Abstract
Transition between free-surface and pressurized flows is a crucial phenomenon in many hydraulic systems. During simulation of such phenomenon, severe numerical oscillations may appear behind filling-bores, causing unphysical pressure variations and computation failure. This paper reviews existing oscillation-suppressing methods, while only one of them can obtain a stable result under a realistic acoustic wave speed. We derive a new oscillation-suppressing method with first-order accuracy. This simple method contains two parameters, Pa and Pb, and their values can be determined easily. It can sufficiently suppress numerical oscillations under an acoustic wave speed of 1000 ms−1. Good agreement is found between simulation results and analytical results or experimental data. This paper can help readers to choose an appropriate oscillation-suppressing method for numerical simulations of flow regime transition under a realistic acoustic wave speed.
Highlights
In water conveyance systems, water flows under free-surface flow condition or pressurized flow condition
Numerical oscillation is a critical problem in transient mixed flow simulations
These numerical oscillations arise from the ambiguity about the locationin of the filling-bore within computational
Summary
Water flows under free-surface flow condition or pressurized flow condition. Despite of all the fine properties that finite volume methods have, the numerical oscillations in a flow regime transition simulation have troubled many hydraulic engineers [12]. These numerical oscillations have the same origin with “post-shock oscillations” in gas dynamics [20,21,22,23]. A lot of effort has been spent to obtaintoa stable accurate of flow regime [12,23,24] This existing paper, some existing oscillation-suppressing area tested on a benchmark.
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