From 57f44044b06ed0e49f1879655e4eee04374f3e73 Mon Sep 17 00:00:00 2001
From: Timo Koch <timo.koch@iws.uni-stuttgart.de>
Date: Sun, 3 Dec 2017 21:44:56 +0100
Subject: [PATCH] Implement DiffusivityConstantTortuosity that reads tortuosity
from command line
---
.../diffusivityconstanttortuosity.hh | 73 +++++++++++++++++++
1 file changed, 73 insertions(+)
create mode 100644 dumux/material/fluidmatrixinteractions/diffusivityconstanttortuosity.hh
diff --git a/dumux/material/fluidmatrixinteractions/diffusivityconstanttortuosity.hh b/dumux/material/fluidmatrixinteractions/diffusivityconstanttortuosity.hh
new file mode 100644
index 0000000000..730bc3d81e
--- /dev/null
+++ b/dumux/material/fluidmatrixinteractions/diffusivityconstanttortuosity.hh
@@ -0,0 +1,73 @@
+// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// vi: set et ts=4 sw=4 sts=4:
+/*****************************************************************************
+ * See the file COPYING for full copying permissions. *
+ * *
+ * This program is free software: you can redistribute it and/or modify *
+ * it under the terms of the GNU General Public License as published by *
+ * the Free Software Foundation, either version 2 of the License, or *
+ * (at your option) any later version. *
+ * *
+ * This program is distributed in the hope that it will be useful, *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
+ * GNU General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU General Public License *
+ * along with this program. If not, see <http://www.gnu.org/licenses/>. *
+ *****************************************************************************/
+/*!
+ * \file
+ *
+ * \brief Relation for the saturation-dependent effective diffusion coefficient
+ */
+#ifndef DIFFUSIVITY_CONSTANT_TORTUOSITY_HH
+#define DIFFUSIVITY_CONSTANT_TORTUOSITY_HH
+
+#include <dumux/common/parameters.hh>
+
+namespace Dumux
+{
+/*!
+ * \ingroup fluidmatrixinteractionslaws
+ *
+ * \brief Relation for the saturation-dependent effective diffusion coefficient
+ *
+ * The material law is:
+ * \f[
+ * D_\text{eff,pm} = \phi * S_w * \tau * D
+ * \f]
+ *
+ * with a constant tau.
+ *
+ * The default value is 0.5, empirically obtained in Carman 1937:
+ * <i>Fluid flow through granular beds</i> \cite carman1937
+ * Additionally, Bear 1972 \cite bear1972 mentions values 0.4 and in the
+ * range of 0.56 to 0.8.
+ */
+template<class Scalar>
+class DiffusivityConstantTortuosity
+{
+public:
+ /*!
+ * \brief Returns the effective diffusion coefficient \f$\mathrm{[m^2/s]}\f$ based
+ * on a constant tortuosity value
+ *
+ * \param porosity The porosity
+ * \param saturation The saturation of the wetting phase
+ * \param diffCoeff The diffusion coefficient of the phase in \f$\mathrm{[m^2/s]}\f$
+ */
+ static Scalar effectiveDiffusivity(const Scalar porosity,
+ const Scalar saturation,
+ const Scalar diffCoeff)
+
+ {
+ static const Scalar tau = getParam<Scalar>("SpatialParams.Tortuosity", 0.5);
+
+ return porosity * saturation * tau * diffCoeff;
+ }
+};
+
+} // end namespace Dumux
+
+#endif // DIFFUSIVITY_CONSTANT_TORTUOSITY_HH
--
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