Re: [firedrake] upwind example remark; extension to CN in time
Hi Onno, Did you see that you set theta to 0.0? If you want CN then it should be 0.5? cheers --cjc On 25 June 2016 at 16:05, Onno Bokhove <O.Bokhove@leeds.ac.uk> wrote:
Hi FDs,
(i) The upwind example is odd in that the real boundaries are treated
in a special way rather than setting the outside value in
the same numerical flux as anywhere else;
my question is how this can be fixed?
So no special terms at the in- and outflow, just specify
the outside velocity used. This is imo the proper DG way not was is done
now.
(ii) Attached my attempt to do a time dependent advection
with Crank Nicolson, which works but does not yet
give the right answer, in part due to (i).
[I don't understand why I have to make
my theta variable that a constant but other wise it did not work.]
Any suggestions, corrections, also on other silly things done by me?
Next step is to extend to system with 3 equations; hence the few extra but unused variables.
Thanks, from midnight Seoul in old style Korean guesthouse.
Onno ------------------------------
-- http://www.imperial.ac.uk/people/colin.cotter www.cambridge.org/9781107663916
Colin: I know as I was comparing different theta's! Francis: Oh I see that it does not allow to attach the mesh file to the email. Odd. I attach the base file instead. I know it is a rectangle I assure you it will be changed to a 4-snaked channel. ________________________________ From: firedrake-bounces@imperial.ac.uk <firedrake-bounces@imperial.ac.uk> on behalf of Colin Cotter <colin.cotter@imperial.ac.uk> Sent: Saturday, June 25, 2016 9:25 PM To: firedrake Subject: Re: [firedrake] upwind example remark; extension to CN in time Hi Onno, Did you see that you set theta to 0.0? If you want CN then it should be 0.5? cheers --cjc On 25 June 2016 at 16:05, Onno Bokhove <O.Bokhove@leeds.ac.uk<mailto:O.Bokhove@leeds.ac.uk>> wrote: Hi FDs, (i) The upwind example is odd in that the real boundaries are treated in a special way rather than setting the outside value in the same numerical flux as anywhere else; my question is how this can be fixed? So no special terms at the in- and outflow, just specify the outside velocity used. This is imo the proper DG way not was is done now. (ii) Attached my attempt to do a time dependent advection with Crank Nicolson, which works but does not yet give the right answer, in part due to (i). [I don't understand why I have to make my theta variable that a constant but other wise it did not work.] Any suggestions, corrections, also on other silly things done by me? Next step is to extend to system with 3 equations; hence the few extra but unused variables. Thanks, from midnight Seoul in old style Korean guesthouse. Onno ________________________________ -- http://www.imperial.ac.uk/people/colin.cotter www.cambridge.org/9781107663916<http://www.cambridge.org/9781107663916> [http://assets.cambridge.org/97811076/63916/cover/9781107663916.jpg]
participants (2)
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Colin Cotter
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Onno Bokhove