diff --git a/src/modules/common/moduleRefParam.f90 b/src/modules/common/moduleRefParam.f90
index af85f36..e5e49e1 100644
--- a/src/modules/common/moduleRefParam.f90
+++ b/src/modules/common/moduleRefParam.f90
@@ -26,7 +26,8 @@ MODULE moduleRefParam
           sigmaVrel_ref = L_ref**2 * v_ref
 
         else
-            sigmaVrel_ref = pi*(r_ref+r_ref)**2*v_ref !reference cross section times velocity
+          ! Use the reference radius
+          sigmaVrel_ref = pi*(r_ref+r_ref)**2*v_ref
 
         end if