The LES Smagorinsky Interface
The LES Smagorinsky (spf) interface () is used for simulating single-phase flows at high Reynolds numbers by resolving the larger three-dimensional unsteady eddies and modeling the effect of the smaller eddies. The physics interface is currently only suitable for incompressible flows.
The equations solved by the LES Smagorinsky interface are the continuity equation for conservation of mass and the Navier-Stokes equation, augmented by a turbulent viscosity term. The modeled term is inconsistent, which means that it does not vanish for a fully resolved flow.
The LES Smagorinsky interface should only be used for three-dimensional, time-dependent analyses. The main feature is Fluid Properties, which adds the Navier-Stokes and continuity equations, and provides an interface for defining the fluid material and its properties. When this physics interface is added, the following default nodes are also added in the Model Builder: Fluid Properties, Initial Values, and Wall.
Except where included below, see The Laminar Flow Interface for all the other settings.
Turbulence
A different LES model can be selected under Turbulence model. A RANS turbulence model can be selected by changing the Turbulence model type to RANS. Laminar or creeping flow may be simulated by changing the Turbulence model type to None.
The Turbulence model property disables the Neglect inertial term (Stokes flow) check box and Enable porous media domains check box.
Use dynamic subgrid timescale
Enable this check-box to use the time-derivative from the previous time-step to estimate temporal changes in the unresolved scales.
Edit LES Model Parameters
Turbulence model parameters are optimized to fit as many flow types as possible, but for some special cases, better performance can be obtained by tuning the model parameters.
For this physics interface the Smagorinsky parameter is .
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
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The Laminar Flow Interface
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Theory for the Large Eddy Simulation Interfaces
Domain, Boundary, Pair, and Point Nodes for Single-Phase Flow
The following nodes, listed in alphabetical order, are available from the Physics ribbon toolbar (Windows users), Physics context menu (Mac or Linux users), or by right-clicking to access the context menu (all users).
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Boundary Stress
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Fan
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Flow Continuity
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Fluid Properties
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Generate New Turbulence Model Interface
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Grille
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Gravity
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Initial Values
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Inlet
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Interior Fan
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Interior Wall
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Line Mass Source1
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Open Boundary
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Outlet
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Periodic Flow Condition
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Point Mass Source1
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Pressure Point Constraint
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Screen
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Stationary Free Surface
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Symmetry
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Vacuum Pump
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Volume Force
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Wall
1 A feature that may require an additional license
For 2D axisymmetric components, COMSOL Multiphysics takes the axial symmetry boundaries (at r = 0) into account and adds an Axial Symmetry node that is valid on the axial symmetry boundaries only.
In the COMSOL Multiphysics Reference Manual, see Table 2-3 for links to common sections and Table 2-4 to common feature nodes. You can also search for information: press F1 to open the Help window or Ctrl+F1 to open the Documentation window.