[Nek5000-users] Variable density flows
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
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
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