The Viscoelastic Flow Interface
The Viscoelastic Flow (vef) interface () is used for simulating single-phase flows of viscoelastic fluids. The physics interface is only suitable for incompressible flows.
The equations solved by the Viscoelastic Flow interface are the continuity equation for conservation of mass, the Navier-Stokes equations, augmented by an elastic stress tensor term, and a constitutive equation that defines the extra elastic stress contribution.
The Viscoelastic Flow interface is available for 2D and 3D stationary and time-dependent analyses. The main feature is Fluid Properties, which adds the Navier-Stokes equations, continuity equations, and the constitutive relations between the extra elastic stress term and the velocity gradient. The Fluid Properties feature provides an interface for defining the fluid material and its properties. Viscoelastic, Newtonian, and Inelastic non-Newtonian constitutive relations are available.
When this physics interface is added, the following default nodes are also added in the Model Builder:
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 Fluid Properties
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 Initial Values
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 Wall
Except where included below, see The Laminar Flow Interface for all the other settings.
Dependent Variables
The following dependent variables (fields) are defined for this physics interface:
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 Velocity field u and its components
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 Pressure p
If the Viscoelastic constitutive relation is selected, the Fluid Properties node also adds as variables the components of the elastic stress tensor.