1!
2!     CalculiX - A 3-dimensional finite element program
3!     Copyright (C) 1998-2021 Guido Dhondt
4!
5!     This program is free software; you can redistribute it and/or
6!     modify it under the terms of the GNU General Public License as
7!     published by the Free Software Foundation(version 2);
8!
9!
10!     This program is distributed in the hope that it will be useful,
11!     but WITHOUT ANY WARRANTY; without even the implied warranty of
12!     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13!     GNU General Public License for more details.
14!
15!     You should have received a copy of the GNU General Public License
16!     along with this program; if not, write to the Free Software
17!     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18!
19!     This subroutines enables to calculate the reynolds number correction after:
20!     "Discharge coeffcients for incompressible non-cavitating flowthrough long orifices"
21!     A. Lichtarowicz, R.K duggins and E. Markland
22!     Journal  Mechanical Engineering Science , vol 7, No. 2, 1965
23!
24!     author: Yannick Muller
25!
26      subroutine cd_lichtarowicz(cd,cdu,reynolds,amod,bdh)
27!
28      implicit none
29!
30      real*8 cdu,reynolds,amod,bdh,eps,A1,cd_diff,cd0,cd
31!
32      cd0=cdu
33      cd_diff=1.d0
34!
35      do
36!
37         if(cd_diff.lt.1.d-3) exit
38!
39         cd=cd0
40         A1=20/(reynolds*dsqrt(1.d0-Amod**2))*(1.d0+2.25d0*bdh)
41         eps=(0.005d0*bdh)/(1.d0+7.5d0*(log10(0.00015d0*reynolds*
42     &        dsqrt(1.d0-Amod**2)/cd))**2)
43
44         cd=((-1/cdu+eps)+dsqrt((1/cdu-eps)**2.d0+4.d0*A1))/(2*A1)
45!
46         cd_diff=dabs(cd-cd0)
47!
48         cd0=cd
49!
50       enddo
51!
52         return
53         end
54