diff --git a/sources/operators.F90 b/sources/operators.F90
index 5446291..4c528d2 100644
--- a/sources/operators.F90
+++ b/sources/operators.F90
@@ -198,13 +198,13 @@ module operators
     real(kind=8), dimension(:,:,:,:), intent(in)  :: u
     real(kind=8), dimension(:,:,:)  , intent(out) :: v
 
-! local arrays
-!
-    real(kind=8), dimension(:,:,:), allocatable :: w
-
 ! local variables
 !
     integer :: dir
+
+! local arrays
+!
+    real(kind=8), dimension(size(u,2), size(u,3), size(u,4)) :: w
 !
 !-------------------------------------------------------------------------------
 !
@@ -214,10 +214,6 @@ module operators
     call start_timer(imd)
 #endif /* PROFILE */
 
-! allocate temporary array
-!
-    allocate(w(size(u,2), size(u,3), size(u,4)))
-
 ! reset the output array
 !
     v(:,:,:) = 0.0d+00
@@ -236,10 +232,6 @@ module operators
 
     end do ! directions
 
-! deallocate temporary array
-!
-    deallocate(w)
-
 #ifdef PROFILE
 ! stop accounting time for the divergence operator calculation
 !
@@ -347,7 +339,7 @@ module operators
 
 ! local arrays
 !
-    real(kind=8), dimension(:,:,:), allocatable :: w
+    real(kind=8), dimension(size(u,2), size(u,3), size(u,4)) :: w
 !
 !-------------------------------------------------------------------------------
 !
@@ -357,10 +349,6 @@ module operators
     call start_timer(imc)
 #endif /* PROFILE */
 
-! allocate temporary array
-!
-    allocate(w(size(u,2), size(u,3), size(u,4)))
-
 ! === calculate Vx component ===
 !
 ! contribution from the Y derivative of Uz
@@ -427,10 +415,6 @@ module operators
 !
     v(3,:,:,:) = v(3,:,:,:) - w(:,:,:)
 
-! deallocate temporary array
-!
-    deallocate(w)
-
 #ifdef PROFILE
 ! stop accounting time for the rotation operator calculation
 !
@@ -472,7 +456,7 @@ module operators
 
 ! local arrays
 !
-    real(kind=8), dimension(:,:,:), allocatable :: w
+    real(kind=8), dimension(size(u,1), size(u,2), size(u,3)) :: w
 !
 !-------------------------------------------------------------------------------
 !
@@ -482,10 +466,6 @@ module operators
     call start_timer(iml)
 #endif /* PROFILE */
 
-! allocate temporary array
-!
-    allocate(w(size(u,1), size(u,2), size(u,3)))
-
 ! calculate the second derivative of U along the X direction
 !
     call derivative_2nd(1, dh(1), u(:,:,:), w(:,:,:))
@@ -512,10 +492,6 @@ module operators
     v(:,:,:) = v(:,:,:) + w(:,:,:)
 #endif /* NDIMS == 3 */
 
-! deallocate temporary array
-!
-    deallocate(w)
-
 #ifdef PROFILE
 ! stop accounting time for the laplace operator calculation
 !