SUBROUTINE lpm_extend_tails
!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE. See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see .
!
! Copyright 1997-2012 Leibniz University Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! ------------------
!
!
! Former revisions:
! -----------------
! $Id: lpm_extend_tails.f90 1037 2012-10-22 14:10:22Z raasch $
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 849 2012-03-15 10:35:09Z raasch
! initial revision (former part of advec_particles)
!
!
! Description:
! ------------
! Add the current particle positions to the particle tails.
!------------------------------------------------------------------------------!
USE control_parameters
USE particle_attributes
IMPLICIT NONE
INTEGER :: i, n, nn
REAL :: distance
distance = 0.0
DO n = 1, number_of_particles
nn = particles(n)%tail_id
IF ( nn /= 0 ) THEN
!
!-- Calculate the distance between the actual particle position and the
!-- next tailpoint
IF ( minimum_tailpoint_distance /= 0.0 ) THEN
distance = ( particle_tail_coordinates(1,1,nn) - &
particle_tail_coordinates(2,1,nn) )**2 + &
( particle_tail_coordinates(1,2,nn) - &
particle_tail_coordinates(2,2,nn) )**2 + &
( particle_tail_coordinates(1,3,nn) - &
particle_tail_coordinates(2,3,nn) )**2
ENDIF
!
!-- First, increase the index of all existings tailpoints by one
IF ( distance >= minimum_tailpoint_distance ) THEN
DO i = particles(n)%tailpoints, 1, -1
particle_tail_coordinates(i+1,:,nn) = &
particle_tail_coordinates(i,:,nn)
ENDDO
!
!-- Increase the counter which contains the number of tailpoints.
!-- This must always be smaller than the given maximum number of
!-- tailpoints because otherwise the index bounds of
!-- particle_tail_coordinates would be exceeded
IF ( particles(n)%tailpoints < maximum_number_of_tailpoints-1 ) &
THEN
particles(n)%tailpoints = particles(n)%tailpoints + 1
ENDIF
ENDIF
!
!-- In any case, store the new point at the beginning of the tail
particle_tail_coordinates(1,1,nn) = particles(n)%x
particle_tail_coordinates(1,2,nn) = particles(n)%y
particle_tail_coordinates(1,3,nn) = particles(n)%z
particle_tail_coordinates(1,4,nn) = particles(n)%class
!
!-- Increase the age of the tailpoints
IF ( minimum_tailpoint_distance /= 0.0 ) THEN
particle_tail_coordinates(2:particles(n)%tailpoints,5,nn) = &
particle_tail_coordinates(2:particles(n)%tailpoints,5,nn) + dt_3d
!
!-- Delete the last tailpoint, if it has exceeded its maximum age
IF ( particle_tail_coordinates(particles(n)%tailpoints,5,nn) > &
maximum_tailpoint_age ) THEN
particles(n)%tailpoints = particles(n)%tailpoints - 1
ENDIF
ENDIF
ENDIF
ENDDO
END SUBROUTINE lpm_extend_tails