/[MITgcm]/MITgcm/pkg/generic_advdiff/gad_plm_fun.F
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Contents of /MITgcm/pkg/generic_advdiff/gad_plm_fun.F

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Revision 1.1 - (show annotations) (download)
Sun Mar 13 01:44:02 2016 UTC (8 years, 1 month ago) by jmc
Branch: MAIN
CVS Tags: checkpoint66g, checkpoint66f, checkpoint66e, checkpoint66d, checkpoint66c, checkpoint66b, checkpoint66a, checkpoint66o, checkpoint66n, checkpoint66m, checkpoint66l, checkpoint66k, checkpoint66j, checkpoint66i, checkpoint66h, checkpoint65z, checkpoint65x, checkpoint65y, checkpoint65v, checkpoint65w, checkpoint65u, HEAD 
- from Darren: add PPM and PQM advection schemes (number 40-42 and 50-52)
  with 2 types of limiter (see: Engwirda & Kelley, submit. to JCP);
  Note (from Darren): unlimited PPM/PQM scheme (40 & 50) are just for
  testing and not for actual use.
1 C $Header: $
2 C $Name: $
3
4 # include "GAD_OPTIONS.h"
5
6 C-- File gad_plm_fun.F: Routines for monotone piecewise linear method.
7 C-- Contents
8 C-- o GAD_PLM_FUN_U
9 C-- o GAD_PLM_FUN_V
10
11 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
12
13 SUBROUTINE GAD_PLM_FUN_U(
14 I ffll,ff00,ffrr,
15 O dfds)
16 C |================================================================|
17 C | PLM_FUN_U: monotone piecewise linear method. |
18 C | - uniform grid-spacing variant. |
19 C |================================================================|
20
21 implicit none
22
23 C ====================================================== arguments
24 _RL ffll,ff00,ffrr
25 _RL dfds(-1:+1)
26
27 C ====================================================== variables
28 _RL fell,ferr,scal
29 _RL epsil
30 PARAMETER( epsil = 1. _d -16 )
31
32 dfds(-1) = ff00 - ffll
33 dfds(+1) = ffrr - ff00
34
35 if (dfds(-1) * dfds(+1) .gt. 0.0 _d 0) then
36
37 C ======================================= calc. ll//rr edge values
38 fell = 0.5 _d 0 * (ffll + ff00)
39 ferr = 0.5 _d 0 * (ff00 + ffrr)
40
41 C ======================================= calc. centred derivative
42 dfds(+0) =
43 & 0.5 _d 0 * (ferr - fell)
44
45 C ======================================= monotonic slope-limiting
46 scal = min(abs(dfds(-1)),
47 & abs(dfds(+1)))
48 & / max(abs(dfds(+0)), epsil)
49 c & / max(abs(dfds(+0)), epsilon(ff00))
50 scal = min(scal, 1.0 _d 0)
51
52 dfds(+0) = scal * dfds(+0)
53
54 else
55
56 C ======================================= flatten if local extrema
57 dfds(+0) = 0.0 _d 0
58
59 end if
60
61 dfds(-1) = 0.5 _d 0 * dfds(-1)
62 dfds(+1) = 0.5 _d 0 * dfds(+1)
63
64 return
65
66 c end subroutine GAD_PLM_FUN_U
67 end
68
69 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
70
71 SUBROUTINE GAD_PLM_FUN_V(
72 I ffll,ff00,ffrr,
73 I ddll,dd00,ddrr,
74 O dfds)
75 C |================================================================|
76 C | PLM_FUN_V: monotone piecewise linear method. |
77 C | - variable grid-spacing variant. |
78 C |================================================================|
79
80 implicit none
81
82 C ====================================================== arguments
83 _RL ffll,ff00,ffrr
84 _RL ddll,dd00,ddrr
85 _RL dfds(-1:+1)
86
87 C ====================================================== variables
88 _RL fell,ferr,scal
89 _RL epsil
90 PARAMETER( epsil = 1. _d -16 )
91
92 dfds(-1) = ff00 - ffll
93 dfds(+1) = ffrr - ff00
94
95 if (dfds(-1) * dfds(+1) .gt. 0.0 _d 0) then
96
97 C ======================================= calc. ll//rr edge values
98 fell = (dd00 * ffll + ddll * ff00)
99 & / (ddll + dd00)
100 ferr = (ddrr * ff00 + dd00 * ffrr)
101 & / (dd00 + ddrr)
102
103 C ======================================= calc. centred derivative
104 dfds(+0) =
105 & 0.5 _d 0 * (ferr - fell)
106
107 C ======================================= monotonic slope-limiting
108 scal = min(abs(dfds(-1)),
109 & abs(dfds(+1)))
110 & / max(abs(dfds(+0)), epsil)
111 c & / max(abs(dfds(+0)), epsilon(ff00))
112 scal = min(scal, 1.0 _d 0)
113
114 dfds(+0) = scal * dfds(+0)
115
116 else
117
118 C ======================================= flatten if local extrema
119 dfds(+0) = 0.0 _d 0
120
121 end if
122
123 C == !! check this
124 dfds(-1) = dfds(-1) / (ddll + dd00) * dd00
125 dfds(+1) = dfds(+1) / (dd00 + ddrr) * dd00
126
127 return
128
129 c end subroutine GAD_PLM_FUN_V
130 end
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