However, solving the 2D Saint Venant flow equations requires more computational power and thereby results in longer run times. The 2D Full Momentum computational method, often referred to as the Saint Venant equations for shallow flow, can account for turbulence and Coriolis effects, making it applicable to a wider set of conditions.

Quick estimate for using the Full Momentum computational methodĢD Saint Venant Full Momentum Computational Method.

Assess interior flooding (i.e., levee breach).

Compute rough global estimates (i.e., flood extents).

Fluid acceleration is monotonic and smooth (i.e., no waves).

Flow is mainly driven by gravity and friction.

The Diffusion Wave computational method can be used in the following situations: Most 2D modeling situations, such as flood modelling, can be accurately modeled using this solver, where inertial forces tend to dominate frictional and other forces. The 2D Diffusion Wave computational method is the default solver and allows the computations to run faster and with greater stability. HEC-RAS provides two methods for computing the flow field in a 2D mesh, both of which may be selected from the Unsteady Flow Computational Options dialog box available from the Analysis ribbon menu.īecause the user can easily switch between the 2D computational solvers, each solver can be tried for a given model to see if the 2D Saint Venant equations provides additional detail over the 2D Diffusion Wave equations. This article covers the basics of 2D flow modeling. To develop a 2D flow area model, an understanding of how the 2D flow model works is required.