SmartPIV: flow velocity estimates by smartphones for education and field studies

Abstract

In this paper, a smartphone application is presented that was developed to lower the barrier to introduce particle image velocimetry (PIV) in lab courses. The first benefit is that a PIV system using smartphones and a continuous wave (cw-) laser is much cheaper than a conventional system and thus much more affordable for universities. The second benefit is that the design of the menus follows that of modern camera apps, which are intuitively used. Thus, the system is much less complex and costly than typical systems, and our experience showed that students have much less reservations to work with the system and to try different parameters. Last but not least the app can be applied in the field. The relative uncertainty was shown to be less than 8%, which is reasonable for quick velocity estimates. An analysis of the computational time necessary for the data evaluation showed that with the current implementation the app is capable of providing smooth live display vector fields of the flow. This might further increase the use of modern measurement techniques in industry and education. Graphic abstract

Smartphone-based particle image velocimetry for cardiovascular flows applications: A focus on coronary arteries

“…Second, the combination of the (fixed) maximum acquisition frame rate of the smartphone camera and the use of a continuous light source resulted in particle blurring in correspondence of the stenosis ( Supplementary Figures S4, S7 ), with the consequence of underestimating local velocity values ( Figure 8 ) starting from 40 cm/s. To reduce particle blurring, a possibility could be offered by the adoption of a cw laser pulsed by a frequency generator, as suggested by Cierpka et al, 2021 , or a pulsed low-power light source ( Aguirre-Pablo et al, 2017 ; Käufer et al, 2021 ; Minichiello et al, 2021 ) to illuminate the image sensor for a short time, although this solution would require a synchronization unit. Particle blurring ( Oh et al, 2021 ) could potentially be reduced also by decreasing the exposure time.…”

“…Taken together, these considerations underline the theoretical benefits offered by a PIV system relying on the combined use of smartphone cameras and low-energy light sources in terms of costs, simplicity, and safety. In the followings, we will refer to such a PIV system as “smart-PIV”, as introduced in a recent study presenting a smartphone-based PIV dedicated software application ( Cierpka et al, 2021 ). To date, the practical feasibility, range of applicability and related performances of a smart-PIV approach in biomedical applications have not yet been clearly defined.…”

Optimizing recording speed and interrogation window for rotating flow recorded in the ambient light: PIV analysis

“…In PIV analysis, signi cant technological advancement has provided alternatives for the high-tech equipment, e.g., high-power pulsed lasers can be replaced with high-power LEDs and high-speed professional cameras with smartphone cameras, which in turn makes the overall PIV system safe, simple, easy to operate, and notably economical (Kashyap et show good agreement with the standard stereo-PIV data for the same ow. Simultaneously, mobile-based applications for PIV measurement, such as mIPIV and smartPIV, have been developed from the educational perspective (Minichiello et al 2020;Cierpka et al 2021). It provides the live visualization of ow, allows users to capture the ow at various fps, and gives the data as a text le and vector image (Cierpka et al 2021).…”

“…Both these studies show good agreement with the standard stereo-PIV data for the same flow. Simultaneously, mobilebased applications for PIV measurement, such as mIPIV and smartPIV, have been developed from the educational perspective (Minichiello et al 2020;Cierpka et al 2021). It provides the live visualization of flow, allows users to capture the flow at various fps, and gives the data as a text file and vector image (Cierpka et al 2021).…”

“…Simultaneously, mobilebased applications for PIV measurement, such as mIPIV and smartPIV, have been developed from the educational perspective (Minichiello et al 2020;Cierpka et al 2021). It provides the live visualization of flow, allows users to capture the flow at various fps, and gives the data as a text file and vector image (Cierpka et al 2021). In all these papers, either high-power lasers or high-power LEDs have been used.…”