Onno: please can you explain what you don't like about the output? all the best --cjc On 26 June 2016 at 00:35, Onno Bokhove <O.Bokhove@leeds.ac.uk> wrote:

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> 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.imperial.ac.uk/people/colin.cotter www.cambridge.org/9781107663916