[Nek5000-users] Pulsatile Flow in NEK5000

[nek5000-users at lists.mcs.anl.gov]

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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