A solution of steady state temperature in simple, 2D, rectangular solid demonstrates the use of a variable time step size. The left and right walls are isothermal (300° C and 500° C, respectively), while the top and bottom walls are adiabatic (symmetry and wall, respectively). The initial temperature in the volume is set to 300° C. The time step starts out relatively small (0.5 seconds) and is increased at a rate of time_step = 1.2 * time_step. Once the time step becomes very large (greater than 200, in this case) the time step remains constant. The variation of time step size with time is written to an external file. User subroutines are built as Dynamic Link Libraries (DLL files for Windows) or shared objects (.so files for UNIX platforms). The shared libraries are then linked with CFD-ACE-SOLVER such that a two way communication between the solver and the user defined input is established.

In this tutorial, the application of a time dependent boundary condition is demonstrated by applying a sinusoidal motion to a wall. The UBOUND_NODAL subroutine is called on a node-by-node basis for each boundary condition where structural bc is specified as user defined in CFD-ACE-GUI. User subroutines are built as Dynamic Link Libraries (DLL files for Windows) or shared objects (.so files for UNIX platforms). The shared libraries are then linked with CFD-ACE-SOLVER such that a two way communication between the solver and the user defined input is established.

A simple, 2D serpentine duct is used to demonstrate the effects of setting laminar viscosity equal to a function of the x-direction velocity gradient. The viscosity increases with the gradient and thus is a "shear-thickening" fluid. This example uses UOUT to obtain the solution gradients, then UVISC contains the code to calculate and set the viscosity.

In this tutorial, the free surface (VOF) and heat transfer features of CFD-ACE+ are used to model the thermal expansion of a fluid.