Wall Shear Measurment in Sand-Water Mixture Flows

by Oner Yucel, (A.M.ASCE), Asst. Prof.; Dept. of Civ. Engrg., Middle East Technical Univ., Ankara, Turkey; formerly, Post-Doctoral Research Assoc., Dept. of Civ. Engrg., Lehigh Univ., Bethlehem, Pa.,
Walter H. Graf, (M.ASCE), Prof. and Dir. of Hydraulics Lab.; Swiss Federal Inst. of Tech., Lausanne, Switzerland; formerly, Assoc. Prof. and Dir. of Hydr. and Sanit. Engrg. Div., Dept. of Civ. Engrg., Lehigh Univ., Bethlehem, Pa.,

Serial Information: Journal of the Hydraulics Division, 1975, Vol. 101, Issue 7, Pg. 947-963

Document Type: Journal Paper


The wall shear stress was measured in clear-water and sand-water mixture flows with the use of a flush-mounting hot-film shear-sensor. Data were obtained with two shear-sensors and two different sands (d50 = 0.45 mm and d50 = 0.88 mm) with solids concentrations of up to Cmax = 1.6% by volume, and for flow Reynolds numbers of 105 < RD < 6 x 105. The measured sensor wall shear stresses were compared with the true wall shear stresses obtained with the energy head loss measurements conducted in a pipeline system. The results of the tests in the clear-water flows confirmed the relationship between the sensor power output, PS, and the wall shear stress, τo, given by τol/³ = APS + B, in which A and B are calibration coefficients. The tests with the low-concentration sand-water mixtures in a vertical pipe indicated that for the present range of experiments, sensor power outputs with the mixtures exceeded those for clear-water by an average of 5%. It is shown that the shear-sensors are delicate but accurate instruments that can be used for the measurement of the wall shear stress.

Subject Headings: Shear stress | Shear walls | Flow measurement | Probe instruments | Shear flow | Soil mixing | Sand (material) | Sandy soils

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