[MITgcm-devel] advcfl_W_hf_max

[Alistair Adcroft]

D.,

Yes - it does hold because the W being used in the calculation of the CFL
number is infact W*. The upper limit of 0.25 is for the explicit ABII linear
advection schemes. Further, using the linear schemes, the CFL limits are
additive. In contrast, the flux-limited methods are stable all the way upto
CFL=1 and independent (CFL(u)=.9 and CFL(v)=.9 is stable). In principle, the
third order flux-limited scheme "33" is stable upto CFL=2 and most accurate
(fourth order) in the vicinity of CFL=1.

BTW, when the model blows up - plot the recent history of the CFL numbers...

A.
--
Dr Alistair Adcroft            http://www.mit.edu/~adcroft
MIT Climate Modeling Initiative        tel: (617) 253-5938
EAPS 54-1523,  77 Massachusetts Ave,  Cambridge,  MA,  USA

-----Original Message-----
From: mitgcm-devel-bounces at mitgcm.org
[mailto:mitgcm-devel-bounces at mitgcm.org] On Behalf Of Dimitris Menemenlis
Sent: Tuesday, January 06, 2004 12:46 PM
To: mitgcm
Subject: [MITgcm-devel] advcfl_W_hf_max


>> "advcfl_W_hf_max" is the vertical CFL number including the variable
>> grid resolution and most likely to be above 0.2

Alistair, does this also hold when using z*?

For the 510*510 cube, advcfl_W_hf_max is generally higher
than 0.2.  Typically ranges from 0.3 to 0.7, with occasional excursions all
the way up to 1 or 2.

D.

-- 
Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Jet Propulsion Lab, California Insitute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
tel: 818-354-1656;  fax: 818-393-6720

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