/// <summary>
/// Use the specified fields to calculate the next set of PrognosticFields according to the shallow fluid model
/// equations.
/// </summary>
/// <param name="fields"></param>
/// <param name="oldFields"></param>
/// <param name="olderFields"></param>
/// <returns></returns>
public PrognosticFields Update(PrognosticFields fields, PrognosticFields oldFields = null, PrognosticFields olderFields = null)
{
var derivativeOfHeight = DerivativeOfHeight(fields.Velocity, fields.Height);
var derivativeOfVelocity = DerivativeOfVelocity(fields.Velocity, fields.Height);
// If oldFields & olderFields are defined, use all three to step the simulation forward. Otherwise, use the
// less-accurate Euler timestepping method and only the most recent set of fields.
ScalarField <Face> height;
VectorField <Vertex> velocity;
if (oldFields != null && olderFields != null)
{
height = NumericalDerivatives.AdamsBashforth(_options.Timestep, fields.Height, derivativeOfHeight, oldFields.DerivativeOfHeight, olderFields.DerivativeOfHeight);
velocity = NumericalDerivatives.AdamsBashforth(_options.Timestep, fields.Velocity, derivativeOfVelocity, oldFields.DerivativeOfVelocity, olderFields.DerivativeOfVelocity);
}
else
{
height = NumericalDerivatives.Euler(_options.Timestep, fields.Height, derivativeOfHeight);
velocity = NumericalDerivatives.Euler(_options.Timestep, fields.Velocity, derivativeOfVelocity);
}
var newFields = new PrognosticFields
{
DerivativeOfHeight = derivativeOfHeight,
DerivativeOfVelocity = derivativeOfVelocity,
Height = height,
Velocity = velocity
};
return(newFields);
}
/// <summary>
/// Step the simulation forward.
/// </summary>
public void StepSimulation()
{
var oldestFields = _olderFields;
_olderFields = _oldFields;
_oldFields = CurrentFields;
CurrentFields = _fieldUpdater.Update(_oldFields, _olderFields, oldestFields);
}
/// <summary>
/// Reset the simulation to the set of fields it was created with.
/// </summary>
public void Reset()
{
_olderFields = null;
_oldFields = null;
CurrentFields = _initialFields;
}
/// <summary>
/// Creates a simulation on the given surface using the given initial fields & options.
/// </summary>
/// <param name="surface"></param>
/// <param name="initialFields"></param>
/// <param name="options"></param>
public SimulationRunner(IPolyhedron surface, PrognosticFields initialFields, IModelParameters options)
{
_fieldUpdater = new PrognosticFieldsUpdater(surface, options);
_initialFields = initialFields;
CurrentFields = initialFields;
}