Translations:FEM ConstraintFlowVelocity/22/en

This code has the following syntax:
 * the prefix Variable specifies that the velocity is not a constant but a variable
 * the variable to calculate the velocity is Coordinate 2, meaning y
 * the velocity values are returned as Real (floating point value)
 * MATC is the prefix for the Elmer solver that the following code is a formula
 * tx is always the name of the variable in MATC formulas, no matter that tx in our case is actually y