Changes between Version 7 and Version 8 of 2017WP/ENHANCE-05_Gurvan-RK3

Timestamp:

2017-07-24T16:25:06+02:00 (7 years ago)

Author:

gm

Comment:

--

2017WP/ENHANCE-05_Gurvan-RK3

@@ -5 +5 @@
 || '''Action''' || ENHANCE-5_Gurvan — RK-3 time stepping ||
 || '''PI(S)''' || Gurvan Madec ||
-{{{#!td
-'''Digest'''
-}}}
-{{{#!td
- Introduce an optional RK3 time-stepping scheme. The scheme will:
+
+{{{#!td '''Digest''' }}} {{{#!td
+
+  Introduce an optional RK3 time-stepping scheme. The scheme will:
 
  1. be a valuable alternative to the current Modified Leap-Frog (MLF, Leclair and Madec OM2009) scheme,
@@ -15 +14 @@
  1. allow [http://agrif.imag.fr/ AGRIF] to be exactly conservative, and
  1. make much more easier to use time coarsening of TRC and OFF-line variable volume calculation
+ 1. make feasible to properly implement an implicit computation of top and bottom friction (properly means consistent with the ssh time splitting scheme)
+
+
+
+As such a change will impact many module of OPA, it has been preferred to develop the RK3 version in a separate directory, RK3_SRC, put at the same level as OPA_SRC and being a copy of OPA_SRC as starting point. 
+
+In addition to the RK3 scheme, a Forward-Bacward Scheme (FBS) will be introduced. The goals associated with FBS are the following:
+
+   ''(i)'' FB scheme is also a two levels time-stepping scheme but much simpler than a RK3. Its implementation will prepare all the required environment for the RK3 scheme, while been much easier to develop and test.
+
+   ''(ii)'' FB scheme may be a valuable alternative for low resolution simulations (in particular ORCA 2° and 1°) which do not necessarily need a high order time-stepping scheme, although FB scheme requires to used UBS scheme on advection of both dynamics and tracers.
 
 In practice the work is to :
 
- * add all time varying fields as argument of all DYN and TRA routines (as RK3 schemes uses the same tendency terms as the Leap-Frog scheme, but it calls them several times by time step)
- * introduce a stpRK3.F90  time-stepping module (which will contain a stp_RK3 routine)
- * move the existing Modified Leap-Frog  time stepping (step.F90) in stpMLF.F90 module (containing stp routine renamed stp_MLF)
- * change the CALL to stp routine in memogcm.F90 by a CALL to either stp_MLF or stp_RK3 depending of namelist parameters
-}}}
-|-
+ * start from the trunk, updated with HPC09 branch (i.e. ZDF modifications)
+
+
+ * create RK3_SRC directory a a copy of OPA_SRC
+
+
+ * implement the FB scheme in a stp_fbs routine (found either in step.F90 or in stpfbs.F90), implying changes in most of SBC, TRA, DYN and ZDF modules
+
+
+ * implement the RK3 scheme in a stp_rk3 routine (found either in step.F90 or stprk3.F90)
+
+
+
+}}} |-
+
 || '''Dependencies''' || no ||
 || '''Target''' || 2017 merge party ||
-|| '''Trac Ticket''' || [ticket:1911 #1911] ||
+|| '''Trac Ticket''' || #1911 ||
 || '''SVN branch''' || [browser:branches/2017/dev_r7881_ENHANCE09_RK3 dev_r7881_ENHANCE09_RK3] ||
 || '''Previewer(s)''' || ''Names'' ||
@@ -32 +51 @@
 || '''Status''' || To be developed ||
 || '''Link''' || [[ExtractUrl(.)]] ||
-
 ==  ==
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