11.7 Session file configuration: Adaptive polynomial order

An adaptive polynomial order procedure is available for 2D and Quasi-3D simulations. This procedure consists of the following steps:

It is important to note that restarting the simulation after the refinement can be an expensive operation (in a typical case 200 times the cost of a single time step). Therefore, the number of steps between successive refinements needs to be carefully chosen, since if this value is too low the procedure becomes inefficient, while if it is too high the refinement might not capture accurately structures that are convected by the flow.

11.7.1 Solver Info

The use of the adaptive polynomial order procedure is enforced through the definition of the Driver which has to be Adaptive.

11.7.2 Parameters

The following parameters can be specified in the PARAMETERS section of the session file:

11.7.3 Functions

Spatially varying tolerances can be specified by defining the functions AdaptiveLowerinModes and/or AdaptiveUpperTolerance. In this case, the tolerance in an element is taken as the average of the function in the quadrature points of the element. If these functions are defined, the values set for the tolerances in the PARAMETERS section are ignored.

11.7.4 Restarting the simulation

The simulation can be restarted using the final distribution of polynomial orders obtained from the adaptive procedure by setting the expansions as

2  <F FILE="restartfile.fld" /> 

note that this will only affect the polynomial order. The initial condition still needs to be set correctly, and does not need to come from the same file used for the expansions.