diff --git a/swirl_dynamics/projects/weno_nn/utils.py b/swirl_dynamics/projects/weno_nn/utils.py
new file mode 100644
index 0000000..dcab283
--- /dev/null
+++ b/swirl_dynamics/projects/weno_nn/utils.py
@@ -0,0 +1,115 @@
+# Copyright 2024 The swirl_dynamics Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Several simple utilities."""
+
+from collections.abc import Callable
+from typing import Any, Literal
+
+import flax.linen as nn
+import jax
+from swirl_dynamics.lib.networks import rational_networks
+from swirl_dynamics.projects.weno_nn import weno_nn
+
+
+PyTree = Any
+Array = jax.Array
+
+
+def flat_dim(params: PyTree) -> int:
+  """Computes the total number of scalar elements in a `PyTree`.
+
+  Args:
+    params: PyTree containing the parameters/scalar values.
+
+  Returns:
+    Total number of scalars within all the leaves of the PyTree.
+  """
+  flat_params, _ = jax.tree_util.tree_flatten(params)
+  return sum([p.size for p in flat_params])
+
+
+def get_feature_func(
+    func_name: Literal[
+        'z_layer', 'rational', 'rational_descentered', 'delta_layer'
+    ]
+) -> Callable[[Array], Array] | None:
+  """Returns the feature function for the given function name.
+
+  Args:
+    func_name: Name of the function.
+
+  Returns:
+    The feature function for the given function name.
+  """
+
+  if func_name == 'z_layer':
+    func = weno_nn.weno_z_layer
+  elif func_name == 'rational':
+    func = weno_nn.FeaturesRationalLayer()
+  elif func_name == 'rational_descentered':
+    func = weno_nn.FeaturesRationalLayerDescentered()
+  elif func_name == 'delta_layer':
+    func = weno_nn.delta_layer
+  else:
+    func = None
+
+  return func
+
+
+def get_act_func(
+    func_name: Literal[
+        'relu',
+        'gelu',
+        'selu',
+        'rational',
+        'rational_unshared',
+        'swish',
+        'rational_act_fun',
+        'unshared_rational_act_fun',
+        'GeGLU',
+    ]
+) -> Callable[[Array], Array] | str | None:
+  """Returns the activation function for the given function name.
+
+  Args:
+    func_name: Name of the function.
+
+  Returns:
+    The activation function for the given function name, or the string for
+    defining the model inside the OmegaNN models.
+  """
+
+  if func_name == 'relu':
+    func = nn.relu
+  elif func_name == 'gelu':
+    func = nn.gelu
+  elif func_name == 'selu':
+    func = nn.selu
+  elif func_name == 'rational':
+    func = rational_networks.RationalLayer()
+  elif func_name == 'rational_unshared':
+    func = rational_networks.UnsharedRationalLayer()
+  elif func_name == 'swish':
+    func = nn.swish
+  elif func_name == 'rational_act_fun':
+    func = 'rational_act_fun'
+  elif func_name == 'unshared_rational_act_fun':
+    func = 'unshared_rational_act_fun'
+  elif func_name == 'GeGLU':
+    func = 'GeGLU'
+  else:
+    func = None
+
+  return func
diff --git a/swirl_dynamics/projects/weno_nn/weno_nn.py b/swirl_dynamics/projects/weno_nn/weno_nn.py
index c76d84a..55d82ae 100644
--- a/swirl_dynamics/projects/weno_nn/weno_nn.py
+++ b/swirl_dynamics/projects/weno_nn/weno_nn.py
@@ -351,16 +351,3 @@ def __call__(self, u_bar: Array, test: bool = False) -> Array:
       omega_out = eno_layer(omega_out, self.eno_layer_cutoff)
 
     return omega_out
-
-
-def flat_dim(params: PyTree) -> int:
-  """Computing the total number of scalar elements in a PyTree.
-
-  Args:
-    params: PyTree containing the parameters/scalar values.
-
-  Returns:
-    Total number of scalars within all the leaves of the PyTree.
-  """
-  flat_params, _ = jax.tree_util.tree_flatten(params)
-  return sum([p.size for p in flat_params])