Implementing a Low Cost, Mobile, Particle Image Velocimetry Application to Improve Fluid Dynamics Education

Despite fluid dynamics’ foundational role in mechanical, aerospace, biological, civil, naval, and ocean engineering, introductory fluids courses have been observed to dissuade undergraduate engineering students from pursuing fluids related research and careers. Among the reasons for this professional “gate-keeping” are that undergraduate courses are mathematically intensive, relying on a large amount of analytical problem solving in place of hands-on experimentation. As well, fluid dynamics principles are rarely taught before college resulting in a lack of early intuition and interest in the subject. As a result, engineering undergraduates often describe introductory fluids courses as procedurally and conceptually difficult while lacking visual appeal and connection to real world flows. Flow visualization is a hands-on aspect of fluid dynamics which is vital for related research and industry. Engineering educators may also use flow visualization techniques to develop students’ fluids related intuition, garner interest, and reduce attrition.

Among these flow visualization techniques, Particle Image Velocimetry (PIV) is a state-of-the-art method which allows researchers to see and analyze velocity fields in a variety of settings. PIV uses laser optics to illuminate a thin sheet of “seeding particles” added to a fluid of interest. This allows the particles to be imaged by a digital camera. A solution software then compares the time series of images capturing the area of illuminated particles and the particle displacements between images are reported in the form of vector fields. Most PIV experiments, however, are expensive due to the cost of laboratory grade cameras and lasers (typically thousands of dollars). As well, a high level of expertise is required to functionally operate most PIV systems (i.e. understanding of imaging techniques, computer coding, and PIV correlation methods) while ensuring the safe use of medium and high-powered lasers (i.e. Class 3B, Class 4).

This poster presents the current design and practical implementation of a low-cost, open-source mobile PIV application that enables engineering students to examine velocity fields without the high cost and prior level of expertise associated with PIV. This application (mI-PIV) guides users (who are PIV novices) step-by-step in the data collection and analysis. The mI-PV application enables students to illuminate seeding particles within flow experiments using a low-powered, hand-held laser (e.g. laser pointers, laser diodes) and image particle displacements on their personal smartphones running Android. As well, the mI-PIV application contains “micro-learning” modules that teach students about PIV correlation methods, digital imaging, fluid dynamics, and laser safety.

To demonstrate mI-PIV in practice, we present a low cost and easily constructed vortex ring experiment to enable high school students to qualitatively visualize the aesthetically interesting vortex ring formation and translation. High school students may also use Bernoulli equations to estimate a mean outlet velocity and compare to experimental results. This experiment also allows undergraduate students to estimate the vortex ring characteristics as a function of initial conditions and compare measured values to analytical solutions. Experiments and hands-on engagement by students will provide educational data for iterative design improvement. Further development of the mI-PIV application and experiments will enable students to develop and solidify interest and intuition related to fluid dynamics.