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Time to Reach Steady State in a Diffusion Problem
Posted Feb 23, 2013, 1:55 p.m. EST 4 Replies
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Hello,
Is someone able to help me, please?
I'm using COMSOL to model a diffusion problem. I have solved it using the stationary solver. I am able to see that at steady state the concentration on the far edge is 0.025 mols, by clicking on the image and viewing the results tab.
Is there a better (more automated) way to get this value?
I would also like to know the time to reach steady state - the definition of steady state I have chosen is 95% of the concentration when solved using the stationary solver. How would I find that? So far I have used the time dependent solver, and laboriously clicked through each time point, judging when the concentration reaches 95% using the results tab.
I'm certain there must be a better way of doing this, but I'm unable to find the answer in the forum. Hope someone can help, thanks in advance.
Is someone able to help me, please?
I'm using COMSOL to model a diffusion problem. I have solved it using the stationary solver. I am able to see that at steady state the concentration on the far edge is 0.025 mols, by clicking on the image and viewing the results tab.
Is there a better (more automated) way to get this value?
I would also like to know the time to reach steady state - the definition of steady state I have chosen is 95% of the concentration when solved using the stationary solver. How would I find that? So far I have used the time dependent solver, and laboriously clicked through each time point, judging when the concentration reaches 95% using the results tab.
I'm certain there must be a better way of doing this, but I'm unable to find the answer in the forum. Hope someone can help, thanks in advance.
4 Replies Last Post Mar 4, 2013, 12:35 p.m. EST
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Posted:
1 decade ago
Hi
you should study the "Results - Derived Values section, here you can Postprocess the Data Set results and then plot easily the results.
You have postprocessing operators such as integration averages, min, max and more
--
Good luck
Ivar
you should study the "Results - Derived Values section, here you can Postprocess the Data Set results and then plot easily the results.
You have postprocessing operators such as integration averages, min, max and more
--
Good luck
Ivar
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Posted:
1 decade ago
Thanks for your help.
I'm now able to evaluate and record the concentration at a point.
Is there a quick way of evaluating a range of times?
Is there a way to extract the time to steady state?
Thanks
I'm now able to evaluate and record the concentration at a point.
Is there a quick way of evaluating a range of times?
Is there a way to extract the time to steady state?
Thanks
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Posted:
1 decade ago
Hi
if you use the time solver you can either use the Derived values to extract complex or integration values versus the time, or you can integrate over the time (see help operators, postprocessing only) and get global values
Time o steady state depends on your diffusion, so you need to add some equations, or add a stationary solver to fins the INF value and check when you get to exp(-1) amplitude
--
Good luck
Ivar
if you use the time solver you can either use the Derived values to extract complex or integration values versus the time, or you can integrate over the time (see help operators, postprocessing only) and get global values
Time o steady state depends on your diffusion, so you need to add some equations, or add a stationary solver to fins the INF value and check when you get to exp(-1) amplitude
--
Good luck
Ivar
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Posted:
1 decade ago
That's great.
Thank you for your help :)
Kat
Thank you for your help :)
Kat