Naslov
Influence of the Outflow Boundary Conditions in the Open Channel and Shallow Water Models

Autori
Družeta, Siniša ; Črnjarić-Žic, Nelida ; Kranjčević, Lado

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of 4th International Congress of Croatian Society of Mechanics / Matejiček, Franjo - Zagreb : Hrvatsko društvo za mehaniku (HDM), 2003, 137-144

Skup
4th International Congress of Croatian Society of Mechanics

Mjesto i datum
Bizovac, Hrvatska, 18.09.2003. - 20.09.2003

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
open channel flow; shallow water; outflow boundary conditions; domain size

Sažetak
Boundary conditions can have an important effect on the simulation results. Inappropriate use of boundary conditions can significantly distort the results, which could in case of open channel and shallow water models lead to seriously over or under-estimated water levels and flooded areas. As it is always necessary to choose the appropriate boundary condition type, it is sometimes also very important to have them sufficiently distant from the domain areas of specific interest. This means the computational domain sometimes needs to be larger than the physical domain, so the modeler could be assured that no possible specific boundary-condition-based effects would alter the result at the domain area of interest. The outflow boundary conditions used for the survey presented in this paper were discharge - water depth dependency function for 1D open channel model and nonreflecting (transmissive) boundary condition for 2D shallow water model. The inquiry of the influence of the used boundary conditions was conducted through series of simulations with different domain lengths (for 1D model) and sizes (for 2D model). Simulations were carried out with software package SOPEX STRIPP12, used for river flow and flooding simulation. For subcritical flow, channel shape information downstream of the outflow boundary typically affects the flow properties upstream of the outflow boundary, to an extent. However, the results shown indicate that chosen outflow boundary conditions influence the computed water level almost along the whole of the domain. Since both 1D and 2D outflow conditions used in this paper fictionally generate uniform flow downstream of the domain boundary, two basic rules seem to emerge. Outflow boundary should be positioned either in the lengthy channel section along which the actual flow is predominantly uniform, or sufficiently away from the location of interest. Results presented in this paper suggest that sufficient distance for this would be huge, which indicates that further investigation of this problem is needed.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne tehničke znanosti

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