DSMC Wind Tunnel Program DSWT
- The data is entered through interactive menus and comprises
the approximate number of megabytes to be used, the size of the
working section, the definition of the surface(s), and the specification
of the stream.
- The program sets the computational cells, the surface sampling
segments, and the time steps. It also determines whether an ideal
or real (with vibration and chemical reactions) gas is required,
and sets the initial uniform flow.
- The time steps are variable and are adaptively set to a set
fraction of the local mean collision time in order to meet one
of the two criteria for a good DSMC calculation. The sub cells
are also set adaptively and the program checks whether the number
of simulated molecules is sufficient to meet the other criterion
for a valid calculation. There are no numerical intabilities
associated with DSMC calculations.
- The calculation starts from zero time. The overall forces
on the surfaces are displayed and the user has many options for
the display of flow and surface properties.
- Flow samples are automatically reset during the unsteady
phase and time averaging is employed when (and if) the flow becomes
steady at large times. A progressive plot of the total number
of molecules provides an indication of the status of the flow.
- The units employed in the display may be switched between
metric and imperial. Alternatively a non-dimensional display
may be chosen.
- A left click of the mouse on a point in the flow contour
display generates a list of flow properties at the point. A right
click genates a flow streamline through the point.
- Text and bitmap files may be generated as required to document
and report on the flow.
The DSWT program consists of a new general
program DS2A with a special front-end and GUI for the wind tunnel
geometry. Similar extensions to the DS2A program could be made
for other geometries and classes of flow.