anchor.diff:             end if 
           end if 
   
  -        call md_vel_flow_partial(solvent, dt, g)
  +        call md_vel(solvent, dt)
  +
           if (.not. fixed) then
              if (on_track) then
                 !only update in the direction of the flow
  
positive.code:      do k = 1, particles% Nmax
          s = particles% species(k)
          if (s <= 0) continue
          if ((particles% pos(1,k) > randomisation_length) .and. (particles% pos(1,k) < bufferlength)) then
             if (particles% pos(2,k) < edges(2)/2.d0) then
                bulk_change(s) = bulk_change(s) - 1
                particles% species(k) = 1
  
negative.code:   integer :: i, L(3),  n_threads
    integer :: j, k, m
    
    type(timer_t) :: flag_timer, change_timer, buffer_timer, varia, randomize_timer
    integer(HID_T) :: timers_group
  
    integer, allocatable :: rho_xy(:,:,:)
  