Dumux::FrictionLawNikuradse< VolumeVariables > Class Template Reference

Implementation of the friction law after Nikuradse. More...

#include <dumux/material/fluidmatrixinteractions/frictionlaws/nikuradse.hh>

Inheritance diagram for Dumux::FrictionLawNikuradse< VolumeVariables >:

Description

template<typename VolumeVariables>
class Dumux::FrictionLawNikuradse< VolumeVariables >

Implementation of the friction law after Nikuradse.

The LET mobility model is used to limit the friction for small water depths.

Public Member Functions
	FrictionLawNikuradse (const Scalar ks)
	Constructor. More...
Dune::FieldVector< Scalar, 2 >	bottomShearStress (const VolumeVariables &volVars) const final
	Compute the bottom shear stress. More...
Scalar	limitRoughH (const Scalar roughnessHeight, const Scalar waterDepth) const
	Limit the friction for small water depth. More...

Constructor & Destructor Documentation

FrictionLawNikuradse()

template<typename VolumeVariables >

Dumux::FrictionLawNikuradse< VolumeVariables >::FrictionLawNikuradse ( const Scalar  ks )

inline

Constructor.

Parameters

ks	Equivalent sand roughness (in m)

Member Function Documentation

bottomShearStress()

template<typename VolumeVariables >

Dune::FieldVector< Scalar, 2 > Dumux::FrictionLawNikuradse< VolumeVariables >::bottomShearStress ( const VolumeVariables &  volVars ) const

inlinefinalvirtual

Compute the bottom shear stress.

Parameters

volVars

Volume variables

Compute the bottom shear stress due to bottom friction. The bottom shear stress is a projection of the shear stress tensor onto the river bed. It can therefore be represented by a (tangent) vector with two entries.

Returns

shear stress in N/m^2. First entry is the x-component, the second the y-component.

Implements Dumux::FrictionLaw< VolumeVariables >.

limitRoughH()

template<typename VolumeVariables >

Scalar Dumux::FrictionLaw< VolumeVariables >::limitRoughH ( const Scalar  roughnessHeight, const Scalar  waterDepth  ) const

inlineinherited

Limit the friction for small water depth.

We define a water depth minUpperH. If the water depth is smaller, we start to limit the friction. So the friction term gets not extreme large for small water depths.

----------------------— minUpperH --------—

---------------------—roughnessHeight ------------— /\ /\ roughness /grain\ ----------------------------—bottom ---------------— /////////////////////////////////////////////////

For the limiting the LET model is used, which is usually applied in the porous media flow to limit the permeability due to the saturation. It employs the three empirical parameters L, E and T, which describe the limiting curve (mobility).

auto mobility = (mobility_max * pow(sw,L))/(pow(sw,L) + E * pow(1.0-sw,T));

For the limitation of the roughness height L = 0.0, T = 2.0 and E = 1.0 are chosen. Therefore the calculation of the mobility is simplified significantly.

Parameters

roughnessHeight	roughness height of the representative structure (e.g. largest grain size).
waterDepth	water depth.

< maximal mobility

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The documentation for this class was generated from the following file:

• nikuradse.hh