Application Note: Taking Charge
How often have we been in situations where we wish we were in charge? It makes things so easy when we can make the decision to get what we want when we want it. Taking charge can be fun and satisfying. Unfortunately, the opposite situation of not being able to make decision can be frustrating and unsatisfying.
Commercial software is generally designed to make things easy for the user, but this often means that many decision have been made by the developers on behalf of the users. When a simulation seems to be producing wrong results, or you want you output to be in a special form, or perhaps you want output that is not of a standard kind, it would be great if you could simply take change and get what you want with a minimum of fuss.
Well, you can do this in FLOW-3D by enlisting the aid of those "secret agents," the scalar variables. Scalars are usually passive and do not affect a flow unless they have been programmed to do so. Their advantage for helping you take charge is that, when you request one or more scalar arrays to be initialized at the beginning of a computation, their values will then be automatically sent to the output data file where they are available for plotting and printing.
Taking charge means that you can put just about any numerical quantities into a scalar array. Computed data, for instance, could be combined from several sources, or transformed b translation and magnification, or even filtered. For debugging purposes, intermediate results from custom algorithms could be placed in scalar arrays. Scalar arrays make it easy to produced special purposed, derived data. An example of the latter is shown in the accompanying plots of vorticity in the oscillating wake (vortex street) computed behind a circular cylinder at high Reynolds number. The plot shows the vorticity in the wake of the cylinder.
Taking charge is a good feeling. Sign up some scalar agents in FLOW-3D to give yourself the feeling of control.