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 >	shearStress (const VolumeVariables &volVars) const final
	Compute the 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 [m]

Member Function Documentation

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 friciton. So the friciton term get's 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 paramaters 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 choosen. Therefore the calculation of the mobility is simplified significantly.

Parameters

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

< maximal mobility

shearStress()

template<typename VolumeVariables >

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

inlinefinalvirtual

Compute the shear stress.

Parameters

volVars

Volume variables

Compute the shear stress due to friction. The shear stress is not a tensor as know from contiuums mechanics, but a force projected on an area. Therefore it is a vector with two entries.

Returns

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

Implements Dumux::FrictionLaw< VolumeVariables >.

---

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

• nikuradse.hh