About the Import of Initial Conditions

You can import the results of one analysis case to use as the initial conditions for another analysis case.

See Also
Importing Results as Initial Conditions

Importing results as initial conditions can enable you to define the initial state of the current analysis case faster. When you import results, you can import the current set of results from an analysis case or a previous set, and you can import results from the end of the analysis case or from the end of one of its steps. You can also import values for all field output variables in the source analysis case or from a selected subset of them.

Importing results as initial conditions offers the following advantages as you set up a simulation:

  • Using imported results can reduce simulation time in the long run. You can perform a simulation with a coarse mesh first, then refine its mesh and perform a new simulation with the finer mesh using the import capability. In general, starting with better initial conditions reduces the total number of iterations to achieve convergence, and imported results provide better initial conditions than a uniform initial value. The simulation time saved from reducing the number of iterations from the fine case can exceed the extra cost of running the coarse simulation. For example, in an analysis where the energy field is progressing mostly by diffusion, the simulation can require many iterations to reach the final distribution. By providing a good initial solution from a converged coarse solution, the solver can converge to a solution after relatively few iterations.
  • Converging on an initial solution first can help you avoid initial instabilities that can cause convergence problems later in the simulation. For example, when running with the compressible flow solver, the initial solution can be critical. You can run some iterations with the incompressible solver to generate results that you can use as approximated initial conditions, and then run the compressible solver simulation using these imported initial conditions.
  • Importing initial conditions can make it easier to perform a parameterized simulation in which you study the effects of changing a single variable. You can reduce the overall computation time by starting each of the simulations from a previous converged solution.

The results data that you import and the target simulation where you use them must reside in the same location. Both simulations must be available locally or both must be on the cloud.