SMS:FESWMS Material Properties

Material properties include roughness, turbulence, and wind/wave parameters.

Roughness Parameters

The roughness helps determine the energy losses as water flows over elements. Each material includes roughness information.

• Manning n values (n1, n2, depth1, depth2)

The primary roughness property is the manning n value associated with the element. The manning n value can vary with depth by specifying n values at two depths. The n1 value is used below depth1. The n2 value is used above depth2. Between depth1 and depth2 the n value is linearly interpolated.

• Wall roughness

The wall roughness is used on the edge of the model domain. Wall roughness is ignored unless the model is using semi-slip boundaries.

• Soil Liners

FESWMS can be used with materials representing a soil liner. To use a liner, turn on the linear critical shear stress and set the value. When using a liner n1, n2, depth1, and depth2 are ignored.

• Pressure flow

It is required to toggle on "potential pressure flow" with all materials that are assigned to elements with a ceiling elevation. If pressure flow is enabled, the deck roughness is the manning value for the bridge deck. Otherwise deck roughness is ignored.

• Chezy

Chezy values are an alternative to using Manning n values for roughness. You must turn on chezy in the model parameters to use this value.

• Bed critical shear stress

The bed critical shear stress is used to compute clear water scour.

Turbulence Parameters

Turbulence parameters are used to control the energy lost in turbulence.

• Vo – Base eddy viscosity in Length^2/second
• Cu1, Cu2 – Turbulence model coefficients used to modify base eddy viscosity
• Eddy diffusivity – used to modify base eddy viscosity and is related to the amount of curves in the channel
• Storativity depth – The global storativity depth (specified in the model parameters) can be overriden on a material level by entering a non-zero value.