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Access depenant variable in Matlab code
Posted Jul 23, 2013, 5:07 p.m. EDT Interfacing, Computational Fluid Dynamics (CFD), Chemical Reaction Engineering Version 3.5a 1 Reply
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Hi
I am trying to develop a diffusion-reaction model using COMSOL - MATLAB interface. My model requires access to dependent variables during the execution so that they can be passed to an external function to calculate the flux at each point.
Can you please help me how to access dependent variables?
I am trying to develop a diffusion-reaction model using COMSOL - MATLAB interface. My model requires access to dependent variables during the execution so that they can be passed to an external function to calculate the flux at each point.
Can you please help me how to access dependent variables?
1 Reply Last Post Jul 24, 2013, 5:42 a.m. EDT
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Posted:
1 decade ago
Hi,
In 4.3a, this is possible in many ways. (I think in 4.3b, these commands may have been revised).
1. You can output the solution vector for the entire problem using "mphgetU" command (see API reference manual). The only caution is that you must study the output format especially when you have more than one degree of freedom per node or when you have multiple domains with different element type or discretization orders.
2. Alternatively, the simplest is to use "mpheval" command to extract either nodal or gaussian point values of dependent variables. Again see recent manual for syntax.
I am not familiar with corresponding commands for version 3.5a. But if I faintly remember,
1. To get solution vector similar to (1) above, you may need to use the fem structure with the syntax being somewhat like:
dependent_variable = fem.sol.u()
2. And similar to (2) above, you may need to use postinterp I think. It will be somewhat like:
dependent_variable = postinterp(fem,'u',coords(),'Solnum','end')';
As I said you need to get the exact syntax from ver 3.5a manuals. May be there are other more appropriate commands for your purpose.
Suresh
In 4.3a, this is possible in many ways. (I think in 4.3b, these commands may have been revised).
1. You can output the solution vector for the entire problem using "mphgetU" command (see API reference manual). The only caution is that you must study the output format especially when you have more than one degree of freedom per node or when you have multiple domains with different element type or discretization orders.
2. Alternatively, the simplest is to use "mpheval" command to extract either nodal or gaussian point values of dependent variables. Again see recent manual for syntax.
I am not familiar with corresponding commands for version 3.5a. But if I faintly remember,
1. To get solution vector similar to (1) above, you may need to use the fem structure with the syntax being somewhat like:
dependent_variable = fem.sol.u()
2. And similar to (2) above, you may need to use postinterp I think. It will be somewhat like:
dependent_variable = postinterp(fem,'u',coords(),'Solnum','end')';
As I said you need to get the exact syntax from ver 3.5a manuals. May be there are other more appropriate commands for your purpose.
Suresh