diff --git a/sources/user_problem.F90 b/sources/user_problem.F90
index 98e4b4b..263376b 100644
--- a/sources/user_problem.F90
+++ b/sources/user_problem.F90
@@ -57,6 +57,7 @@ module user_problem
   real(kind=8), save :: ycut  = 1.00d+99
   real(kind=8), save :: xdec  = 1.00d+00
   real(kind=8), save :: ydec  = 1.00d+00
+  real(kind=8), save :: yref  = 1.00d-01
 
   real(kind=8), dimension(:), allocatable :: kx, ky, kz, ux, uy, uz, ph
 
@@ -98,6 +99,7 @@ module user_problem
     use helpers    , only : print_section, print_parameter, print_message
     use mesh       , only : setup_problem
     use parameters , only : get_parameter
+    use refinement , only : user_criterion
     use random     , only : reset_seeds, randuni, randsym
 
     implicit none
@@ -193,6 +195,7 @@ module user_problem
    call get_parameter("ycut", ycut)
    call get_parameter("xdec", xdec)
    call get_parameter("ydec", ydec)
+   call get_parameter("yref", yref)
 
 ! choose the perturbation type
 !
@@ -406,10 +409,12 @@ module user_problem
       call print_parameter(verbose, '(*) ycut'      , ycut)
       call print_parameter(verbose, '(*) ydec'      , ydec)
     end if
+    call print_parameter(verbose, '(*) yref'      , yref)
 
     setup_problem     => setup_user_problem
     custom_boundary_x => user_boundary_x
     custom_boundary_y => user_boundary_y
+    user_criterion    => refinement_criterion
 
     status = 0
 
@@ -1245,6 +1250,42 @@ module user_problem
 !-------------------------------------------------------------------------------
 !
   end subroutine user_statistics
+!
+!===============================================================================
+!
+! function REFINEMENT_CRITERION:
+! -----------------------------
+!
+!   Function finds the maximum values of the vorticity magnitude
+!   for the current data block.
+!
+!   Arguments:
+!
+!     pdata - pointer to the data block for which error is calculated;
+!
+!===============================================================================
+!
+  function refinement_criterion(pdata) result(crit)
+
+    use blocks, only : block_data
+
+    implicit none
+
+    type(block_data), pointer, intent(in) :: pdata
+
+    real(kind=4)  :: crit
+
+!-------------------------------------------------------------------------------
+!
+    crit = 0.0e+00
+
+    if (min(abs(pdata%meta%ymin), abs(pdata%meta%ymax)) <= yref) crit = 1.0e+00
+
+    return
+
+!-------------------------------------------------------------------------------
+!
+  end function refinement_criterion
 
 !===============================================================================
 !