This tank sloshing example demonstrates the application of a simple user-defined gravity subroutine to free surface flow in a closed container. A sinusoidal variation of gravity is applied through UGRAVITY to force water in the tank to slosh back and forth in time. Potential applications of this type of study are applicable to the automotive industry (fuel tank sloshing), aerospace (tank sloshing in air vehicles and in microgravity environments), and civil engineering (earthquake studies). 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 box with a moving wall is used to demonstrate user defined moving grid. The UGRID subroutine supports both structured and unstructured grids. This routine is called on for each zone where user defined grid motion is specified 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.

In this tutorial, a custom Sawtooth Velocity Profile is specified using the user subroutine UBOUND. This routine is called on a face by face basis for each bc record. 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 custom initial condition (for example to start with a good approximate solution that would accelerate convergence) could be set using the user subroutine UINIT. In this example, the initial velocity is set to be the square of the x-coordinate. This routine is called for each variable in each volume condition requested in the INITIAL CONDITIONS section of the 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.

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, a custom Parabolic Velocity Profile is specified using the user subroutine UBOUND. This routine is called on a face by face basis for each bc record.

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.