Abstract:Current studies on downbursts mainly employ impinging jet models. However, research on jet inclination angles remains limited, and small scaling ratios hinder investigations of downburst wind field characteristics. To address this, the study first investigated the wind field characteristics of inclined impinging jets using computational fluid dynamics (CFD), deriving an expression for the wind speed attenuation coefficient in the outflow region under different inclination angles. Subsequently, wall jets were used to simulate large-scale outflow wind fields in downbursts, but the effect of inclination angles on speed attenuation was neglected. Therefore, co-flow was in-troduced to mitigate viscous resistance around the jet. Smoke-wire wind tunnel tests and CFD methods were employed, yielding an expression for the co-flow-induced attenuation coefficient. Finally, the feasibility of simulating inclination-induced effects in downbursts using wall jets was evaluated. The results showed that: (1) the inclined impinging jet exhibited three-dimensional asymmetry. The atten-uation rate of the maximum horizontal wind speed on the front side decreased with increasing inclination angle, while the half-height wind speed in the wind profile increased by 77.8% at 30° inclination angle. (2) Smoke-wire wind tunnel tests and numerical simulations confirmed that wall jet wind fields resembled the frontside outflow section of downbursts, and the incorporation of co-flow effectively reduced the attenuation rate of horizontal wind speed. (3) By establishing a correlation between co-flow-induced and inclination-induced wind speed attenuation coefficients, it was feasible to simulate average wind profiles of downbursts at any inclination angle using wall jets, providing a novel approach for simulating largescale downbursts with inclination angles.
