Add recipe for contact angles

prehner · prehner · commit ca2ddd724445 · 2026-01-25T16:50:33.000+01:00
diff --git a/docs/recipes/index.md b/docs/recipes/index.md
@@ -24,4 +24,5 @@ If you are looking for tutorials with explanations, see the [tutorials](/tutoria
 
    recipes_surface_tension_pure
    recipes_surface_tension_diagram_pure
+   recipes_contact_angle
 ```
diff --git a/docs/recipes/recipes_contact_angle.ipynb b/docs/recipes/recipes_contact_angle.ipynb
@@ -0,0 +1,91 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "a22a5252",
+   "metadata": {},
+   "source": [
+    "# Calculation of contact angles with cDFT"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "7fcfe24b",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import feos\n",
+    "import si_units as si\n",
+    "import numpy as np\n",
+    "\n",
+    "# set up fluid model\n",
+    "parameters = feos.Parameters.from_json([\"methanol\"], \"../../parameters/pcsaft/esper2023.json\")\n",
+    "functional = feos.HelmholtzEnergyFunctional.pcsaft(parameters)\n",
+    "\n",
+    "# set up surface\n",
+    "ext_pot = feos.ExternalPotential.LJ93(sigma_ss=3.0, epsilon_k_ss=120.0, rho_s=0.08)\n",
+    "pore = feos.Pore1D(feos.Geometry.Cartesian, 50*si.ANGSTROM, ext_pot)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "70ee72e5",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/latex": [
+       "$31.99°$"
+      ],
+      "text/plain": [
+       "31.990466526671963°"
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# calculate the density profiles of the vapor and the liquid states\n",
+    "vle = feos.PhaseEquilibrium.pure(functional, 350 * si.KELVIN)\n",
+    "vapor_profile = pore.initialize(vle.vapor).solve()\n",
+    "liquid_profile = pore.initialize(vle.liquid).solve()\n",
+    "\n",
+    "# calculate the solid/fluid interfacial tensions\n",
+    "gamma_sl = liquid_profile.interfacial_tension / si.ANGSTROM**2\n",
+    "gamma_sv = vapor_profile.interfacial_tension / si.ANGSTROM**2\n",
+    "\n",
+    "# calculate the vapor/liquid interfacial tension\n",
+    "vle_profile = feos.PlanarInterface.from_pdgt(vle, 2048).solve()\n",
+    "gamma_vl = vle_profile.surface_tension\n",
+    "\n",
+    "# calculate the contact angle from Young's equation\n",
+    "np.acos((gamma_sv-gamma_sl)/gamma_vl)*si.RADIANS"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "feos",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.14.0"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}
