Take-off threshold velocity of saltating particles under heat radiation
EXPERIMENTS IN FLUIDS
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A wind tunnel and a heating device were designed in order to study the influence of solar radiation on the wind-induced motion of solid particles. Velocity and temperature measurements in the boundary layer exhibited clear modifications of flow characteristics with a surprising balance between the viscosity increase and the reduction in the wall velocity gradient. This induces a constant critical wall shear stress under heat flux. Measurements of threshold velocity undertaken to elucidate the possible effects of solar radiation through the increase in turbulence intensity showed a reduction in critical free-stream velocity as the free-stream turbulence increased.