Re: NDSolve error for partial DV

• To: mathgroup at smc.vnet.net
• Subject: [mg107749] Re: NDSolve error for partial DV
• From: dh <dh at metrohm.com>
• Date: Thu, 25 Feb 2010 01:54:18 -0500 (EST)
• References: <hm321l\$m82\$1@smc.vnet.net>

```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.
>
>
> M.
>

--

Daniel Huber
Metrohm Ltd.
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CH-9100 Herisau
Tel. +41 71 353 8585, Fax +41 71 353 8907
E-Mail:<mailto:dh at metrohm.com>
Internet:<http://www.metrohm.com>

```

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