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Abstract
In this study, the turbulent characteristics of the flow in an open channel with horizontal and inclined impermeable beds were studied experimentally using two-dimensional particle image velocimetry (PIV). The experiments were conducted in a channel of 6.5 m in length, 7.5 cm in width and 25 cm in height. The slope of the channel was S = 0 for the horizontal impermeable bed and for S = −0.002, S = −0.004 and S = −0.006 for the inclined impermeable bed. Hydraulic characteristics such as distributions of velocities, turbulent intensities and Reynolds stress are investigated at a fine resolution using the PIV. Velocity is measured above the horizontal and inclined impermeable bed for the same different heights (h = 5, 7, 9, 11 and 13 cm) and for the same different discharges (Q = 0.735, 0.845 and 0.970 lt/s). Results show that the channel slope influences significantly near the impermeable bed but not near the free surface the variation of turbulent characteristics of the flow and also the alteration of the channel slope from −0.002 to −0.006 doesn't influence the variation of turbulent characteristics of the flow, which are the longitudinal turbulent intensity u′U*, the vertical turbulent intensity v′/U* and the turbulent kinetic energy. The channel slope doesn't influence the Reynolds stress.
Notations
The following symbols are used in this paper:
| h: | = | flow depth above the impermeable bed (cm) |
| Q: | = | discharge (lt/s) |
| S: | = | channel slope |
| U*: | = | friction velocity (m/s) |
| Umean: | = | mean velocity of flow above the impermeable bed (m/s) |
| y: | = | distance from the impermeable bed (cm) |
| u′: | = | horizontal turbulent intensity (m/s) |
| v′: | = | vertical turbulent intensity (m/s) |
| = | turbulent shear stresses (pascal) | |
| κ: | = | von Karman constant |
| v: | = | kinematic viscosity (m2/s) |
| μ: | = | dynamic viscosity (kg/m·s) |
| ρ: | = | water density (kg/m3) |
| τ0: | = | wall shear stress (pascal) |
| ϵ: | = | porosity |
Disclosure statement
No potential conflict of interest was reported by the author.