Abstract: High-density algal cultivation is important for the efficient use of biomass resources. To address the issue of how poor water movement affects the growth and production of microalgae, this paper looked at how the speed of the water flow and the effects of swirling motion in the photobioreactors (PBR) differ, using a special tool called the Time-resolved Particle image Velocimeter (TR−PIV) to measure the growth rate and turbulent kinetic energy of Chlorella. The study compared how the liquid flows and creates eddies in the photobioreactors, and it produced diagrams showing the flow rate, size of the eddies, and turbulent kinetic energy, while also measuring the growth rate and carotenoid content of Chlorella vulgaris. The experimental results indicated that the flow with high axial velocity, high radial velocity, high eddy volume (0.015−0.025 s⁻¹), and high TKE (≤ 0.2 m²/s²) accelerated the division and growth of Chlorella cells and the production of high value−added products and that visualizing the flow field is an effective tool for the design and optimization of PBR. The method for visualizing the experimental flow field is an effective tool for the design and optimization of PBR.