Laboratory investigation of the effect of hysteresis phenomenon of supercritical flow on the rough bed on the relative residual energy parameter

Abstract

In the present study, the hysteretic behavior of supercritical flow that can occur in a channel near additional structures, such as changes in the bed of the channel, has been investigated experimentally and analytically. For this purpose, two diameters of the channel floor materials of 1.12 and 2 cm have been used. The critical depth ranges from 2.7 to 4.5 cm and the used flow rates range from 250 to 600 liters per minute. The flow rate increases in the primary flow and then decreases in the secondary flow into the laboratory flume. The possible flow regimes near the narrowed section are classified based on the relative depths and relative energy remaining in sections 1 and 2 as a function of the Froude number passing under the valve. The results show that by increasing the flow rate and then decreasing it, in some flow rates, two different behaviors can be seen from the flow in the same laboratory conditions. Also, the results showed that with the increase in the diameter of the bed material, the remaining relative energy values have increased a lot, so that in the primary flow, the amount of these depths indicates the subcritical regime, and in the secondary flow, with the formation of hysteresis phenomenon in some discharges, it indicates the regime Also, with the increase in the average diameter of the material, the hysteretic behavior of the flow becomes more intense.

Keywords

• hysteretic behavior
• possible flow regimes
• rough bed
• relative depth
• relative residual energy