diff --git a/CHANGELOG.md b/CHANGELOG.md
index bf0886afa57cf3cd298681584caacc7646f9a2aa..b59d2c66ce6cc457ff81701ccaadf5e3ad3e79bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,12 +24,16 @@ PDE solver, you may also now need to follow this distinction in the assembler an
use specialized assign and numeric operations in case your code allows for custom block types. If you are using the classes
from the `Dumux` namespace, no change should be necessary in user code in the majority of cases.
+- __Shallow water friction laws__: The friction laws after Manning and Nikuradse do no longer apply a limiter for the water depth. Previously, based on some application-specific assumption a roughness height was calculated that was added to the water depth. This
+height can now be provided as a argument to the respective friction law class constructors
+but defaults to `0.0`.
+
- __NewtonConvergenceWriter__: The convergence writer now takes three template arguments.
The new and last argument is the `ResidualType` (see above).
### Deprecated properties/classes/functions/files, to be removed after 3.7:
-- __AMGBackend__: `AMGBiCGSTABBackend` have been deprecated, use `AMGBiCGSTABIstlSolver` instead
+- __AMGBackend__: `AMGBiCGSTABBackend` have been deprecated, use `AMGBiCGSTABIstlSolver` instead
- __IstlSolverFactoryBackend__: `IstlSolverFactoryBackend` now require an additional parameter `LinearAlgebraTraits`
### New experimental features (possibly subject to backwards-incompatible changes in the future)
diff --git a/dumux/material/fluidmatrixinteractions/frictionlaws/frictionlaw.hh b/dumux/material/fluidmatrixinteractions/frictionlaws/frictionlaw.hh
index 6bb6c539d7b14712357aaa169d3696d559b5f33e..bfa7d79163d6d03b5e1cba0c5157ddfce07cb444 100644
--- a/dumux/material/fluidmatrixinteractions/frictionlaws/frictionlaw.hh
+++ b/dumux/material/fluidmatrixinteractions/frictionlaws/frictionlaw.hh
@@ -34,7 +34,8 @@ namespace Dumux {
* \ingroup Fluidmatrixinteractions
* \brief Implementation of the abstract base class for friction laws.
*
- * The LET mobility model is used to limit the friction for small water depths.
+ * A LET mobility model can be used to add an artificial water depth to
+ * limit the friction for small water depths.
*/
template <typename VolumeVariables >
@@ -58,9 +59,16 @@ public:
/*!
* \brief 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
+ * Compute a small artificial water depth that is added to the
+ * actual water depth to avoid extreme friction values which can
+ * occur for small water depths.
+ *
+ * The function is called with a roughness height, which can be
+ * seen as roughness height of the surface (e.g. grain size). For a
+ * zero roughnessHeight the artificial water depth will be zero.
+ *
+ * A water depth minUpperH (minUpperH = 2 * roughnessHeight) is
+ * defined for the limiting. Limiting is applied between both
* depths.
*
* ------------------------- minUpperH -----------
@@ -84,10 +92,14 @@ public:
* \param roughnessHeight roughness height of the representative structure (e.g. largest grain size).
* \param waterDepth water depth.
*/
- Scalar limitRoughH(const Scalar roughnessHeight, const Scalar waterDepth) const
+ Scalar limitRoughH(const Scalar roughnessHeight, const Scalar waterDepth, const Scalar eps=1.0e-12) const
{
using std::clamp;
+ // return zero if the roughness depth is near zero
+ if (roughnessHeight < eps) return 0.0;
+
+ // calculate the artificial water depth
const Scalar mobilityMax = 1.0; //!< maximal mobility
const Scalar minUpperH = roughnessHeight * 2.0;
diff --git a/dumux/material/fluidmatrixinteractions/frictionlaws/manning.hh b/dumux/material/fluidmatrixinteractions/frictionlaws/manning.hh
index 51e70977ee04a5b840c7d4d623c32425ded6fb57..477266fa0f1ef4cfef8f9f96829962721d2b8ee8 100644
--- a/dumux/material/fluidmatrixinteractions/frictionlaws/manning.hh
+++ b/dumux/material/fluidmatrixinteractions/frictionlaws/manning.hh
@@ -34,7 +34,8 @@ namespace Dumux {
* \ingroup Fluidmatrixinteractions
* \brief Implementation of the friction law after Manning.
*
- * The LET mobility model is used to limit the friction for small water depths.
+ * The LET mobility model is used to limit the friction for small water
+ * depths if a roughness height > 0.0 is provided (default roughnessHeight = 0.0).
*/
template <typename VolumeVariables>
@@ -46,10 +47,11 @@ public:
* \brief Constructor
*
* \param gravity Gravity constant (in m/s^2)
- * \param manningN Manning friction coefficient (in s/m^(1/3))
+ * \param manningN Manning friction coefficient (in s/m^(1/3)
+ * \param roughnessHeight roughness height for limiting (in m) default = 0.0
*/
- FrictionLawManning(const Scalar gravity, const Scalar manningN)
- : gravity_(gravity), manningN_(manningN) {}
+ FrictionLawManning(const Scalar gravity, const Scalar manningN, const Scalar roughnessHeight=0.0)
+ : gravity_(gravity), manningN_(manningN), roughnessHeight_(roughnessHeight) {}
/*!
* \brief Compute the bottom shear stress.
@@ -70,13 +72,12 @@ public:
Dune::FieldVector<Scalar, 2> shearStress(0.0);
- Scalar roughnessHeight = power(25.68/(1.0/manningN_), 6);
- roughnessHeight = this->limitRoughH(roughnessHeight, volVars.waterDepth());
+ const Scalar artificialWaterDepth = this->limitRoughH(roughnessHeight_, volVars.waterDepth());
// c has units of m^(1/2)/s so c^2 has units of m/s^2
- const Scalar c = pow(volVars.waterDepth() + roughnessHeight, 1.0/6.0) * 1.0/(manningN_);
+ const Scalar c = pow(volVars.waterDepth() + artificialWaterDepth, 1.0/6.0) * 1.0/(manningN_);
const Scalar uv = hypot(volVars.velocity(0), volVars.velocity(1));
-
const Scalar dimensionlessFactor = gravity_/(c*c);
+
shearStress[0] = dimensionlessFactor * volVars.velocity(0) * uv * volVars.density();
shearStress[1] = dimensionlessFactor * volVars.velocity(1) * uv * volVars.density();
@@ -86,6 +87,7 @@ public:
private:
Scalar gravity_;
Scalar manningN_;
+ Scalar roughnessHeight_;
};
} // end namespace Dumux
diff --git a/dumux/material/fluidmatrixinteractions/frictionlaws/nikuradse.hh b/dumux/material/fluidmatrixinteractions/frictionlaws/nikuradse.hh
index 258341e71642e650c136b8cb7cbfe68ca6d865de..2942fd4f68673a65b044b3602ecad5aadf3e180f 100644
--- a/dumux/material/fluidmatrixinteractions/frictionlaws/nikuradse.hh
+++ b/dumux/material/fluidmatrixinteractions/frictionlaws/nikuradse.hh
@@ -34,7 +34,8 @@ namespace Dumux {
* \ingroup Fluidmatrixinteractions
* \brief Implementation of the friction law after Nikuradse.
*
- * The LET mobility model is used to limit the friction for small water depths.
+ * The LET mobility model is used to limit the friction for small water
+ * depths if a roughness height > 0.0 is provided (default roughnessHeight = 0.0).
*/
template <typename VolumeVariables>
@@ -46,9 +47,10 @@ public:
* \brief Constructor
*
* \param ks Equivalent sand roughness (in m)
+ * \param roughnessHeight roughness height (in m) default = 0.0
*/
- FrictionLawNikuradse(const Scalar ks)
- : ks_(ks) {}
+ FrictionLawNikuradse(const Scalar ks, const Scalar roughnessHeight=0.0)
+ : ks_(ks), roughnessHeight_(roughnessHeight) {}
/*!
* \brief Compute the bottom shear stress.
@@ -69,10 +71,9 @@ public:
Dune::FieldVector<Scalar, 2> shearStress(0.0);
- Scalar roughnessHeight = ks_;
- roughnessHeight = this->limitRoughH(roughnessHeight, volVars.waterDepth());
+ const Scalar artificialWaterDepth = this->limitRoughH(roughnessHeight_, volVars.waterDepth());
const Scalar karmanConstant = 0.41; // Karman's constant is dimensionless
- const Scalar dimensionlessFactor = power(karmanConstant, 2)/power(log((12*(volVars.waterDepth() + roughnessHeight))/ks_), 2);
+ const Scalar dimensionlessFactor = power(karmanConstant, 2)/power(log((12*(volVars.waterDepth() + artificialWaterDepth))/ks_), 2);
const Scalar uv = hypot(volVars.velocity(0),volVars.velocity(1));
shearStress[0] = dimensionlessFactor * volVars.velocity(0) * uv * volVars.density();
@@ -83,6 +84,7 @@ public:
private:
Scalar ks_;
+ Scalar roughnessHeight_;
};
} // end namespace Dumux