To display the Constraint Settings section in Constraint nodes, click the Show button () on the Model Builder tool bar and select Advanced Physics Options.
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Normal-direction constraints on a moving mesh, where the mesh motion is part of the problem. These conditions are of the type n · u − r = 0 where n = n(x) is the boundary normal, u is a vector field (displacements or velocity), and x is the mesh coordinate vector. Symmetric constraints give constraint forces not only on the equations for u but also on the equations for x, which typically are not wanted.
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Wall boundary conditions for turbulent fluid flow. For the k-ε turbulence model, this condition is of the type k − r( ε ), −n · ∇ε, where r is a given function. Bidirectional constraints for the first relation imply that the second relation cannot hold.
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