FEM EquationFlow

This equation calculate viscous fluid flows using the Navier-Stokes equations.

For info about the math of the equation, see the Elmer models manual, section Navier-Stokes Equations.

Usage

 * 1) After adding an Elmer solver as described here, select it in the tree view.
 * 2) Now either use the toolbar button [[Image:FEM_EquationFlow.svg|24px]] or the menu.
 * 3) Change the equation's solver settings or the general solver settings if necessary.

Solver Settings
For the general solver settings, see the Elmer solver settings.

The flow equation provides these special settings:

Constraint Information
The electrostatic equation takes the following constraints into account if they are set:


 * [[Image:FEM_ConstraintFlowVelocity.svg|32px]] Constraint flow velocity
 * [[Image:FEM_ConstraintInitialFlowVelocity.svg|32px]] Constraint initial flow velocity
 * [[Image:FEM_ConstraintInitialPressure.svg|32px]] Constraint initial pressure
 * [[Image:FEM_ConstraintPressure.svg|32px]] Constraint pressure

Note
Except for calculations in 2D, for all above constraints it is important that they act on a face or body. Constraints for 3D set to lines or vertices are not recognized by the Elmer solver.

Results
The results are the velocity in $$\rm m/s$$ and the pressure in $$\rm Pa$$. If there is no Constraint initial pressure and  Constraint pressure constraint given, the resulting pressure will be relative not absolute. Since a pressure must act on a face, absolute pressure results cannot be obtained in 2D simulations