Influence of a channel bend on the purging of saline fluid from a cavity by an overflow of fresh water

Abstract

A numerical and laboratory investigation on the purging of saline fluid from a cavity within a $60^\circ$~channel bend is presented to characterise the purging process in open channel bends. The numerical simulation uses a three dimensional, direct numerical simulation, fractional-step solver. The geometry replicates the laboratory experiment to define the mixing processes of a cavity with vertical sidewalls occupying the centre~$20^\circ$ of the $60^\circ$~channel bend. The secondary circulation as the flow moves through the bend increases the vertical momentum exchange within the cavity and hence destabilises the saline interface. References J. R. Anderson and A. K. Morrison. Environmental consequences of saline groundwater intrusion into the wimmera river, victoria. BMR. Journal of Australian Geology and Geophysics, 11:233--235, 1989d. S. Armfield and R. Street. An analysis and comparison of the time accuracy of fractional-step methods for the navier-stokes equations on staggered grids. International Journal for Numerical Methods in Fluids, 38(3):255--282, 2002. S. W. Armfield and W. Debler. Purging of density stabilized basins. International Journal of Heat and Mass Transfer, 36(2):519--530, January 1993. J. C. Bathurst, C. R. Thorne, and R. D. Hey. Secondary flow and shear stress at river bends. Journal of the Hydraulics Division, ASCE, 105 (HY10):1277---1295, 1979. H. Christie. Real-life management of an environmental water reserve, a wimmera perspective. In A.L. Wilson, R.L. Dehaan, R.J. Watts, K.J. Page, K.H. Bowmer, and A. Curtis, editors, Proceedings of the 5th Australian Stream Management Conference. Australian rivers: making a difference. Charles Sturt University, Thurgoona, New South Wales., 2007. W. Debler and S. W. Armfield. The purging of saline water from rectangular and trapezoidal cavities by an overflow of turbulent sweet water. Journal of Hydraulic Research, 35:43--62, 1997. P. H. Gaskell and A. K. C. Lau. Curvature-compensated convective transport: Smart, a new boundedness- preserving transport algorithm. International Journal for Numerical Methods in Fluids, 8(6):617--641, 1988. M. P. Kirkpatrick and S. W. Armfield. Experimental and large eddy simulation results for the purging of salt water from a cavity by an overflow of fresh water. International Journal of Heat and Mass Transfer, 48(2):341--359, January 2005. Henk A. van der Vorst. Iterative solution methods for certain sparse linear systems with a non-symmetric matrix arising from pde-problems. Journal of Computational Physics, 44(1):1--19, November 1981.