Predictions of Heat and Mass Transfer in Open Channels

by Ashok K. Rastogi, Research Engr.; Univ. of Karlsruhe, Karlsruhe, West Germany,
Wolfgang Rodi, Research Engr.; Univ. of Karlsruhe, Karlsruhe, West Germany,

Serial Information: Journal of the Hydraulics Division, 1978, Vol. 104, Issue 3, Pg. 397-420

Document Type: Journal Paper

Abstract: The paper describes a three-dimensional model for calculating the distribution of velocity, temperature, and pollutant concentration in open channel flows, and a depth-averaged two-dimensional version for situations with insignificant stratification and secondary currents. Both models are restricted to parabolic flows where influences cannot be transmitted upstream. The turbulent stresses and heat/concentration fluxes appearing in these equations are determined from the so-called k-ϵ turbulence model that solves differential transport equations for the turbulence kinetic energy k and the rate of its dissipation ϵ. In the depth-averaged model, the bottom shear stress, surface heat flux and turbulence production due to bottom shear are accounted for by source/sink terms in the relevant equations. The 3D calculations compare favorably with available measurements. The 2D and 3D predictions agree well for high Froude numbers; for a Froude number of 5 they agree only for the rough bed, while for the smooth bed they start to deviate significantly at a Froude number of 10.

Subject Headings: Shear stress | Turbulence | Froude number | Three-dimensional models | Three-dimensional flow | Two-dimensional models | Temperature distribution | Velocity distribution |

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