Species Time Integration#
Species Time Integration= {model_name} <species>
Description / Usage#
Sharp gradients are often a feature of convective-diffusive computations involving species. Traditional Galerkin time integration is not optimal under these circumstances. This optional card is used to change the species time integration scheme to be different from the global time integration. Each species equation can use a different time integration. The new time integration schemes are based upon a Taylor-Galerkin formulation which has better behavior when sharp fronts are present.
Following are the {model_name} options for species time integration, each of which requires only a species designation to which the model should be applied:
STANDARD |
the input deck formulation, i.e., the global time integration scheme; this is the default.
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TAYLOR_GALERKIN |
an implicit or semi-implicit Taylor-Galerkin time integration scheme
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TAYLOR_GALERKIN_EXP |
An explicit Taylor-Galerkin time integration scheme
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Examples#
The following sample input card invokes the explicit Taylor-Galerkin time integration of the species equation.
Species Time Integration = TAYLOR_GALERKIN_EXP 0
Technical Discussion#
The Taylor-Galerkin schemes are designed for advection dominated problems with sharp fronts where rigorous mass conservation is important.
TAYLOR_GALERKIN uses an implicit or semi-implicit form of the Taylor- Galerkin time integrals depending on what is chosen in the input deck.
TAYLOR_GALERKIN_EXP uses an explicit form of the equations and is favored for volume-of-fluid simulations where the diffusive character of the implicit solver creates mass balance errors. The drawback of explicit time integration methods is that the time step used is governed by the Courant limit and must be quite small for stability.
References#
No References.