[Nek5000-users] Nek5000 and Non-Newtonian Fluids

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

Hi Mike,

Just added "var_vis" to /examples --- it's a test
case that I've tested in the past (no exact solution).

So far, all exact solns I've found don't properly exercise
the full stress tensor, whereas this particular example
does - but I don't know the exact solution.  In this case,
I rely on the fact that the code is correct and convergent
and thus trust that we are getting the right answer.  If
you happen to think of a case that is a better test (I'm
certain they exist), please let me know.

I believe that if you cd to /examples and say "svn update"
that you will find this case deposited into your repo.

Let me know if otherwise.

Cheers,

Paul


On Tue, 18 Jan 2011, nek5000-users at lists.mcs.anl.gov wrote:

> Paul,
>
> That's got what I need, thanks.
>
> Also, are there any examples in the distribution that use the stress formulation and variable viscosity?
>
> Thanks.
> --Mike
>
> On Jan 18, 2011, at 6:22 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>>
>> Hi Mike,
>>
>> Probably the best point to start is in the lambda2 routine,
>> to be found in postpro.f, which reads in part as:
>>
>>
>>       do ie=1,nelv
>>          ! Compute velocity gradient tensor
>>          call comp_gije(gije,vx(1,1,1,ie),vy(1,1,1,ie),vz(1,1,1,ie),ie)
>>
>>          do l=1,nxyz
>>             ! decompose into symm. and antisymm. part
>>             do j=1,ndim
>>             do i=1,ndim
>>                ss(i,j) = 0.5*(gije(l,i,j)+gije(l,j,i))
>>                oo(i,j) = 0.5*(gije(l,i,j)-gije(l,j,i))
>>             enddo
>>             enddo
>>
>> etc.
>>
>> I think from their you can see how to compute what you need.
>> (Let me know if you have questions...)
>>
>> If you get such a routine (e.g., "compute_q") and are happy
>> with it after a few trials, I'd be happy to insert it into the repo.
>>
>> Cheers,
>>
>> Paul
>>
>>
>>
>> On Mon, 17 Jan 2011, nek5000-users at lists.mcs.anl.gov wrote:
>>
>>> Paul,
>>>
>>> I switched this to the nek5000-users channel  in case we discuss some thing relevant to others.
>>>
>>> For the Bingham model, it seems that all I need is to calculate the second invariant of the strain rate tensor, which is then used to calculate the time-varying apparent viscosity.   I suspect the routine building-blocks for generating this tensor are already in the nek distribution.  If so, could you point me in that direction?
>>>
>>> Once those routines are in order, all the calculation will be directed out of uservp, correct?
>>>
>>> Thanks.
>>> --Mike
>>>
>>>
>>> On Jan 14, 2011, at 7:27 AM, Paul Fischer wrote:
>>>
>>>> Hi Mike,
>>>>
>>>> [...]
>>>> The "peris" case uses the stress formulation, as do the "fs"
>>>> cases.  These have the correct SiZE files (resp. for 3D and 2D)
>>>> and flags in the .rea file, save that you would set "IFMVBD"
>>>> to false, since you don't want moving boundaries.
>>>>
>>>> [...]
>>>> The code was used
>>>> for a lot of non-Newtonian stuff by Lee Ho and Einar, however,
>>>> so it has been exercised significantly in the past.
>>>> [...]
>>>
>>> _______________________________________________
>>> Nek5000-users mailing list
>>> Nek5000-users at lists.mcs.anl.gov
>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>
> _______________________________________________
> Nek5000-users mailing list
> Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>