The Wall node includes a set of boundary conditions describing fluid-flow conditions at stationary, moving, and leaking walls. For turbulent flow, the description may involve wall functions and/or asymptotic expressions for certain turbulence variables.

Select a Boundary condition for the wall.

If you also have a CFD Module, Heat Transfer Module or Microfluidics Module additional options become available as documented in the CFD Module User’s Guide, Heat Transfer Module User’s Guide or Microfluidics Module User’s Guide respectively.

No slip is the default boundary condition for a stationary solid wall for laminar flow (and SST, Low Re k-ε, Algebraic yPlus, L-VEL, and Spalart-Allmaras turbulence models). The condition prescribes u = 0; that is, the fluid at the wall is not moving.

The Slip option prescribes a no-penetration condition, u·n=0. It is implicitly assumed that there are no viscous effects at the slip wall and hence, no boundary layer develops. From a modeling point of view, this can be a reasonable approximation if the main effect of the wall is to prevent fluid from leaving the domain.

The Sliding wall boundary condition is appropriate if the wall behaves like a conveyor belt; that is, the surface is sliding in its tangential direction. A velocity is prescribed at the wall and the boundary itself does not have to actually move relative to the reference frame.

For an arbitrary wall movement, the condition u = uw may be prescribed. In this case, the components of the Velocity of moving wall uw should be specified.

This boundary condition may be used to simulate a wall where fluid is leaking into or leaving the domain with the velocity u = ul through a perforated wall. The components of the Fluid velocity ul on the leaking wall should be specified.Constraint Settings

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