NDSolve error for partial DV
in [Mathematica]
|
Prev: Must tell Compile that Clip returns a number.
Next: WCSTools - Display astronomical FITS files with coordinate grid
From: Menl on 24 Feb 2010 06:20 I try to numerically solve a set of 2 DV containing two functions depending on two variables x and t. x represents the position and t represents time. I have defined several boundary conditions ( for x) and one initial condition ( for t) However I receive an error from Mathematica so there is obviously some error. The error is : NDSolve::ivone: "Boundary values may only be specified for one independent variable. Initial values may only be specified at one value of the other independent variable." The code is as follows: sw7t = NDSolve[{Bs (D[g[x, t], {x, 2}] - D[w[x, t], {x, 3}]) - A g[x, t] == 0 //. vars, A D[g[x, t], {x, 1}] - (Bbot + Btop) D[w[x, t], {x, 4}] - \[Mu] D[ w[x, t], {t, 2}] == 0 //. vars, w[0, t] == 0, w[3, t] == 0, D [w[x, t], {x, 2}] == 0 //. x -> 0, D [w[x, t], {x, 2}] == 0 //. x -> 3, D [w[x, t], {t, 1}] == 0 //. {t -> 0}, D [g[x, t], {x, 1}] == 0 //. x -> 0, D [g[x, t], {x, 1}] == 0 //. x -> 3}, {w , g}, {x, 0, 3}, {t, 0, 10}] Here the constants used are contained in vars and assigned code. If someone knows where the mistake I would very much like to know. Thanx in advance M.
From: dh on 25 Feb 2010 01:54
Hi, I think you forgot an initial condition for g. Daniel On 24.02.2010 12:20, Menl wrote: > I try to numerically solve a set of 2 DV containing two functions depending on two variables x and t. x represents the position and t represents time. > > I have defined several boundary conditions ( for x) and one initial condition ( for t) > > However I receive an error from Mathematica so there is obviously some error. > > The error is : NDSolve::ivone: "Boundary values may only be specified for one independent variable. Initial values may only be specified at one value of the other independent variable." > > The code is as follows: > > sw7t = NDSolve[{Bs (D[g[x, t], {x, 2}] - D[w[x, t], {x, 3}]) - > A g[x, t] == 0 //. vars, > A D[g[x, t], {x, 1}] - (Bbot + Btop) D[w[x, t], {x, 4}] - \[Mu] D[ > w[x, t], {t, 2}] == 0 //. vars, w[0, t] == 0, w[3, t] == 0, > D [w[x, t], {x, 2}] == 0 //. x -> 0, > D [w[x, t], {x, 2}] == 0 //. x -> 3, > D [w[x, t], {t, 1}] == 0 //. {t -> 0}, > D [g[x, t], {x, 1}] == 0 //. x -> 0, > D [g[x, t], {x, 1}] == 0 //. x -> 3}, {w , g}, {x, 0, 3}, {t, 0, > 10}] > > > Here the constants used are contained in vars and assigned code. > > If someone knows where the mistake I would very much like to know. > > Thanx in advance > > M. > -- Daniel Huber Metrohm Ltd. Oberdorfstr. 68 CH-9100 Herisau Tel. +41 71 353 8585, Fax +41 71 353 8907 E-Mail:<mailto:dh(a)metrohm.com> Internet:<http://www.metrohm.com> |