[Nek5000-users] Nek5000-users Digest, Vol 54, Issue 1

Tue Aug 6 17:34:44 CDT 2013

Hi Paul,

Thanks so much for the help and quick response. The code is running fine. I
do realize that this is not a Womersley inlet. In fact I have access to
patient specific Doppler measured velocity profiles (V of T in this case)
that I am implementing with the assumption of a fully developed flow. This
is justified to some extent since the vein in reality, before the spot that
we consider the inlet for our study, is long enough to develop a parabolic
profile in the tube.

Am still waiting for any ideas if the Sponge outlet condition can be used
with stress formulation for non-Newtonian flows.

Cheers,
Javid

On Tue, Aug 6, 2013 at 12:00 PM, <nek5000-users-request at lists.mcs.anl.gov>wrote:

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> Today's Topics:
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>    1. Pulsatile Flow in NEK5000 (nek5000-users at lists.mcs.anl.gov)
>    2. Re: Pulsatile Flow in NEK5000 (nek5000-users at lists.mcs.anl.gov)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 5 Aug 2013 16:19:37 -0500
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov, Cassel Kevin <cassel at iit.edu>
> Subject: [Nek5000-users] Pulsatile Flow in NEK5000
> Message-ID:
>         <mailman.12039.1375737604.15097.nek5000-users at lists.mcs.anl.gov>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi There NEKs,
>
> I am currently trying to run a case with pulsatile inlet condition. The
> context is pulsatile stenotic flows. I have two Question regrading the set
> up:
>
> 1st Question) How do I access the "Time" variable in NEK5000? I need to
> define a time dependent inlet velocity condition in the user file. V as a
> function of Y and T. I already have the function which is a patient
> specific velocity inlet profile. Please note that this should be a
> pulsatile flow. This, I assume, is different than a periodic flow. I'll be
> investigation the effect of pulsatility on some 2D geometries.
> It would be wonderful to know how to implement time dependent inlet
> velocity condition in user file. Previously I have only used steady
>  and parabolic inlet velocity.
>
> 2nd Question) I will be using a simple Dirichlet BC on pressure for the
> outlet. I have also used the Nozzle outlet condition but, as it turns out,
> I cannot use the Nozzle condition with stress formulation. I wanted to know
> if the Sponge condition for outlet is proper and if it can be coupled with
> stress formulation? I am considering a non-Newtonian fluid with variable
> viscosity for my simulation.
>
> Any assistance is greatly appreciated.
>
> Best of luck to everyone,
> Javid
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> ------------------------------
>
> Message: 2
> Date: Mon, 5 Aug 2013 17:24:32 -0500 (CDT)
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Pulsatile Flow in NEK5000
> Message-ID:
>         <mailman.12049.1375741473.15097.nek5000-users at lists.mcs.anl.gov>
> Content-Type: text/plain; charset=utf-8
>
>
> Hi Javid,
>
> You simply need to use the "time" variable, e.g.,
>
>
>       ux=1-y*y
>
> gives the steady state solution, whereas
>
>       eps = 0.1
>       period = 5.0
>       arg = 2*pi*time/period
>       ux = (1-y*y)*(1+eps*sin(arg))
>
> would give a sinusoidal fluctuation.  (Note that this is
> _not_ the Womersely solution that is the exact inlet
> condition for fully developed pulsatile flow...)
>
> Regarding outflow, I don't know why the standard nozzle
> approach would not work with the stress formulation.
> Am on travel at the moment and don't have time to dig
> into this, but perhaps someone else can assist.
>
> Best, Paul
>
>
>
> ----- Original Message -----
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov, "Cassel Kevin" <cassel at iit.edu>
> Sent: Monday, August 5, 2013 4:19:37 PM
> Subject: [Nek5000-users] Pulsatile Flow in NEK5000
>
>
>
> Hi There NEKs,
>
>
> I am currently trying to run a case with pulsatile inlet condition. The
> context is pulsatile stenotic flows. I have two Question regrading the set
> up:
>
>
> 1st Question) How do I access the "Time" variable in NEK5000? I need to
> define a time dependent inlet velocity condition in the user file. V as a
> function of Y and T. I already have the function which is a patient
> specific velocity inlet profile. Please note that this should be a
> pulsatile flow. This, I assume, is different than a periodic flow. I'll be
> investigation the effect of pulsatility on some 2D geometries.
> It would be wonderful to know how to implement time dependent inlet
> velocity condition in user file. Previously I have only used steady and
> parabolic inlet velocity.
>
>
> 2nd Question) I will be using a simple Dirichlet BC on pressure for the
> outlet. I have also used the Nozzle outlet condition but, as it turns out,
> I cannot use the Nozzle condition with stress formulation. I wanted to know
> if the Sponge condition for outlet is proper and if it can be coupled with
> stress formulation? I am considering a non-Newtonian fluid with variable
> viscosity for my simulation.
>
>
> Any assistance is greatly appreciated.
>
>
> Best of luck to everyone,
> Javid
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> End of Nek5000-users Digest, Vol 54, Issue 1
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