. resolution) ‘a priory’ biased. random peculiar probability density function. Discussion offered, particular approach use multiple Δt strategy asses proposed. results reveal images where amplitude assessed be small 0.02 pixels, errors can order 0.1 pixels. As approaches maturity, providing quantitative confidence interval estimating seems essential. method developed robust enough quantify these values presence turbulence up ~0.6 proposal constitutes step forward from traditional histogram-based considerations whether strong present or not, without any information its magnitude origin rms.