diff --git a/olaflow/processing/olaflow.py b/olaflow/processing/olaflow.py
new file mode 100644
index 0000000..520289b
--- /dev/null
+++ b/olaflow/processing/olaflow.py
@@ -0,0 +1,38 @@
+import re
+
+from fluidfoam import readof
+
+
+class OFModel:
+    def __init__(self, root):
+        self._root = root
+
+    def read_mesh(self):
+        self._x, self._y, self._z = readof.readmesh(str(self._root))
+
+    def write_field(self, field, values):
+        with open(self._root.joinpath("0", field), "r") as aw_file:
+            aw_raw = aw_file.read()
+
+        with open(self._root.joinpath("0", field), "w") as aw_file:
+            aw_file.write(
+                re.sub(
+                    r"(?<=\(\n).*?(?=\n\))",
+                    "\n".join(values.astype(str)),
+                    aw_raw,
+                    count=1,
+                    flags=re.S,
+                )
+            )
+
+    @property
+    def x(self):
+        return self._x
+
+    @property
+    def y(self):
+        return self._y
+
+    @property
+    def z(self):
+        return self._z
diff --git a/olaflow/processing/sws_ola.py b/olaflow/processing/sws_ola.py
index f0083e2..578d92c 100644
--- a/olaflow/processing/sws_ola.py
+++ b/olaflow/processing/sws_ola.py
@@ -2,13 +2,12 @@ import argparse
 import configparser
 import logging
 import pathlib
-import re
 
-import matplotlib.pyplot as plt
 import numpy as np
-from fluidfoam import readof
 from scipy import interpolate
 
+from .olaflow import OFModel
+
 parser = argparse.ArgumentParser(
     description="Convert swash output to olaFlow input"
 )
@@ -28,20 +27,10 @@ sws = np.load(sws_out.joinpath("sws.npz"))
 x, t = sws["x"], sws["t"]
 
 olaflow_root = pathlib.Path(config.get("olaflow", "root"))
-of_x, of_y, of_z = mesh = readof.readmesh(str(olaflow_root))
+model = OFModel(olaflow_root)
+model.read_mesh()
 
 watl = interpolate.interp1d(x, sws["watl"][680])
+alpha_water = np.where(model.z < watl(model.x), 1, 0)
 
-with open(olaflow_root.joinpath("0", "alpha.water"), "r") as aw_file:
-    aw_raw = aw_file.read()
-
-with open(olaflow_root.joinpath("0", "alpha.water"), "w") as aw_file:
-    aw_file.write(
-        re.sub(
-            r"(?<=\(\n).*?(?=\n\))",
-            "\n".join(map(str, alpha_water)),
-            aw_raw,
-            count=1,
-            flags=re.S,
-        )
-    )
+model.write_field("alpha.water", alpha_water)