Planar (2D) Poiseuille Flow

Asked by Kyle

Hello Everyone,

I was not able to locate any examples using planar poiseuille flow with FEniCS. Do any demos exist for this type of problem?

Thank you,

Kyle

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B. Emek Abali
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B. Emek Abali (bilenemek) said :
#1

Hi take a look at my WebSite, under Computational Reality tutorials number 06 is a viscous fluid flow in 2D with the Navier Stokes constitutive relations.

http://www.lkm.tu-berlin.de/menue/mitarbeiter_sprechstunden/b_emek_abali_msc/

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Kent-Andre Mardal (kent-and) said :
#2

Nice work!!!

Kent

On 18 April 2011 12:51, B. Emek Abali
<email address hidden>wrote:

> Question #152917 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/152917
>
> Status: Open => Answered
>
> B. Emek Abali proposed the following answer:
> Hi take a look at my WebSite, under Computational Reality tutorials
> number 06 is a viscous fluid flow in 2D with the Navier Stokes
> constitutive relations.
>
> http://www.lkm.tu-
> berlin.de/menue/mitarbeiter_sprechstunden/b_emek_abali_msc/
>
> --
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B. Emek Abali (bilenemek) said :
#3

you mean FEniCS :) lol

we started a new project based course doing these kind of works with small student groups, all with FEniCS...

Revision history for this message
Kyle (kylekyle) said :
#4

Thank you for the information! The tutorials are very helpful. I should join your course lol.

I still do have questions regarding my specific question.

I am considering 2D Poiseuille flow that is two parallel plates of length x=L positioned at y=+H/-H. A pressure gradient is applied that directs the flow and the top and bottom are considered to have no-slip conditions.

So from the Navier-Stokes equation the equation of linear momentum for 2d Poiseuille flow reads:

dp/dx - u(d^2v)/(dy^2) = 0

and

dp/dy = 0

Where:

p=pressure
u=viscosity
v=velocity
x=pipe length
y=pipe width

BCs are such that:

v = 0 at the top and bottom
v inlet = (1-y^2)
p outlet = 0

I guess I am stuck more at the variational formulation of the problem than anything else. I think with the variational formulation part I would be able to solve the problem using FEniCS. I have been reading about the variational formulation through tutorials but I don't understand it completely.

Grazie!

Kyle

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Best B. Emek Abali (bilenemek) said :
#5

this is how I also explained in the tutorial Kyle,

for solving pressure AND velocities you need also mass balance AND momentum balance

the pde you got is only the momentum balance (stationary) with a stress definition, only the half!

You may ask concrete questions but I believe that the tutorials are self contained (for engineers), try to start from 01 there you will find some more for the beginners.

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Kyle (kylekyle) said :
#6

Thank yuu again for your help Emek Abali,

I guess the difference is that my problem is steady-state and I would not like it to be time-dependant for now. Do you know what would change in this case?

Kyle

Revision history for this message
B. Emek Abali (bilenemek) said :
#7

You should drop the partial time derivative parts out of the equation. But remember that You might have numerical problems if the viscosity is not high enough.

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Anders Logg (logg) said :
#8

On Mon, Apr 18, 2011 at 11:26:25AM -0000, B. Emek Abali wrote:
> Question #152917 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/152917
>
> B. Emek Abali posted a new comment:
> you mean FEniCS :) lol
>
> we started a new project based course doing these kind of works with
> small student groups, all with FEniCS...

Very nice! When we get the new web page in place (working on it), we
should have a page with links to projects/courses that use FEniCS.

I've added a note about your page and will add it once the new pages
are in place. If anyone else knows about related projects/courses that
we should link to, let me know.

--
Anders

Revision history for this message
B. Emek Abali (bilenemek) said :
#9
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Kyle (kylekyle) said :
#10

Thanks B. Emek Abali, that solved my question.