FEM ConstraintFlowVelocity

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Fem-constraint-flow-velocity.svg FEM ConstraintFlowVelocity

Menu location
Model → Fluid constraints → Constraint flow velocity
Default shortcut
Introduced in version
See also
FEM tutorial


Applies a flow velocity boundary condition to a face in 3D or to an edge in 2D.


  1. Click on Fem-constraint-flow-velocity.svg or choose ModelFluid ConstraintsFem-constraint-flow-velocity.svg Constraint flow velocity from the top menu
  2. The task panel for constraint flow velocity appears
    FEM-constraint-flow-velocity task-panel.png
  3. Select the target Edges or Faces
  4. Click Add
  5. Untick "unspecified" to activate the necessary fields for edition
  6. Fill in the values in mm/s for the main cartesian components


  • Vector components that are ticked as "unspecified" will be interpolated by the selected solver.
    • Any vector that should be the result of the solver must be ticked as "unspecified".
  • If the target face or edge is not aligned with the main cartesian coordinate system, it is possible to tick "normal to boundary".
    • If "normal to boundary" is ticked, the normal vector to the selected edge or face is X and it will be oriented away from the mesh domain.
      • For example, if a flow of 20 mm/s of air must enter the domain, then after ticking "normal to boundary" the user will have to input -20 mm/s in the "velocity X" field.