Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

flow and transport model

Please login with a confirmed email address before reporting spam

Hi everyone,

I have a 2D grid (100x50) which each of its grid has a permeability value (such a a 2D map of permeability distribution for a porous medium). I want to put a contaminant a specific point and under some hypothetical conditions (such flow rate, porosity, ....) see its distribution in different times (such as 2 days, 1 month, 3 months,...)
Can anyone help me about it? my main problem is that how I should define a 2D permeability grid in COMSOL!
I attached a file in which I clear my mean.


Thanks a lot,
Pejman


5 Replies Last Post 25.05.2011, 16:23 GMT-4

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 23.05.2011, 19:47 GMT-4
To define 2D or 3D properties such as hydraulic conductivity on a domain Comsol gives you a variety of methods. For more details you should search about variables and expressions section in comsol help file.
The way I'm doing this, myself is through matlab. I first create in Matlab a struct variable such as K with three fields.
K.x=[coordinates in x direction]
K.y=[coordinates in y direction]
K.data=[values of your property] Note that this is not a 2D matrix but a 1D with length equal to length(K.x)*length(K.y).
Unfortunately i don't remember right now whether you should write the x values first or the y values, you could try both and see which one gives you the correct result.
Once you create the variable you can import it (at least in 3.5 I don't know about 4) by creating a new function then choose interpolation and use data from Matlab.

Then you can use the function you have defined. Let's say the function name is PERM, then you should give as value in the field of the property: PERM(x,y) if the property is 2d or PERM(x,y,z) in 3D case. Don't forget to make sure that the output of PERM function is always in [m/sec].

Good luck

Giorgos
To define 2D or 3D properties such as hydraulic conductivity on a domain Comsol gives you a variety of methods. For more details you should search about variables and expressions section in comsol help file. The way I'm doing this, myself is through matlab. I first create in Matlab a struct variable such as K with three fields. K.x=[coordinates in x direction] K.y=[coordinates in y direction] K.data=[values of your property] Note that this is not a 2D matrix but a 1D with length equal to length(K.x)*length(K.y). Unfortunately i don't remember right now whether you should write the x values first or the y values, you could try both and see which one gives you the correct result. Once you create the variable you can import it (at least in 3.5 I don't know about 4) by creating a new function then choose interpolation and use data from Matlab. Then you can use the function you have defined. Let's say the function name is PERM, then you should give as value in the field of the property: PERM(x,y) if the property is 2d or PERM(x,y,z) in 3D case. Don't forget to make sure that the output of PERM function is always in [m/sec]. Good luck Giorgos

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 24.05.2011, 13:00 GMT-4
Dear Giorgos,

Thanks a lot for all of your effort to answer to my question.
Actually I am very very new in COMSOL! and when I see that most of the users like and prefer to work with the 3.5 version I installed it today.
Please take a look on my data in attachment and see that is is possible I model the contaminant transportation via COMSOL in different times or not! you can see the data easily in MATLAB by imagesc(). The data are hydraulic conductivity.

Thanks again,
Pejman
Dear Giorgos, Thanks a lot for all of your effort to answer to my question. Actually I am very very new in COMSOL! and when I see that most of the users like and prefer to work with the 3.5 version I installed it today. Please take a look on my data in attachment and see that is is possible I model the contaminant transportation via COMSOL in different times or not! you can see the data easily in MATLAB by imagesc(). The data are hydraulic conductivity. Thanks again, Pejman


Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 24.05.2011, 13:00 GMT-4
Dear Giorgos,

Thanks a lot for all of your effort to answer to my question.
Actually I am very very new in COMSOL! and when I see that most of the users like and prefer to work with the 3.5 version I installed it today.
Please take a look on my data in attachment and see that is is possible I model the contaminant transportation via COMSOL in different times or not! you can see the data easily in MATLAB by imagesc(). The data are hydraulic conductivity.

Thanks again,
Pejman
Dear Giorgos, Thanks a lot for all of your effort to answer to my question. Actually I am very very new in COMSOL! and when I see that most of the users like and prefer to work with the 3.5 version I installed it today. Please take a look on my data in attachment and see that is is possible I model the contaminant transportation via COMSOL in different times or not! you can see the data easily in MATLAB by imagesc(). The data are hydraulic conductivity. Thanks again, Pejman

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 25.05.2011, 15:23 GMT-4
Definitely Comsol can solve transient state transport models of many kinds.

I don't know if your problem has any peculiarities that Comsol cannot handle, however before solving your own problems I fully recommend you to go through the transport examples given by Comsol. They are very helpful to understand the Comsol way of thinking.

Giorgos.

PS. As for the data you attached, are you sure they represent hydraulic conductivity? there are many negative values.
Definitely Comsol can solve transient state transport models of many kinds. I don't know if your problem has any peculiarities that Comsol cannot handle, however before solving your own problems I fully recommend you to go through the transport examples given by Comsol. They are very helpful to understand the Comsol way of thinking. Giorgos. PS. As for the data you attached, are you sure they represent hydraulic conductivity? there are many negative values.

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 25.05.2011, 16:23 GMT-4
Up to this time I am sure that COMSOL can handles my problem. My main problem is that COMSOL consider the hydraulic connectivity (HC) constant for all of the grid while I want that each grid have a specific value. Therefore, in other words I do not know that how I should enter the different values for HC!
Also the data are HC and I just scaled them into [-5 5]. Here is the original data.

Thanks for your help.
Up to this time I am sure that COMSOL can handles my problem. My main problem is that COMSOL consider the hydraulic connectivity (HC) constant for all of the grid while I want that each grid have a specific value. Therefore, in other words I do not know that how I should enter the different values for HC! Also the data are HC and I just scaled them into [-5 5]. Here is the original data. Thanks for your help.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.