On Wed, Feb 20, 2013 at 1:54 PM, Pierre de Buyl <[email protected]> wrote:
> Hi Daniel, > > Thanks for your reply :-) > > I started analyzing the data, as I need to use the result as a step in > another > computation. > > What I want is n(theta, r) where r is fixed. I can obtain this value by > calling > the variable "n" with a list of coordinates. I do this by adding the > following > code: > > def radial_value(th,r,order=1): > x = r*np.sin(th) > y = r*np.cos(th) > return n((x, y), order=order) > > and I plot > plot(theta, radial_value(theta, 1.5)) > here, 1.5 is arbitrary. I need the value at different radii depending on > other > parameters. > > Around theta=0 and theta=pi, which are close to the left of my domain > (cylindrical radius=0), I expect zero flux (-> flat function). However, the > slope is non-negligible. I attach a plot of n(theta,r=1.5), for sigma=9 and > v=-0.01). > > The result doesn't change much if I shift the mesh with > + ((1e-5,),(0.,)) > > Does it get any better as you increase the perturbation? > Could it be the the multiplication of the cell volume and face area by the > radius cause of bad handling of the zero flux BC on the left of the domain > with > radius=0. > Yes. I have experienced this issue before. Play with the shift and see if things approve. I'm curious as to why you aren't using the CylindricalGrid2D class? Try using that at least to test against. > > In that case, I couldn't solve satisfactorily my axisymmetric problem, is > this > right? > I'm sure it is possible, but I haven't tried to reproduce your work yet and really figure out what is happening. Try the CylindricalGrid2D just to make sure that the various changes for the axisymmetric problem are being handled correctly in your code and then we can go from there. Also see if things improve as the shift is increased away from zero and that the solutions are adequately converged. That's the easy diagnostics. Confirm those first. -- Daniel Wheeler
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