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Initial values - how to input vector rather than constant?

Posted 7 févr. 2014, 19:47 UTC−5 Parameters, Variables, & Functions Version 4.3a, Version 4.3b, Version 4.4 3 Replies

dnh37
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I'm using 1D General Form PDE to solve some coupled PDEs.

I have set up the PDEs and boundary conditions. Now I have to set up initial conditions.

Say I have 5 mesh points. Then for a particular parameter I want the inital conditions [0,2,4,6,8] or something, so the left-most mesh point is zero and the right-most mesh point initial condition is 8.

However when I click on Model 1 > General Form PDE > Initial values node, I see a place to enter the initial conditions, however this appears to only accept a constant. So if I enter "3" then I get [3,3,3,3,3]. I have tried the following:

range(0,8/(5-1),8) --- it accepts this input but gives an error at runtime about not recognizing "range"

or I simply tried

[0,2,4,6,8] --- however it does not accept this input.

How to give a non-constant input initial condition?

Thanks!
3 Replies Last Post 15 avr. 2014, 05:32 UTC−4
Suresh Seetharam
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Posted: 1 decade ago 8 févr. 2014, 16:35 UTC−5
Hi,


Did you try to define initial condition parameter as a function of space. Essentially, in the initial values field, you type:

init(x) in 1D or init(x,y) in 2D or init(x,y,z) in 3D.

But you have to define "init" under interpolation function.


Suresh
Hi, Did you try to define initial condition parameter as a function of space. Essentially, in the initial values field, you type: init(x) in 1D or init(x,y) in 2D or init(x,y,z) in 3D. But you have to define "init" under interpolation function. Suresh
dnh37
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Posted: 1 decade ago 9 févr. 2014, 12:17 UTC−5
That did it! Thanks!
That did it! Thanks!
Lukas Alberts
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Posted: 1 decade ago 15 avr. 2014, 05:32 UTC−4
Hello,

that does not work for me? I am in axisym 2D case? is it then different?

the init(r,z) or init(x,y) in the function definitions is well plotted,

but under the initial value it does not appear?

thanks

lukas

my mistake was in the units.. init(1000*r,1000*z) was right
Hello, that does not work for me? I am in axisym 2D case? is it then different? the init(r,z) or init(x,y) in the function definitions is well plotted, but under the initial value it does not appear? thanks lukas my mistake was in the units.. init(1000*r,1000*z) was right

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