Jet impingement is considered to be an effective technique to enhance the heat transfer rate, and it finds many applications in the scientific and industrial horizons. The objective of this paper is to summarize heat transfer enhancement through different jet impingement methods and provide a platform for identifying the scope for future work. This study reviews various experimental and numerical studies of jet impingement methods for thermal-hydraulic improvement of heat transfer surfaces. The jet impingement methods considered in the present work include shapes of the target surface, the jet/nozzle–target surface distance, extended jet holes, nanofluids, and the use of phase change materials (PCMs). The present work also includes both single-jet and multiple-jet impingement studies for different industrial applications.

Double feedback fluidic oscillators, which create oscillating fluid jets, are commonly used in flow control and thermal applications. The geometry of the Coanda surface affects the oscillation frequency, jet deflection angle, and pressure drop in the mixing chamber. This study numerically investigates the impact of rib locations on the Coanda surface on jet characteristics. Air, with an inlet velocity of 55.8 m/s, is used as the working fluid. Three cases—full ribs, upper ribs, and lower ribs—are compared to a smooth Coanda surface. The full ribs case achieves an increased oscillation frequency of 820 Hz, compared to 355 Hz for the smooth case. However, the jet deflection angles decrease when ribs are present. The upper ribs case achieves a larger 41.5° deflection angle, while the full ribs case achieves a relatively lower 33.8° angle. Interestingly, adding ribs to the Coanda surface reduces the pressure drop in the oscillator. Oscillators with upper ribs achieve a 76.1% increase in FDPR compared to smooth cases, making them the best solution for enhancing the combined effect of jet oscillation frequency and deflection angle.

Numerical simulations of incompressible laminar flow past a circular cylinder using wavy wall confinement are performed in order to study drag reduction and vortex shedding suppression for Reynolds numbers (50 ≤ Re ≤ 280) and blockage ratios (0.5 ≤ D/H ≤ 0.9), where D is the cylinder diameter and H is the channel height. The optimum configuration of wavy wall confinement is identified to have an amplitude of 0.2D and wavelength of 4D which manifests the minimum drag coefficient and complete vortex shedding suppression (zero lift coefficient). The flow over the cylinder with optimized wavy wall confinement produces a stable vortex pair in the wake of the cylinder. The length of vortex pair in the wake increases by increasing the Reynolds number and decreasing the blockage ratio. The drag on the cylinder reduces when the length of vortex pair increases due to early flow separation and reduction in pressure drag. The drag coefficient decreases by 36% in comparison to the plane wall confinement at D/H = 0.5. The drag coefficient decreases for wavy wall configuration by about 67% for D/H = 0.7 and 94% for D/H = 0.9. The lift coefficient remains zero at all Reynolds numbers and blockage ratios which indicates complete suppression of vortex shedding.

This numerical investigation employs a two-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) approach with the k-ω SST turbulence model to systematically evaluate the impact of bleed-feed channel geometry (with three width variations: 0.2D, 0.25D, and 0.3D) on double feedback fluidic oscillator performance. The focus is on improving oscillation frequency and heat transfer while reducing pressure drop, which are critical parameters in fluidic oscillator-driven jet impingement cooling applications. Addressing these challenges is essential to enhance cooling performance, minimize energy consumption, and enable reliable thermal management in advanced engineering systems. The study analyzes key performance parameters, including oscillation frequency, pressure drop, and heat transfer characteristics, comparing channel-enhanced designs against a baseline smooth oscillator. Results demonstrate that incorporating a bleed-feed channel significantly enhances performance, with the 0.3D width emerging as optimal, delivering a 150% increase in oscillation frequency and a 3.2% reduction in pressure drop compared to the smooth design. These improvements are attributed to the channel’s ability to strengthen feedback flow, thereby accelerating jet switching while minimizing energy losses. Thermally, the 0.3D configuration achieves a 7.3% higher Nusselt number than the smooth oscillator, resulting from combined effects of higher oscillation frequency (intensifying boundary layer disruption) and increased jet momentum from reinforced feedback flow. The progressive performance enhancement across the three channel widths (0.2D to 0.3D) reveals clear geometry–performance relationships. These findings provide valuable insights for optimizing fluidic oscillator designs in applications requiring high-frequency oscillations and targeted cooling, such as electronics or gas turbine blade cooling.