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Developed for almost 40 years, our 1D solver has become one of the fastest and most robust solutions available, making it an ideal choice for flood modelling applications.

The industry-leading 1D steady and unsteady solvers provide a comprehensive range of methods for simulating flows and water levels. It can be confidently applied to applications ranging from steep river flows to tidally influenced estuaries and its steady and unsteady solvers are suited to subcritical, supercritical and transitional flow regimes. It also has an integrated Muskingum-Cunge flow routing solver.

1D Steady State Solver

The steady state solver provides both direct steady-state and Pseudo-Timestepping methods to optimise run-time and enhance model stability. The main steady state solution method is called the Direct Method and is applicable to in-bank flow regimes.

It is a fast and very accurate solution method which requires very little initial data. It also incorporates an optional accurate supercritical and transcritical flow solver which has the capability of modelling hydraulic jumps and supercritical flow to a high degree of accuracy.

The Pseudo-Timestepping method uses a Preissmann 4-point scheme and is often used to develop initial conditions for unsteady runs or where flows are initially out of bank.

Although easy to apply to simple systems, the steady state solver includes a full range of hydraulic structures and is able to model complex looped channels and transcritical flows in steep rivers. This gives our software a much wider range of application when compared to other steady state modelling software.

1D Unsteady State Solver

The unsteady simulation solver employs the Preissmann implicit scheme to solve the equations for free surface flow, based on the Saint-Venant equations for flow in open channels. These are used in conjunction with the governing hydraulic equations for each hydraulic structure.

Flood Modeller Pro provides various features which have been specifically designed to improve model performance and management capabilities, during an unsteady simulation.

These equations are inevitably a combination of empirical and theoretical equations, many of them non-linear. The non-linear equations are first linearised and the solution to the linear form of the problem is then found.

In order to carry out unsteady simulations an estimate of the initial conditions (flow and stage) are required at every model node. This is most often obtained by carrying out a steady state run at the proposed start time.

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