[Nek5000-users] Location based viscosity

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

Thanks Paul and Aleks, that helps a lot!

I'm using Pn-Pn right now, but I think I'll switch to Pn-Pn-2 shortly.
 I understand the difference between the two formulations, but is
there a reason where one might use one formulation over the other?
(stability, speed, etc...)  (Sorry if this question is off-subject)

Josh


On Thu, Mar 24, 2011 at 10:06 AM,  <nek5000-users at lists.mcs.anl.gov> wrote:
> Hi Josh,
>
> make sure you accivating a call to uservp by either setting
>
>      ifuservp = .true.
>
> say in usrdat2 passed through 'TOTAL' or by p30>0 in .rea
>
> Best,
> Aleks
>
>
>
> On Thu, 24 Mar 2011, nek5000-users at lists.mcs.anl.gov wrote:
>
>>
>> Hi Josh,
>>
>> How about setting "udiff" in uservp?
>>
>> Note that if you have more than one field (e.g., temperature and velocity)
>> then you discriminate by ifield:
>>
>>     if (ifield.eq.1)  then  ! viscosity
>>
>>        udiff   = my viscosity
>>        utrans  = my rho
>>
>>     elseif (ifield.eq.2)  then  ! conductivity
>>
>>        udiff   = my conductivity
>>        utrans  = my rho C_p
>>
>>     endif
>>
>>
>> Note that technically, you should use the full stress tensor
>> when doing this, since the d/dxj mu du_j/dx_i
>> term no longer vanishes.
>>
>> Are you using PnPn, or PnPn-2 ?
>>
>>
>> Paul
>>
>>
>> On Thu, 24 Mar 2011, nek5000-users at lists.mcs.anl.gov wrote:
>>
>>> Hello Neks,
>>>
>>> This seems like it should be simple, but can somehow show me how I can
>>> vary viscosity based on a given x, y, z?
>>>
>>> I'm guessing I should be able to do this in uservp, looking at the
>>> var_visc example, but I don't immediately see a variable that I can
>>> edit in NEKUSE (like I could for ux, uy, etc....)
>>>
>>> Thanks,
>>>
>>> --
>>> Josh Camp
>>>
>>> "All that is necessary for the triumph of evil is that good men do
>>> nothing" -- Edmund Burke
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-- 
Josh Camp

"All that is necessary for the triumph of evil is that good men do
nothing" -- Edmund Burke