ENH: Added new utility to create a box of isotropic turbulence

applications/utilities/preProcessing/createBoxTurb/createFields.H

@@ -0,0 +1,33 @@
+IOdictionary dict
+(
+    IOobject
+    (
+        "createBoxTurbDict",
+        runTime.constant(),
+        runTime,
+        IOobject::MUST_READ
+    )
+);
+
+// Extents in x, y, z directions
+const vector L(dict.get<vector>("L"));
+
+// Number of cells in x, y, z directions
+const Vector<label> N(dict.get<Vector<label>>("N"));
+
+// Wave number vs energy profile
+autoPtr<Function1<scalar>> Ek(Function1<scalar>::New("E", dict));
+
+// Number of modes
+const label nModes = dict.get<label>("nModes");
+
+// Mesh spacing in x, y and z directions
+const vector delta
+(
+    L.x()/scalar(N.x()),
+    L.y()/scalar(N.y()),
+    L.z()/scalar(N.z())
+);
+
+Random rndGen(1234);
+