The paper focuses mainly on laboratory investigations of transient and transcritical flow in a single pipe of a sewer system. The aim of this paper is to present a comparison between pressure values calculated by an improved McCormack scheme and those measured at the hydraulic laboratory of the Gdańsk University of Technology, which were observed inside a pipe in an experiment for water flow with pressurization. The analysis proves that the numerical approach applied to flow simulation is a sufficiently accurate and reliable technique for predicting the basic parameters of storm sewer flow
In July 2016 in the Three-city agglomeration a rainfall episode of over a day duration and 150 mm summary rainfall height, occurred. This situation, extreme as for Polish conditions, caused significant freshets in rivers and streams running into Gdansk Bay, the Baltic Sea, and serving as collectors of rainfall waters for the sea-coast towns. In many areas of the Three-city flood phenomena and overflows took place. The flood also occurred in the catchment area of the Kacza river in Gdynia. The passing of flood water rise caused damage of many infrastructure objects located along the river valley. The estuary section of the river suffered most, especially sea-shore belt together with beach around the estuary which were significantly washed out. In this paper an approach was made to answer to the question on direct causes of the situation which occurred at the estuary of the Kacza river. To this end, there was worked out a hydrodynamic model of the considered section of the river, based on the solving of two-dimensional differential motion equations of free-surface liquid, and simulations of water flow propagation along the river’s valley were performed for a few variants of hydraulic engineering infrastructure of river bed. Numerical hydraulic analysis made it possible to determine a role of the hydraulic engineering objects in forming the flood water rise as well as their impact on location and range of washout zones of sea-shore belt.
Justyna Machalinska-Murawska and Michał Szydłowski
Two explicit schemes of the finite difference method are presented and analyzed in the paper. The applicability of the Lax-Wendroff and McCormack schemes for modeling unsteady rapidly and gradually varied open channel flow is investigated. For simulation of the transcritical flow the original and improved McCormack scheme is used. The schemes are used for numerical solution of one dimensional Saint-Venant equations describing free surface water flow. Two numerical simulations of flow with different hydraulic characteristics were performed - the first one for the extreme flow of the dam-break type and the second one for the simplified flood wave propagation problem. The computational results are compared to each other and to arbitrary solutions.