Setting Velocity and Transport Values

These commands are used within shape commands for grid-based boundary conditions to set velocity, temperature, and/or concentration boundary conditions.

Velocity Conditions

The scripte Velocity command sets velocity conditions to all nodes with the shape command that encloses it:

Velocity (dir),(style),<(value)>,<(time)>

In XML files, the command is:

<DisBC dir='(dir)' style='(style)' vel='(value)' time='(time)' function='(function)' id='(id)'/>

where

• (dir) is 1, 2, or 3 to specify the velocity direction as in the x, y, or z direction (In script files, (dir) can be x, y, or z or can be R or Z if axisymmetric). You can also set velocity in a direction that is not along an axis. For details see help on skewed velocity conditions
• (style) specifies the style of the applied velocity. Each velocity depends on two parameters specified by arguments (value) and (time). If either argument is not supplied, they are set to zero. The styles are described below.
• (function)
• (id)

Boundary Condition Styles

The possible boundary condition styles are defined below. In script files, the style can be set by name or number; in XML files, the style must be set by number:

• constant (or 1) - the applied boundary conditions is set to the constant (value) and it is applied for times after (time).
• linear - the applied boundary condition is       [math]\displaystyle{ BC = (value)(t-(time)) }[/math] is arg1 * (time-arg2) where time is the current time; the velocity is applied for times after arg2. (arg1 is in mm/sec/ms and arg2 is in ms).
• "sine" - the applied velocity is arg1 * sin(arg2*time) where time is the current time; the velocity is applied for all times. (arg1 is in mm/sec and arg2 is in 1/ms).
• "cosine" - the applied velocity is arg1 * cos(arg2*time) where time is the current time; the velocity is applied for all times. (arg1 is in mm/sec and arg2 is in 1/ms).
• "function" - the applied velocity is determined by a <a href="function.html">user-defined function</a> of time (t in ms), nodal point position (x, y, and z in mm), and/or of current clockwise particle rotation angle (q in radians, 2D only), entered as quoted text in #3 (arg1). The function should evaluate to the desired velocity in mm/s. If arg2 is supplied, the velocity starts at time arg2 (in ms) and the function is evaluated at [t-arg2] (in ms).

Skewed Velocity Conditions

Temperature Conditions

Concentration Conditions