Are you performing the interpolation every time step? On 30 September 2015 at 15:36, Anna Kalogirou <a.kalogirou@leeds.ac.uk> wrote:
The solution behaves as expected when I define Q as a function, but in the other case there seems to be some kind of instability and I get a very strange result.
Anna.
On 30/09/15 15:28, Lawrence Mitchell wrote:
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On 30/09/15 15:19, Anna Kalogirou wrote:
Dear all,
I have a very simple, yet not so obvious - to me at least - question:
If I define an expression which does not depend on space variables, for example
Q_expr = Expression("A*sin(2*pi*F*t)", t=t, A=A, F=F) Q.interpolate(Q_expr)
shouldn't this be equivalent to just writing Q as a scalar,
Q = A*sin(2*pi*F*t) ?
This quantity Q is then used in a weak form to multiply the test function v on a boundary, e.g. Q*v*ds_v(1).
I get different results for the two cases. Clearly, in the 1st case Q is a function while in the 2nd case it is a scalar, but I don't see why this would give different results. I might be missing something obvious here... These ought to be equivalent. But can you describe how they are different?
Lawrence.
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Dr Anna Kalogirou Research Fellow School of Mathematics University of Leeds
http://www1.maths.leeds.ac.uk/~matak/
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Yes I update the time component of the expession at every time step. On 30/09/15 15:38, Andrew McRae wrote:
Are you performing the interpolation every time step?
On 30 September 2015 at 15:36, Anna Kalogirou <a.kalogirou@leeds.ac.uk <mailto:a.kalogirou@leeds.ac.uk>> wrote:
The solution behaves as expected when I define Q as a function, but in the other case there seems to be some kind of instability and I get a very strange result.
Anna.
On 30/09/15 15:28, Lawrence Mitchell wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 30/09/15 15:19, Anna Kalogirou wrote: >> Dear all, >> >> I have a very simple, yet not so obvious - to me at least - >> question: >> >> If I define an expression which does not depend on space variables, >> for example >> >> Q_expr = Expression("A*sin(2*pi*F*t)", t=t, A=A, F=F) >> Q.interpolate(Q_expr) >> >> shouldn't this be equivalent to just writing Q as a scalar, >> >> Q = A*sin(2*pi*F*t) ? >> >> This quantity Q is then used in a weak form to multiply the test >> function v on a boundary, e.g. Q*v*ds_v(1). >> >> I get different results for the two cases. Clearly, in the 1st case >> Q is a function while in the 2nd case it is a scalar, but I don't >> see why this would give different results. I might be missing >> something obvious here... > These ought to be equivalent. But can you describe how they are > different? > > > Lawrence. > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > > iQEcBAEBAgAGBQJWC/GPAAoJECOc1kQ8PEYvGncIAM7WI2JkrZ5Y1wZMyJAHNDJG > Ca476ZQcNCzKsZ/ntPL9SoXsbXu4Uu2mIVuT4r30VBc/NAEuBdkKppVmiwS3DTsP > qzLVP2nRL1ENxYWOUk8pWryE/jffyPP9ny5gHoRLPP/09vL3e4y8jKplw0bmKMgZ > UVvcp+kL1hqFujvCddxpym8gg4Y3UrMTdD2MaYJ8WHaFeqB9ZPNWomv24ZKKWhHU > HAms5sgsNedvdrgIY32AH2AARRysk4AsLsfjYymsiXPrOyPrlG5V2Muf4gKdqID1 > MRWiL7p6ZVxLnOytF4NtFRUItYLKcOrv487IIIHVfl+TVvmKO+IJpXDyx5wyZcY= > =EkO8 > -----END PGP SIGNATURE----- > > _______________________________________________ > firedrake mailing list > firedrake@imperial.ac.uk <mailto:firedrake@imperial.ac.uk> > https://mailman.ic.ac.uk/mailman/listinfo/firedrake
--
Dr Anna Kalogirou Research Fellow School of Mathematics University of Leeds
http://www1.maths.leeds.ac.uk/~matak/ <http://www1.maths.leeds.ac.uk/%7Ematak/>
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-- Dr Anna Kalogirou Research Fellow School of Mathematics University of Leeds http://www1.maths.leeds.ac.uk/~matak/
participants (2)
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Andrew McRae
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Anna Kalogirou