[Nek5000-users] Variable density flows

Sat Oct 12 13:29:16 CDT 2013

Hello

What type of BC are available for temperature/passive scalar at the outlet
of a channel flow ? Can one use the outflow bc 'O' for these scalars ?

For scalars, when we specify insulated bc 'I' does this set
convective+diffusive flux to be zero ?

Thanks
praveen

On Sat, Oct 12, 2013 at 10:58 PM, Praveen Chandrashekar <
nek5000 at praveen.e4ward.com> wrote:

> Hi
> My problem is flow in a 2d channel. The initial condition is zero velocity
> in the channel and there is an inlet flow. I have a passive scalar which is
> flowing in through inlet. Initial temperature is zero everywhere. I am
> having trouble getting initial iterations to converge. I am trying stress
> formulation and passive scalars for first time and I do not see what is
> going wrong.
>
>
>              Solving for heat
>  Solving for fluid F F T
>   Temperature/Passive scalar solution
>    1.0000000000000001E-009  p22            1           2
>  New CG1-tolerance (RINIT*epsm) =    8.4585499354425527E-033   2.
>       5514287912844953E-033
>   1     1 Helmholtz TEMP    F:   8.4585E-20   1.0000E-09   2.8571E-04
> 0.0000E+00
>           1    Hmholtz TEMP:      0   8.4585E-20   8.4585E-20   1.0000E-09
>    1.0000000000000001E-009  p22            1           2
>  New CG1-tolerance (RINIT*epsm) =    5.8174583141330990E-032   1.
>       7860001538991468E-032
>   1     1 Helmholtz PS 1    F:   5.8175E-19   1.0000E-09   2.0000E-03
> 0.0000E+00
>           1    Hmholtz PS 1:      0   5.8175E-19   5.8175E-19   1.0000E-09
>           1   0.0000E+00  6.0799E-03 Heat done
>  New CG1(stress)-tolerance (RINIT*epsm) =    6.9206392325228944E-014   4.
>       2096427334076814E-033
>   0  1.0000E-09  6.9206E-14  1.0000E-09 tol,matmod
>            1 tx3:      1   0.3584E+00   0.1000E-08   0.3584E+00
>            1 tx3:      2   0.2546E+00   0.1000E-08   0.3584E+00
>            1 tx3:      3   0.1905E+00   0.1000E-08   0.3584E+00
> .
> .
> .
>            1 tx3:    198   0.1080E-02   0.1000E-08   0.3584E+00
>            1 tx3:    199   0.1067E-02   0.1000E-08   0.3584E+00
>            1 tx3:    200   0.1033E-02   0.1000E-08   0.3584E+00
>      1   201 Unconverged Helmholtz3/Fluid: rbnorm = 0.103306E-02
> 0.100000E-08
>     1 1.00000E-07 2.34297E-01 2.34297E-01 1.00000E+00       1 Divergence
>  New CG1(stress)-tolerance (RINIT*epsm) =    1.5438583947746548E-016   4.
>       2096427334076814E-033
>   0  1.0000E-09  1.5439E-16  1.0000E-09 tol,matmod
>            1 tx3:      1   0.8855E-02   0.1000E-08   0.8855E-02
>            1 tx3:      2   0.5463E-02   0.1000E-08   0.8855E-02
>            1 tx3:      3   0.5217E-02   0.1000E-08   0.8855E-02
>
> Thanks a lot
> praveen
>
>
> On Sat, Oct 12, 2013 at 10:04 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>>
>> Hi Praveen,
>>
>> That looks right... As always, it's best to run a test
>> to verify first.
>>
>> Paul
>>
>>
>> ----- Original Message -----
>> From: nek5000-users at lists.mcs.anl.gov
>> To: nek5000-users at lists.mcs.anl.gov
>> Sent: Saturday, October 12, 2013 11:17:06 AM
>> Subject: Re: [Nek5000-users] Variable density flows
>>
>>
>>
>> Thanks to Paul and Ammar. I will try the variable density approach.
>>
>>
>> I am first trying a case in which viscosity depends on temperature and a
>> passive scalar. My uservp looks like this. Can I use "temp" and "PS" to get
>> temperature and passive scalar as below ?
>>
>>
>>
>> subroutine uservp (ix,iy,iz,ieg)
>> include 'SIZE'
>> include 'TOTAL'
>> include 'NEKUSE'
>> common /mygeom/ xmin,xmax
>> common /myparam/ r_k,Rey_no,Pr_no,Sc_no,visc_rat
>>
>>
>> if(ifield.eq.1)then ! momentum equation
>> utrans= 1.0
>> udiff = exp(PS(1)*log(visc_rat) - temp)/Rey_no
>> else if(ifield.eq.2)then ! temperature eqn
>> utrans= 1.0
>> udiff = PS(1)*(r_k - 1.0) + 1.0
>> udiff = udiff/(Rey_no*Pr_no)
>> else if(ifield.eq.3)then ! passive scalar
>> utrans= 1.0
>> udiff = 1.0/(Rey_no*Sc_no)
>> else
>> print*,'Only 3 fields'
>> call exitt()
>> endif
>>
>>
>> return
>> end
>>
>>
>> Thanks
>> praveen
>> _______________________________________________
>> 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
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20131012/6d2e4dce/attachment.html>