iMechanica - Comments for "Problem in implementation of free volume diffusion equation"
https://imechanica.org/node/10077
Comments for "Problem in implementation of free volume diffusion equation"enHi,
I think solving a
https://imechanica.org/comment/16567#comment-16567
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<p><em>In reply to <a href="https://imechanica.org/node/10077">Problem in implementation of free volume diffusion equation</a></em></p>
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Hi,
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I think solving a diffusion equation in VUMAT is completely wrong way. If you deal with a coupled problem (stress-displacement + something else, like diffusion or heat transfer) specific elements are used with additional degrees of freedom (unknowns in the nodes). In this case when UMAT is called V is already known and you have to do only stress update as it is described in the manual. VUMAT deals with material characteristics in one point. This is sufficient to program non-gradient (also known as first-order) models. Access to variables in the neighborhood is possible through utility routines (see manual), but anyway it is very unlikely that you have to solve diffusion equation in VUMAT.
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</ul>Fri, 15 Apr 2011 04:54:29 +0000Alexander Polishchukcomment 16567 at https://imechanica.org
Not sure if I have got
https://imechanica.org/comment/16557#comment-16557
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<p><em>In reply to <a href="https://imechanica.org/node/10077">Problem in implementation of free volume diffusion equation</a></em></p>
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Not sure if I have got your question. If you use the forward Euler scheme to discrtise the system equation, you only need to calculate Laplacian(V) at last time point at which the whole V field is supposed to be know.
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</ul>Wed, 13 Apr 2011 10:12:10 +0000zhang_xiaodongcomment 16557 at https://imechanica.org