One Camera, Two Fields: A Minimalist Approach to PIV-LIF Diagnostics

Simultaneous measurement of velocity and scalar fields has long been a central challenge in turbulence research, particularly for advancing closure models for interactions between passive or active scalars and the underlying velocity field. While numerical simulations have increasingly succeeded in generating high-fidelity scalar and velocity field data, experimental approaches remain limited by hardware cost, physical, and optical constraints. In this work, we present a novel, cost-effective imaging strategy to overcome some of these barriers. We introduce high-quality ultra-low-cost fluorescent (Nile Red) tracer particles that when paired with a fluorescent dye (Rhodamine-6G) of distinct emission characteristics, simultaneous PIV and LIF field can be successfully extracted from light intensity map captured with a single camera. Utilizing a canonical turbulent round jet flow, a series of experiments spanning varying particle image densities and dye concentrations is conducted to evaluate the method's performance, highlighting both its capabilities and limitations. To benchmark the single-camera system, a second camera with a longpass filter captures isolated particle images for standard velocity (PIV) field comparison.