High-resolution particle image velocimetry was employed to investigate the near-wall boundary layer (BL) in viscoelastic polymeric flows subjected to pressure gradient (PG) effects in a mesoscale water channel. The flow was driven over a converging surface with varying favorable PG (V-FPG), a flat surface with constant FPG (C-FPG), and a diverging surface with varying adverse PG. This study examines the interplay between viscoelasticity and FPG in shaping BL dynamics. Velocity statistics measured on the channel midplane are reported for Newtonian water and non-Newtonian polyacrylamide solutions at concentrations of 200 and 400 p.p.m., with and without PG effects. In fully developed C-FPG polymeric flows, mean streamwise velocity fluctuations increased markedly with concentration, with peak dimensional values enhanced by $\approx 58\%$ and $\approx 87\%$ at the highest flow rates compared to water. Accelerating polymer solution flows exhibited elevated edge-to-mean velocity ratios and relaminarized regions in the converging section due to strong FPGs. Inner-normalized mean velocity profiles deviated from the classical log law depending on the local PG and skin friction. The combination of V-FPG and polymer viscoelasticity strongly suppressed Reynolds shear stresses, with peak dimensional values reduced by $\approx 80\%$ and $\approx 89\%$ in accelerating 200 and 400 p.p.m. flows relative to water. These findings provide new insights into the coupled effects of PGs and viscoelasticity on wall-bounded turbulence, offering guidance for improved numerical modeling and engineering design in complex flow systems.

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• Turbulence
• Non-Newtonian fluids
• Particle image velocimetry