my fix

tex/reynold.tex

@@ -16,5 +16,7 @@ Therefore
   \bar u = \SI{0.2}{\metre\per\second} \quad \text{for } \Rey = 20 \\
   \bar u = \SI{1}{\metre\per\second} \quad \text{for } \Rey = 100
 \end{align*}
-This can be changed the inlet velocity computation where a variable is used that is set in the file |scale|.
+This mean velocity needs to be changed in |0/U| in the code.
+It is not used if it lays in |system/codeDict|. (Ignored without error message or warning.)
+The mean velocity cannot be moved to |scale| as a variable because then the C++ code resuts in an error.
 \docEnd