Author(s): Loose Franciszek

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Abstract: The effect of surface cover which simulates herein ice-cover on mixing processes was investigated in a straight rectangular channel. Heated water was discharged /separately/ on three different levels i. e. at the bottom, at the surface and in the middle of the flow depth. For the comparative purposes, the parameters of several experiments /discharges and temperatures of channel and heated water flows, flow depth/ were similar for considered cases: free surface flow, covered flow with a smooth underside of cover and covered flow with a rough underside of cover. As it was earlier documented by other authors, the ice-covered flows required larger flow depth of transport the same discharge with the same bed slope. So if the flow depth and discharge were kept the same, the velocities were larger in both considered covered channel flows. In consequence, the heat transfer differs for these investigated cases. The decrease of the maximum water temperatures is more rapid in the free-surface flow than in the ice-covered flows. It allows to conclude that channel covers tends to reduce the mixing rate. The difference in the mixing process is the largest when the outlet of the heated water is at the surface and the smallest when the outlet is situated at the bottom.

DOI:

Year: 1990