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modeling of turbulent flow in pipe and annulus. (pipe has porous wall)
Posted 10.12.2013, 21:34 GMT-5 Computational Fluid Dynamics (CFD) Version 4.2, Version 4.3b 7 Replies
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Hi, I am trying to model turbulent flow in a pipe and annulus and find the pressure and velocity distributions. The flow is going to the pipe and is coming back from the annulus. The pipe has porous wall so that the flow in the pipe can permeate to the annulus and come back. I attach a doc file containing a figure showing the configuration.
to model it in Comsol, I added 3 different physics.
1- “Turbulent flow (k-ε)” for the flow through the pipe
2- “Darcy’s law” for flow through the porous wall.
3- “Turbulent flow (k-ε)” for the flow through the annulus
Actually, “outlet” boundary condition in each of these physics is “inlet” boundary condition for the other physics. For example, “outlet” of the pipe is “inlet of the porous media”, and vice versa. How can I define this condition in Comsol so that all these 3 physics become coupled? I tried to couple these physics together by using “dependent variable” of one physic as “boundary condition” for the other one. For example, ”, I used normal stress = p2 as “outlet” of the pipe. where p2 is dependent variable in “Darcy’s law” (pressure in porous media).
It seems in the “results” section they are not still coupled. If you go to the “results” section and take a look at line graphs named “ pipe (r direction)”, “ porous media (r direction)”, “ annulus (r direction)”, you can see that the velocity distribution in each domain are not consistent with each other . Do I need to do anything else to couple these 3 physics together?
I really appreciate if someone can help me with that
to model it in Comsol, I added 3 different physics.
1- “Turbulent flow (k-ε)” for the flow through the pipe
2- “Darcy’s law” for flow through the porous wall.
3- “Turbulent flow (k-ε)” for the flow through the annulus
Actually, “outlet” boundary condition in each of these physics is “inlet” boundary condition for the other physics. For example, “outlet” of the pipe is “inlet of the porous media”, and vice versa. How can I define this condition in Comsol so that all these 3 physics become coupled? I tried to couple these physics together by using “dependent variable” of one physic as “boundary condition” for the other one. For example, ”, I used normal stress = p2 as “outlet” of the pipe. where p2 is dependent variable in “Darcy’s law” (pressure in porous media).
It seems in the “results” section they are not still coupled. If you go to the “results” section and take a look at line graphs named “ pipe (r direction)”, “ porous media (r direction)”, “ annulus (r direction)”, you can see that the velocity distribution in each domain are not consistent with each other . Do I need to do anything else to couple these 3 physics together?
I really appreciate if someone can help me with that
7 Replies Last Post 14.03.2014, 15:13 GMT-4
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Posted:
1 decade ago
Hi Fatima,
I see that your dependent variable in the Darcy's Law is p2, if you want to have continuity with your first physics you should call the pressure variable p and not p2 in all the physics.
I'm not able to open the file because you should save it for my versione 4.3a.
--
Marino Miccio
Chemical Engineer
www.youtube.com/ScuolaTech
I see that your dependent variable in the Darcy's Law is p2, if you want to have continuity with your first physics you should call the pressure variable p and not p2 in all the physics.
I'm not able to open the file because you should save it for my versione 4.3a.
--
Marino Miccio
Chemical Engineer
www.youtube.com/ScuolaTech
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Posted:
1 decade ago
Hi, I am trying to model turbulent flow in a pipe and annulus and find the pressure and velocity distributions. The flow is going to the pipe and is coming back from the annulus. The pipe has porous wall so that the flow in the pipe can permeate to the annulus and come back. I attach a doc file containing a figure showing the configuration.
to model it in Comsol, I added 3 different physics.
1- “Turbulent flow (k-ε)” for the flow through the pipe
2- “Darcy’s law” for flow through the porous wall.
3- “Turbulent flow (k-ε)” for the flow through the annulus
Actually, “outlet” boundary condition in each of these physics is “inlet” boundary condition for the other physics. For example, “outlet” of the pipe is “inlet of the porous media”, and vice versa. How can I define this condition in Comsol so that all these 3 physics become coupled? I tried to couple these physics together by using “dependent variable” of one physic as “boundary condition” for the other one. For example, ”, I used normal stress = p2 as “outlet” of the pipe. where p2 is dependent variable in “Darcy’s law” (pressure in porous media).
It seems in the “results” section they are not still coupled. If you go to the “results” section and take a look at line graphs named “ pipe (r direction)”, “ porous media (r direction)”, “ annulus (r direction)”, you can see that the velocity distribution in each domain are not consistent with each other . Do I need to do anything else to couple these 3 physics together?
I really appreciate if someone can help me with that
hi,
how can i define boundary condition at membrane surface? i mean the slip condition, but it depends the permeability.
what do u think?
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Posted:
1 decade ago
Dear Sina,
I attache a file for yoy which shows all the boundary conditions I put in the model,
The porosity of the wall is about 80%. and the permeability is about 0.0018m2.
I did the changes you suggested and put the "outlet of the pipe" and "inlet of the annulus" as " slip wall".
But there is still something wrong in the results. Could you please take a look at the doc file I attached for you and give me your opinion ? Thanks
I attache a file for yoy which shows all the boundary conditions I put in the model,
The porosity of the wall is about 80%. and the permeability is about 0.0018m2.
I did the changes you suggested and put the "outlet of the pipe" and "inlet of the annulus" as " slip wall".
But there is still something wrong in the results. Could you please take a look at the doc file I attached for you and give me your opinion ? Thanks
Attachments:
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Posted:
1 decade ago
Dear Marino,
That would be great if I can model it just with one physic. But unfortunately I don't know how to do it for turbulent flow in pipe with porous wall.
Sorry for having delay.I was trying to run my model in lower version of comsol so that you can open it. I was able to run in in comsol 4.2 now. but the different is that there is no boundary condition " outlet" in the " darcy's law" in comsol 4.2. So, I defined the outlet with " inflow boundary 2" but I used negative sign "-" .
The size of the comsol file is big so I cannot attach it here . So, I got your email from " youtube link" you posted, and emailed it to you. Is this email address yours?
" marino.miccio@tiscali.it"
In the email, I attached the comsol model which is in version 4.2 and hopfully you can open it with comsol 4.3a. and I attach a doc file which defines my problem. I need to have flow in "r" direction. actually, I need to have flow from pipe through porous wall into the annulus. But as you can see from the results the " Vr" which is the r component of velocity in each physics is near zero at different length of the pipe . It means that the flow is going into the end of the pipe (z=10m) which is closed and then passes through the wall and going to the annulus.
I really appreciate your help.
Fatima
That would be great if I can model it just with one physic. But unfortunately I don't know how to do it for turbulent flow in pipe with porous wall.
Sorry for having delay.I was trying to run my model in lower version of comsol so that you can open it. I was able to run in in comsol 4.2 now. but the different is that there is no boundary condition " outlet" in the " darcy's law" in comsol 4.2. So, I defined the outlet with " inflow boundary 2" but I used negative sign "-" .
The size of the comsol file is big so I cannot attach it here . So, I got your email from " youtube link" you posted, and emailed it to you. Is this email address yours?
" marino.miccio@tiscali.it"
In the email, I attached the comsol model which is in version 4.2 and hopfully you can open it with comsol 4.3a. and I attach a doc file which defines my problem. I need to have flow in "r" direction. actually, I need to have flow from pipe through porous wall into the annulus. But as you can see from the results the " Vr" which is the r component of velocity in each physics is near zero at different length of the pipe . It means that the flow is going into the end of the pipe (z=10m) which is closed and then passes through the wall and going to the annulus.
I really appreciate your help.
Fatima
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Posted:
1 decade ago
Hi,
Have you solved this problem yet?
Im building a model which also demands the coupling of darcys law and turbulent model.
Regards
Emil
Have you solved this problem yet?
Im building a model which also demands the coupling of darcys law and turbulent model.
Regards
Emil
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Posted:
1 decade ago
Hi Emil,
Sorry for late response. Not yet but I'm still interested in solving it. maybe we can help each other.
Fatima
Sorry for late response. Not yet but I'm still interested in solving it. maybe we can help each other.
Fatima
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Posted:
1 decade ago
Dear Fatima,
If I understand your question correctly, you are worried that the solution get does not make sense. I have a few suggestions. First, first the inside and the annular pipes, which do not have porous media, you can use the same physics (turbulent flow). For the porous medium use Darcy's law. All your physics were correct, your boundary conditions needed some adjustment. For the interface between the membrane and the two flows, the better boundary condition to use is matching pressures. If you match pressures, mass continuity will match flows and you will get a realistic solution. I have made a few changes to your original model and am attaching the new model. I used v4.4 to solve the model, thats the only version I have access to. I attached the file by clearing all meshes and solutions so you will have to run the file before you can look at the solution. Hope this helps.
--Sri
If I understand your question correctly, you are worried that the solution get does not make sense. I have a few suggestions. First, first the inside and the annular pipes, which do not have porous media, you can use the same physics (turbulent flow). For the porous medium use Darcy's law. All your physics were correct, your boundary conditions needed some adjustment. For the interface between the membrane and the two flows, the better boundary condition to use is matching pressures. If you match pressures, mass continuity will match flows and you will get a realistic solution. I have made a few changes to your original model and am attaching the new model. I used v4.4 to solve the model, thats the only version I have access to. I attached the file by clearing all meshes and solutions so you will have to run the file before you can look at the solution. Hope this helps.
--Sri